Ceramic-bearing bicycle drive shaft (2018)(bikeradar.com)
bikeradar.com
Ceramic-bearing bicycle drive shaft (2018)
https://www.bikeradar.com/news/faster-than-any-chain-ceramicspeed-driven/?image=3&type=gallery&gallery=1&embedded_slideshow=1
131 comments
Agreed, rolling resistance at 30mph (about the fastest you'll ever ride a bike, even down a steep hill) is about 50w of energy, whereas wind resistance at that speed is close to 1000w of energy.
Compare to 10mph (average speed for most casuals) where your total wind + drivetrain is about 50w of energy. Wind resistance goes up by the cube, drivetrain is mostly linear.
Compare to 10mph (average speed for most casuals) where your total wind + drivetrain is about 50w of energy. Wind resistance goes up by the cube, drivetrain is mostly linear.
> Agreed, rolling resistance at 30mph (about the fastest you'll ever ride a bike, even down a steep hill)
What do you consider a steep hill? There are hills here that I can routinely get up to 35 mph with a little effort. Many cyclists have gone downhill at speeds exceeding 50 mph [1].
[1] https://www.youtube.com/watch?v=sc2nqMXlZWg
What do you consider a steep hill? There are hills here that I can routinely get up to 35 mph with a little effort. Many cyclists have gone downhill at speeds exceeding 50 mph [1].
[1] https://www.youtube.com/watch?v=sc2nqMXlZWg
Most people who aren't hardcore cyclists with really nice bikes are going to chicken out around 30 MPH.
Or they should. 30 MPH is fast on a bike. If anything goes wrong, it's going to hurt.
Or they should. 30 MPH is fast on a bike. If anything goes wrong, it's going to hurt.
Then i've been lucky, since i did that and much more in the past. Nowadays i'm doing 22 to 23 up to 28 peak on flat ground with no headwind. On a decades old 3-speed, with coaster/back pedal brake, mud guards and basket on the (rear)carrier. (27x1 1/4 pumped to 7.5 to 8 bars)
The only thing of going wrong i can think of is insects in the eye, and generally unpleasant airstream in the eyes. Use sports glasses. Problem solved. Anything else is situtational awareness, maybe a helmet, and good maintenance.
The only thing of going wrong i can think of is insects in the eye, and generally unpleasant airstream in the eyes. Use sports glasses. Problem solved. Anything else is situtational awareness, maybe a helmet, and good maintenance.
We used to routinely do 55mph going down mountain passes in Washington State on $30 goodwill bicycles but I think that is well outside the scope of "about the fastest".
Conceptually you seem correct but your numbers are a bit off.
Down a steep hill on my road cycle I can easily get to 45-50mph.
Rolling resistance doesn't change that much with speed[1].
Rolling resistance energy balance at 18mph is on the order of 10-15W[2]
Drag increases with the square of velocity (D=0.5 * <drag coefficient> * <representative cross sectional area> * <air density> * <velocity>^2).
The drag energy balance (plus some rolling resistance) at 10, 20, and 30mph is on the order of 10, 100, and 300W, respectively[3].
[1]https://www.schwalbe.com/en/rollwiderstand.html (see section "what exactly is rolling resistance")
[2]https://www.bicyclerollingresistance.com/road-bike-reviews
[3]https://www.exploratorium.edu/cycling/aerodynamics1.html (see the calculator)
Down a steep hill on my road cycle I can easily get to 45-50mph.
Rolling resistance doesn't change that much with speed[1].
Rolling resistance energy balance at 18mph is on the order of 10-15W[2]
Drag increases with the square of velocity (D=0.5 * <drag coefficient> * <representative cross sectional area> * <air density> * <velocity>^2).
The drag energy balance (plus some rolling resistance) at 10, 20, and 30mph is on the order of 10, 100, and 300W, respectively[3].
[1]https://www.schwalbe.com/en/rollwiderstand.html (see section "what exactly is rolling resistance")
[2]https://www.bicyclerollingresistance.com/road-bike-reviews
[3]https://www.exploratorium.edu/cycling/aerodynamics1.html (see the calculator)
These #s are way off.
30mph does not require anywhere near 1000w, it's more like 350-400w on flat ground depending on the riders position and size. I'm a former amateur racer. I've done 30mph steady state for a mile on flat ground without a draft before. That's a 2 minute mile and there is no way on earth I could ever do 2 minutes @ 1000w. 1000w is more like a 5s sprint for an amateur, you would put that power out in a burst to accelerate and probably end up doing about 34-35mph on flat assuming no draft. Pros are probably more like 1500w. 30mph is nothing. I probably exceed 30mph every time I get on my bicycle if I'm riding for exercise as opposed to commuting. Almost no race goes on where speeds don't hit 40mph, and 50-60mph is not rare.
Rolling resistance is not drivetrain resistance. Most of rolling resistance is tire resistance. It doesn't scale up at the same rate as aerodynamic drag.
Chain resistance is much smaller than tire resistance. It does go up with power but not really with speed directly because you shift.
30mph does not require anywhere near 1000w, it's more like 350-400w on flat ground depending on the riders position and size. I'm a former amateur racer. I've done 30mph steady state for a mile on flat ground without a draft before. That's a 2 minute mile and there is no way on earth I could ever do 2 minutes @ 1000w. 1000w is more like a 5s sprint for an amateur, you would put that power out in a burst to accelerate and probably end up doing about 34-35mph on flat assuming no draft. Pros are probably more like 1500w. 30mph is nothing. I probably exceed 30mph every time I get on my bicycle if I'm riding for exercise as opposed to commuting. Almost no race goes on where speeds don't hit 40mph, and 50-60mph is not rare.
Rolling resistance is not drivetrain resistance. Most of rolling resistance is tire resistance. It doesn't scale up at the same rate as aerodynamic drag.
Chain resistance is much smaller than tire resistance. It does go up with power but not really with speed directly because you shift.
400W is too low :) but 750W Bafang motor with non speed locked controller will get you to 50km/s without pedaling (not that I would recommend going that fast).
50 km/hr
50 km/s is over mach 145 :)
50 km/s is over mach 145 :)
Don't use the rated wattage of your motor for this kind of comparison. Some electric motors can run briefly at 10x or more their rated current, and sustained if they have very good cooling.
Likewise, poor cooling can lead to a 10x decrease in motor performance.
Cooling is usually the biggest limiter of power, but max rpm (before the thing blows apart) combined with iron saturation (effectively meaning the magnetic fields inside can't get any stronger, even with more current) can also be a limit.
Likewise, poor cooling can lead to a 10x decrease in motor performance.
Cooling is usually the biggest limiter of power, but max rpm (before the thing blows apart) combined with iron saturation (effectively meaning the magnetic fields inside can't get any stronger, even with more current) can also be a limit.
Not unrelated to the patent https://patents.google.com/patent/EP0105949A3/ko
2019-08-16
Application status is Expired
What a funny coincidence
(Not implying anything about the company in article, the article is from july 2018)
What a funny coincidence
(Not implying anything about the company in article, the article is from july 2018)
That can be very easily changed. Infact i'd say most writers do change it either to appear older(to add credibility) or newer(to stay relevant.)
I, too, thought I had magic patent expiring powers, but that line shows today’s date and the status as of today.
If you check tomorrow, it’ll say “2019-08-17 Application status is Expired” instead.
If you check tomorrow, it’ll say “2019-08-17 Application status is Expired” instead.
Of course, this makes so much sense, and it changed indeed, hahaha
The sideways forces on those sprockets are going to lead to very rapid failure...
Absolutely, putting full-load on those sprockets is not going to happen, either the sprockets will bend or the bearings will pop-out. Interesting design tho
Previous HN discussion: https://news.ycombinator.com/item?id=17494226
Can't imagine this catching on. Ordinary chains are already really efficient, and the efficiency of this will only last until dirt gets into all those tiny little open bearings. (Sealed bearings would eat into the efficiency gains.)
Can't imagine this catching on. Ordinary chains are already really efficient, and the efficiency of this will only last until dirt gets into all those tiny little open bearings. (Sealed bearings would eat into the efficiency gains.)
Something which would be cool would be a electric hybrid drive. Electric generator + electric motor.
You can already buy electric bicycles. But regenerative braking on such a light vehicle doesn't gain enough to be worth the extra weight.
[deleted]
I know someone who uses an electric cargo bike. It has regenerative braking, and perhaps the extra mass of carrying loads is what makes it practical.
I believe it uses the Bionx system, which uses a direct hub drive. The company is lo longer in business, IIRC.
I believe it uses the Bionx system, which uses a direct hub drive. The company is lo longer in business, IIRC.
I don't know if it's feasible, but I was thinking motor <-- cabling --> crankshaft with integrated generator
Not necessarily any battery, but the electric cabling replacing chains.
Not necessarily any battery, but the electric cabling replacing chains.
You can buy e-bikes with regenerative braking. They don't advertise it much but as far as I know, all Stromer's [0] e-bikes have it.
[0]: https://www.stromerbike.com/en_INT.html
[0]: https://www.stromerbike.com/en_INT.html
Put the shaft in a tube that is removable and cleanable.
Jeasus guys - engineering can solve ALL of these issues.
Jeasus guys - engineering can solve ALL of these issues.
What are the efficiency numbers when using normal, grease and shield laden bearings? This might have a place in cycle sprints or other short distance disciplines where you have a lot of time for prep, but the benefits are quite moot if you have to swap or service bearings every hundred km.
92-96%
are those actual numbers or are you just showing it is high?
I'd have guessed it's more like 99%. isn't anything that isn't heat or noise = perfect efficiency? a normal bike chain doesn't get hot or make much noise at all, does it? seems to me just about 100% efficient. maybe transfers a bit of vibration to the rest of the frame? but not 8%-4% of its transferred force....
I'd have guessed it's more like 99%. isn't anything that isn't heat or noise = perfect efficiency? a normal bike chain doesn't get hot or make much noise at all, does it? seems to me just about 100% efficient. maybe transfers a bit of vibration to the rest of the frame? but not 8%-4% of its transferred force....
I think the GP is right, I did a quick Google and found sites saying 93-97.5% and it depends on power output. I would expect a dirty chain to be worse.
thanks, that is certainly interesting.
An athlete will only generate ~200w which isn't a lot for a fairly large metal part with plenty of air cooling. Even if it was only 50% efficient you might struggle to notice an appreciable change in temperature.
Motorcycles can have 150hp engines (~100kw) and even then the chain doesn't get particularly hot.
Motorcycles can have 150hp engines (~100kw) and even then the chain doesn't get particularly hot.
I might be a bike fanatic, but I'm no professional athlete and I can sustain more than 200W for hours, so my guess is the pro's are quite a bit higher again. (Your point still stands, though)
You are right, serves me right for going by memory. 200w is closer to an average cyclist, a pro is closer to 500w. Still, the orders of magnitude don't change.
During a sprint in 2018, Andre Greipel averaged 1,600W, and hit 1,900W peak. Those are the kind of numbers engineers have to take into consideration when designing for maximum torque, although obviously they are not sustained for hours.
Wait, you're saying 1 human = 2.5 horses?
Fun fact. Peak horse power for a horse is 14.9hp :)
This paper gives a very detailed analysis of chain drive efficiency:
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
Wow, thanks. I only had a quick look but Figure 2 seems to show 91.5%-95% efficiency depending on configuration. Very detailed study and it sounds like it would answer all my questions if I spent an hour reading it.
I’ve had two shaft drive motorbikes now and appreciated the low maintenance and general cleanliness but they are heavier than chain drives. On a bicycle, this looks great, although it would be better off enclosed for protection - but fewer showhorse points.
The detail about changing gears is glossed over, there is that big stack of what look like sprockets so it is assumed that changing gear is possible, but, get to the bottom of the article, and it isn't.
This is doing well as a fake-halo product for Ceramic Speed and their existing products, it is a crowded marketplace and not many people care about bike bearings, this product makes people aware that there is room for efficiency gains.
This is doing well as a fake-halo product for Ceramic Speed and their existing products, it is a crowded marketplace and not many people care about bike bearings, this product makes people aware that there is room for efficiency gains.
Agreed, shifting is the big problem. This would basically need a clutch to stay efficient.
> The detail about changing gears is glossed over, there is that big stack of what look like sprockets so it is assumed that changing gear is possible, but, get to the bottom of the article, and it isn't.
Actually, it's not - take a look at the renderings again.
If you notice (and the article details) the rear "cassette" is actually a flat disk with concentric "gearing" which the roller bearing "gear" on the shaft interfaces with.
Switching gears would be accomplished (in theory) by moving the roller bearing "gear" in and out along the radius of the rear disc "gear".
It reminds me in a way of old wood "peg" and "lantern" gearing seen in wind/water mills and similar old power transmission systems, except in this case the "peg" gear is a formed or cast disc, and the "lantern" (which you couldn't shift due to the plates at the ends) is a "ring" of bearings, the bearings forming the "teeth" of the gear (which isn't that strange, if you understand how a simple gear is basically formed out of partial circles along the edge of a larger circle, all "joined up").
They do mention though, at the end of the article, that they can't shift gears easily and something about an internal wireless servo (which I think is kinda daft). I would instead use a splined shaft, and just change the "length" of the shaft to move the end-gear in/out of the wheel gear, and actuate it with a normal lever and bowden-cable type arrangement, though that might interfere with their efforts/want for more efficiency...
Actually, it's not - take a look at the renderings again.
If you notice (and the article details) the rear "cassette" is actually a flat disk with concentric "gearing" which the roller bearing "gear" on the shaft interfaces with.
Switching gears would be accomplished (in theory) by moving the roller bearing "gear" in and out along the radius of the rear disc "gear".
It reminds me in a way of old wood "peg" and "lantern" gearing seen in wind/water mills and similar old power transmission systems, except in this case the "peg" gear is a formed or cast disc, and the "lantern" (which you couldn't shift due to the plates at the ends) is a "ring" of bearings, the bearings forming the "teeth" of the gear (which isn't that strange, if you understand how a simple gear is basically formed out of partial circles along the edge of a larger circle, all "joined up").
They do mention though, at the end of the article, that they can't shift gears easily and something about an internal wireless servo (which I think is kinda daft). I would instead use a splined shaft, and just change the "length" of the shaft to move the end-gear in/out of the wheel gear, and actuate it with a normal lever and bowden-cable type arrangement, though that might interfere with their efforts/want for more efficiency...
The thing is that this gadget has been doing the rounds of trade shows for more than a year with this unfinished detail of having it actually change gear.
There is this difference between theory and practice. So even if there was a solution - yours is elegant b.t.w. - then it would take a whole lot of testing and fine tuning to get right.
I am actually quite astonished at how bicycle parts evolve, the derailleur took the best part of a century to get indexed gears and those took decades to go from clunky to smooth. What took so long to get right? Scores of refinements were needed, e.g. to the sprocket teeth profiles, to being able to manufacture a decent chain to basics of friction in cables. Then there is the challenge of mass manufacturing these things so they are durable and precise.
I am not dismissing the ceramic speed shaft innovation - it gets people thinking - but I doubt my bike will be losing its chain any time soon!
There is this difference between theory and practice. So even if there was a solution - yours is elegant b.t.w. - then it would take a whole lot of testing and fine tuning to get right.
I am actually quite astonished at how bicycle parts evolve, the derailleur took the best part of a century to get indexed gears and those took decades to go from clunky to smooth. What took so long to get right? Scores of refinements were needed, e.g. to the sprocket teeth profiles, to being able to manufacture a decent chain to basics of friction in cables. Then there is the challenge of mass manufacturing these things so they are durable and precise.
I am not dismissing the ceramic speed shaft innovation - it gets people thinking - but I doubt my bike will be losing its chain any time soon!
I think the biggest innovation of this kind that I've seen in use (anecdata, of course) is the number of commuter bikes fitted with belt drivetrains (Gates Carbon Drive) paired with internally geared hubs. The reduction in maintenance effort is purported to be significant and it's not only limited to high-end bikes (plus it can be retrofitted although non-trivially for the majority of frames). When the cog wear becomes too bad on my single-speed I'll look into fitting a belt drive, if possible.
> commuter bikes fitted with belt drivetrains (Gates Carbon Drive) paired with internally geared hubs. The reduction in maintenance effort is purported to be significant
My understanding is that the tradeoffs are:
1. Weight
2. Cost
3. Lack of user serviceability.
It definitely seems like a good tradeoff in some circumstances - particularly in rainy environments.
My understanding is that the tradeoffs are:
1. Weight
2. Cost
3. Lack of user serviceability.
It definitely seems like a good tradeoff in some circumstances - particularly in rainy environments.
Or snowy with salt in the winter. For winter cycling the weight isn't really an issue for me, the bike is already sluggish with big studded tires and accessories and clothing etc. Maybe I will try it, the serviceability cannot be worse than the stuff I have to do now to maintain it..
> the serviceability cannot be worse than the stuff I have to do now to maintain it..
My understanding is that you can't maintain the hub shifter at all. It's sealed so it's generally pretty low maintenance, but if/when it eventually breaks you have to send it to the factory for repair.
My understanding is that you can't maintain the hub shifter at all. It's sealed so it's generally pretty low maintenance, but if/when it eventually breaks you have to send it to the factory for repair.
In my many years of having bikes with internal gear hubs, some new and some decades old, I've never had a single with them.
The internal gear hubs have been perfected before derailers even became a thing; it's a very mature tech.
You can[1] do some maintenance on them. I don't have any experience with that, as all my internally-hubbed bikes were stolen long before such a point :-) :-(
[1]https://www.sheldonbrown.com/internal-gears.html
The internal gear hubs have been perfected before derailers even became a thing; it's a very mature tech.
You can[1] do some maintenance on them. I don't have any experience with that, as all my internally-hubbed bikes were stolen long before such a point :-) :-(
[1]https://www.sheldonbrown.com/internal-gears.html
It's a good tradeoff in commuter purposes. It's not a good tradeoff for racing, which is where most tech is developed.
One big tradeoff you missed is efficiency. The belt drive is efficient, but internally geared hubs are currently less efficient than traditional derailleur setups. Losing watts to drivetrain loss is a major reason that internal hubs are not as popular with human powered bikes. The durability and maintenance need to be WAY better to get someone to switch over.
One big tradeoff you missed is efficiency. The belt drive is efficient, but internally geared hubs are currently less efficient than traditional derailleur setups. Losing watts to drivetrain loss is a major reason that internal hubs are not as popular with human powered bikes. The durability and maintenance need to be WAY better to get someone to switch over.
I'm interested in a belt drive, too, but mainly because I hate getting a greasy chain stamp on my leg. :P Belt drives don't need lube, so they stay pretty clean.
I'm surprised there are retrofit kits. With a belt drive, usually one of the chain stays has a gap in it so you can get the belt on and off (you accomplish the same with a chain by taking a link out to install/remove the chain, but this is not an option with a belt).
I'm surprised there are retrofit kits. With a belt drive, usually one of the chain stays has a gap in it so you can get the belt on and off (you accomplish the same with a chain by taking a link out to install/remove the chain, but this is not an option with a belt).
It's probably cheaper to put some plastic around your chain.
For a clean chain you can switch from a conventional lube to wax based lube. It’s a relatively involved process (You need to degrease your chain before application) but it keeps the chain relatively dry and clean. (Plus it’s slightly better performing than other lubes).
Scientific measurements or it didn’t happen. I think wax underperforms lube, prove me wrong.
https://www.ceramicspeed.com/media/3505/velonews-friction-fa...
See page 63 for efficiency and 64 for longevity.
The graph on page 64 is confusingly labeled, but the numbers indicate "watts expended before wet dirty run" - "watts expended after".
See page 63 for efficiency and 64 for longevity.
The graph on page 64 is confusingly labeled, but the numbers indicate "watts expended before wet dirty run" - "watts expended after".
Bit niche but there is one company making split belt: https://www.veercycle.com/
But it's 3-5x the price of chain equivalent setup.
But it's 3-5x the price of chain equivalent setup.
Why not just use a normal belt and some way of tensioning it like every other belt drive in the world uses? Seems like the fancy belt (and more importantly, the fancy pulleys that go with it) drives up cost substantially.
Look up-thread. You have to thread the belt through the frame. You either need a special frame with a gap in it, or a belt that can be split.
I read that part. That doesn't explain why they chose that oddball cogged belt instead of a commonly available belt profile (cogged or otherwise) for which pulleys are available off the shelf (or cheaply built to order) and belts are dirt cheap.
> (plus it can be retrofitted although non-trivially for the majority of frames)
Not at all: the chain goes through a closed triangle in the frame by connecting two loose ends. The belt comes as a closed loop and needs a frame that can be opened. Additionally, frames build for chain gearing (instead of internal gears or single-speed/fixed) lack tension adjustment by either a horizontally adjustable dropout or a bottom bracket excenter mechanism.
Not at all: the chain goes through a closed triangle in the frame by connecting two loose ends. The belt comes as a closed loop and needs a frame that can be opened. Additionally, frames build for chain gearing (instead of internal gears or single-speed/fixed) lack tension adjustment by either a horizontally adjustable dropout or a bottom bracket excenter mechanism.
>Additionally, frames build for chain gearing (instead of internal gears or single-speed/fixed) lack tension adjustment by either a horizontally adjustable dropout or a bottom bracket excenter mechanism.
Sliding dropouts are undoubtedly preferable, but any modern frame with a BB30 or PF30 bottom bracket can be trivially converted to an eccentric bottom bracket.
Sliding dropouts are undoubtedly preferable, but any modern frame with a BB30 or PF30 bottom bracket can be trivially converted to an eccentric bottom bracket.
I have been using a bike with belt drive for about 2 years and while the lack of chain reduces some maintenance doing other maintenance like switching tires gets more complicated.
And of course the loss of efficiency due to belt drive is also pretty bad.
I am convinced that this will be my last belt drive bike.
And of course the loss of efficiency due to belt drive is also pretty bad.
I am convinced that this will be my last belt drive bike.
Another disadvantage is repairability. If your chain snaps you can fix it with a quick link or a pin and a little multitool with chain tool functionality. If your belt snaps you‘re screwed, unless you carry a spare belt everywhere.
Has a belt ever snapped? Serious question. I've never heard of it happening, and the belt drive bike I've been riding for 4 years isn't even wearing, let alone close to snapping.
If you google gates belt drive snapped you‘ll find plenty of anecdata of belts lasting only a couple thousand kilometers (and others who ride them for tens of thousands of kilometers with no issues).
Here‘s a (German) Video from a guy with a severely damaged (but still rideable) belt after 4500 km:
https://m.youtube.com/watch?v=n16gN7RDWEY
In the comments you‘ll find people whose belts snapped at 1050 km, at 1000 km and one at less than 2000 km.
I don‘t know how likely this is, it might be quite rare. But since it‘s non-repairable it‘d make me uneasy on longer bike rides.
Here‘s a (German) Video from a guy with a severely damaged (but still rideable) belt after 4500 km:
https://m.youtube.com/watch?v=n16gN7RDWEY
In the comments you‘ll find people whose belts snapped at 1050 km, at 1000 km and one at less than 2000 km.
I don‘t know how likely this is, it might be quite rare. But since it‘s non-repairable it‘d make me uneasy on longer bike rides.
I've had a Spot ACME with belt for about 6 years. I've used in on my daily lunch ride 4+ days a week. I was worried about all that stuff, I love the bike and was worried about nothing.
Belt damage? They put these belts on motorcycles, it's possible to damage them but they are insanely durable, probably stronger than your typical chain. Somewhere I picked up a staple on mine, I'm going to get it replaced but I've done several hundred miles on it with no issues.
The IGHs are a different matter, they're pretty sensitive and if you get them off a little bit they work but your shifting will be hosed up. Bike shop fixed it all though. My advice? Don't mess with it, get it set up, make sure the little connector on the cable is tightly attached and you probably won't have issues, I had some slip on mine.
I've been running Conti touring tires with some mixed tread and pre-slimed tubes, I've not had flats but I've worn out 3 or 4 sets of tires. It's not a big deal to change it though. It's a commuter bike so it has bolts rather than quick release skewers, I'd use slime and maybe even kevlar liners if you get a lot of flats and just make tire changes a wear issue. It's a heavy bike, it's not a carbon roady by any stretch but it has been as close to zero maintenance as any bike I've had. It's actually required more maintenance on the disc brakes than the drive train, they were getting a little squishy but just rebleed them and they're good again. The only "issue" I've had was when I got a lot of dust on the belt, it was kind of squeaky for a while.
This carbon/ceramic drive shaft is kind of interesting. I always thought that the chain to pully and gear touch point was where the friction loss was, not interlink on the chain itself. For years and years, they've offered bigger pullies for reduced friction. This drive shaft will still have a similar touch point; also seeing as how both pieces rotate, it looks like there could be side to side friction as the cog on the shaft touches the gear on the wheel and they both rotate unless the cog and gear have some very special shaping that I'm not seeing. As the cog rotates, when it first can engage the gear, just the tip will be touching the gear but as it continues it will push more of the tooth on the cog in to the gear, am I wrong on this?
Belt damage? They put these belts on motorcycles, it's possible to damage them but they are insanely durable, probably stronger than your typical chain. Somewhere I picked up a staple on mine, I'm going to get it replaced but I've done several hundred miles on it with no issues.
The IGHs are a different matter, they're pretty sensitive and if you get them off a little bit they work but your shifting will be hosed up. Bike shop fixed it all though. My advice? Don't mess with it, get it set up, make sure the little connector on the cable is tightly attached and you probably won't have issues, I had some slip on mine.
I've been running Conti touring tires with some mixed tread and pre-slimed tubes, I've not had flats but I've worn out 3 or 4 sets of tires. It's not a big deal to change it though. It's a commuter bike so it has bolts rather than quick release skewers, I'd use slime and maybe even kevlar liners if you get a lot of flats and just make tire changes a wear issue. It's a heavy bike, it's not a carbon roady by any stretch but it has been as close to zero maintenance as any bike I've had. It's actually required more maintenance on the disc brakes than the drive train, they were getting a little squishy but just rebleed them and they're good again. The only "issue" I've had was when I got a lot of dust on the belt, it was kind of squeaky for a while.
This carbon/ceramic drive shaft is kind of interesting. I always thought that the chain to pully and gear touch point was where the friction loss was, not interlink on the chain itself. For years and years, they've offered bigger pullies for reduced friction. This drive shaft will still have a similar touch point; also seeing as how both pieces rotate, it looks like there could be side to side friction as the cog on the shaft touches the gear on the wheel and they both rotate unless the cog and gear have some very special shaping that I'm not seeing. As the cog rotates, when it first can engage the gear, just the tip will be touching the gear but as it continues it will push more of the tooth on the cog in to the gear, am I wrong on this?
Heh, look elsewhere in this thread and I ALMOST bought an Acme but bought a Ghost instead, and had issues with the Continental belt drive (even before it snapped, it squeaked every time it got remotely dirty).
I don't know about the Conti belt but the Gates has been rock solid since they introduced the center track guide. The first wave did have some problems unless the pullies had guides, they could slide off.
For what it is, I love it, it's not a racing bike though. I'm curious about the mtb uses with a Rohloff hub, it's a fair amount of weight.
For what it is, I love it, it's not a racing bike though. I'm curious about the mtb uses with a Rohloff hub, it's a fair amount of weight.
That is something which is really puzzling to me. Why doesn't anyone protect the belt with something like this:
[1] https://www.hebie.de/en/protection/chainguard/chainglider/35... ?
Are bicyles a fashion statement, or what?
"Seht her wie geil mein Riemen ist!"
[1] https://www.hebie.de/en/protection/chainguard/chainglider/35... ?
Are bicyles a fashion statement, or what?
"Seht her wie geil mein Riemen ist!"
Same for me. My Focus Planet is a 2015 model and I ride nearly every day; the blue coloring on the tooth side (presumably a wear indicator?) is barely worn through at any point.
Mine also has the Alfine 8 speed hub, which is kind of suck, but I make it work. I recently had it re-lubed (dunked) at my LBS, which seemed to help. I just wish there were some nice IGH in between the Alfine 8/11 and a Rohloff. I'd gladly pay for something better than the Shimano.
For commuters, I cannot fathom why people would deal with a chain when belts are a thing. Plus, good chains aren't cheap (I like Wippermann) and when you rack up miles you need to replace them enough that your wallet notices.
Tires: +1 for Schwalbe Marathons. Four years and no flats. NB: if you are worried about weight, upgrade to the Marathon Supremes with the aramid (foldable) bead. ~$75USD/each but totally worth it.
Oh yeah: a dynamo hub is a life-changer. My Focus came with a SP PD8 and lights, stock. Never having to strap on a light, or remember to charge it is a revelation.
Ride safe!
Mine also has the Alfine 8 speed hub, which is kind of suck, but I make it work. I recently had it re-lubed (dunked) at my LBS, which seemed to help. I just wish there were some nice IGH in between the Alfine 8/11 and a Rohloff. I'd gladly pay for something better than the Shimano.
For commuters, I cannot fathom why people would deal with a chain when belts are a thing. Plus, good chains aren't cheap (I like Wippermann) and when you rack up miles you need to replace them enough that your wallet notices.
Tires: +1 for Schwalbe Marathons. Four years and no flats. NB: if you are worried about weight, upgrade to the Marathon Supremes with the aramid (foldable) bead. ~$75USD/each but totally worth it.
Oh yeah: a dynamo hub is a life-changer. My Focus came with a SP PD8 and lights, stock. Never having to strap on a light, or remember to charge it is a revelation.
Ride safe!
Yes I snapped mine within an hour after delivery. It may have been too tightly tensed (tho I did check with the app and it was fine), or it may have experienced stress during shipment. Whatever the case, did not instill confidence. Never rode the bike enough to have much experience with long term reliability, but found the 11-speed IGH didn’t have enough range to cover SF hills appropriately, and shifting wasn’t reliable even after tuning several times - why they chose to implement as a mechanical pulley instead of precise internal system is beyond me. Big purchase regret all around.
This is my experience with my belt drive bike too. It’s a neat novelty and it’s nice having one less chain to maintain. But I wouldn’t use it for rides over a few miles long and changing a flat is more involved.
If you're a tinkerer, and you like swapping tires, doing all your own maintenance, etc, then I agree with you 100%.
However, my bike is my car. I'd no sooner swap out my own bike tire than I'd swap out my own car tire. Not that I can't, it's just not something I enjoy doing. My hub-geared, belt drive, hydraulic-disc bike is incredibly difficult to maintain... but I also just bring it in to my local bike shop once per winter. That one trip is all the maintenance it needs for the 3200 miles I put on it per year, mostly in the rain. I'd never go back to lubing a chain every week, putting new pads on every month, replacing the chain every 3, etc. 6 months after I bought this bike I gave away my repair stand and it was glorious.
However, my bike is my car. I'd no sooner swap out my own bike tire than I'd swap out my own car tire. Not that I can't, it's just not something I enjoy doing. My hub-geared, belt drive, hydraulic-disc bike is incredibly difficult to maintain... but I also just bring it in to my local bike shop once per winter. That one trip is all the maintenance it needs for the 3200 miles I put on it per year, mostly in the rain. I'd never go back to lubing a chain every week, putting new pads on every month, replacing the chain every 3, etc. 6 months after I bought this bike I gave away my repair stand and it was glorious.
>I'd no sooner swap out my own bike tire than I'd swap out my own car tire.
In my neighborhood I get a flat every other month. If I had to pay someone else to replace inner tubes it'd cost as much as driving a car.
In my neighborhood I get a flat every other month. If I had to pay someone else to replace inner tubes it'd cost as much as driving a car.
What tires do you run? That'll happen to me unless I run touring tires. With Schwalbe Marathons front and back, I never get flats.
Continental Top Contact II 37mm front, Continental GP Urban 35mm rear. (Rear fender has less clearance)
You can see my (lengthy) post here about my experience with belt drive, but I was CONSTANTLY getting flats on my Ghost; tried the tires it came with, added tire liners, added slime tubes, nothing worked well until I got the (heavy as a tank) Schwalbe Marathons. Now I want to get the slime tubes out but don't want to remove the tire to do so. But yeah, another vote for "not changing your own tires isn't really an option". Even though its virtually impossible to change tires 'in the field' on my ghost.
There are also very tough plastic liners you can put between the tire and the inner tube. At some point picked up a 1 cm cut in the the tire that this inner layer not only prevented a puncture but kept the whole tire/tube/wheel together until I noticed it by happenstance weeks later. Search for Mr. Tuffy liner but there are others.
Tried them, felt bad, was harder to drive. The same goes for stuff like Schwalbe Marathon. When i look back into the times where i bicycled more, i wonder how i managed with the tires which had just a thin mesh of wires embedded? I feel like the
modern stuff has more planned obsolescence built in. Tubeless makes no sense economically to me, so i go with a small can of breakdown spray.
Have you tried tubeless? I've run them on mountain bikes for yonks, and have now done so on my (non-racing) road bike for about 2 years now with very few complaints. (My race-race bike is fitted with tubs)
They can be messy, but I've lost count of the number of self-healed punctures I've had over the years. A small loss of pressure and off you go.
They can be messy, but I've lost count of the number of self-healed punctures I've had over the years. A small loss of pressure and off you go.
+1 for tubeless -- I switched a few weeks ago after getting sick of weekly punctures in Phoenix -- already saved me a boatload of time and trouble.
Currently running WTB Venture 47c [changed from Horizons] on a 650b 'gravel bike', fantastic stuff, gets me where I wanna go.
Currently running WTB Venture 47c [changed from Horizons] on a 650b 'gravel bike', fantastic stuff, gets me where I wanna go.
I’m going to go out on a limb and guess that you are American. If you have quick release wheels and a new tube (rather than patching the old) you can literally replace a tube in 4 minutes. I’ve timed it.
If your bike is your main form of transport and you can’t change tubes, you need to have two bikes. Unless you live next to a 24 hour bike shop...
If your bike is your main form of transport and you can’t change tubes, you need to have two bikes. Unless you live next to a 24 hour bike shop...
> If you're a tinkerer, and you like swapping tires, doing all your own maintenance, etc, then I agree with you 100%.
Oh no not at all! I hate swapping tires. I live in an expensive and cold country. Swapping bike tires costs $50. I couldn’t afford that twice a year (because of winter tires) I have to do it out of desperation which is why it’s more work than the maintenance benefit I get.
Oh no not at all! I hate swapping tires. I live in an expensive and cold country. Swapping bike tires costs $50. I couldn’t afford that twice a year (because of winter tires) I have to do it out of desperation which is why it’s more work than the maintenance benefit I get.
It's interesting, for sure. I've now commuted on 2 belt-drive systems. I wanted to love it. I'm settling more solidly for "mostly like".
I bought a Ghost brand bike at REI (they're a German brand, but REI is the exclusive US distributor). The model is an "Urban" of some sort, can't remember which. It has an 8 speed Shimano Alfine internally geared hub. I really wanted a Spot Acme (made in Colorado) that was absolutely gorgeous, 11 speed hub, Gates Carbon drive, brooks leather saddle, etc. But that $2k+, and the Ghost was on sale from 1300ish to $850 if I recall correctly. It didn't have a dyanamo so I bought a Shutter Precision hub and had a local bike shop build up a wheel with a dynamo so I could run lights.
The Ghost came with a Continental belt drive instead of the Gates. Instead of having the center groove of the Gates, the continental just... stays in place. Hopefully. The right side of the crank had a flange, and the left side of the hub gear had a flange, but the belt could technically fall off the 'other' side of either one. And it did, occasionally.
Belt tension is regulated by how "tight" you make it by adjusting the rear wheel in place. The Ghost frame has angled dropouts sorta like a normal road bike (not horizontal dropouts like a motorcycle or like the Spot bikes I saw). It's a COLOSSAL pain in the ass for the average person to hold a heavy geared hub wheel in place with one hand, thread the nuts on with your second hand, use a wrench to tighten the nuts with your third hand, and deal with belt tension with your 4th hand. Not to mention keeping the wheel straight. And if you don't get the tension right (how many lbs of tension for a 1 inch drop, again?) the belt will fall off. Repeatedly.
Another problem is that you need to unhook the shifter to remove the wheel. It's not that hard, but when you're a novice to these bikes, it's tricky because some models recommend you shift to the lowest gear; others to the highest. You need some needle-nosed pliers and some finagling to get the cable out.
A problem specific to the Ghost was that the rear disc brake rotor ran into the caliper as you tried to slide the wheel out. So you ALSO have to unbolt the caliper to remove the rear wheel. Overall, it's a vastly bigger pain in the ass to remove the wheel on that bike than on a "normal" bike. God help you if you have a flat on the side of the road. I went through a bunch of different tube/tire combinations before I ended up with slime tubes, which i now HATE because the valve stem gets gummed up and leaks constantly, but I've spent a year or more dealing with it (adding air every week or so) because I'm too lazy to go through the hassle of removing the rear wheel to take out those godawful leaky slime tubes. (but at least I found a tire that's great and puncture-proof!)
Anyway, back to the drive belt. After owning the bike for roughly 5 months and 1000 miles, while trying to cross a busy street, the belt snapped. I tried to source a replacement, but couldn't. I took the biek back to REI, where it sat for the better part of a month while they tried to find parts.
To their credit, Ghost had discontinued use of the Continental system in favor of Gates, and as a goodwill gesture, they replaced the entire drive system of my bike with the Gates drive system.
Knock on wood, the Gates system has been perfect, doesn't squeak like the continental system does, apparently isn't as picky about belt tension, won't slide off (because of the center groove).
The shifting is less than perfect but I like the fact that geared hubs can shift in reverse, so you can downshift at a stoplight while waiting for a green. The spacing between the gears is a bit uneven, but I think it's a pretty good low-maintenance solution for a commuter bike.
But it's not perfect.
I bought a Ghost brand bike at REI (they're a German brand, but REI is the exclusive US distributor). The model is an "Urban" of some sort, can't remember which. It has an 8 speed Shimano Alfine internally geared hub. I really wanted a Spot Acme (made in Colorado) that was absolutely gorgeous, 11 speed hub, Gates Carbon drive, brooks leather saddle, etc. But that $2k+, and the Ghost was on sale from 1300ish to $850 if I recall correctly. It didn't have a dyanamo so I bought a Shutter Precision hub and had a local bike shop build up a wheel with a dynamo so I could run lights.
The Ghost came with a Continental belt drive instead of the Gates. Instead of having the center groove of the Gates, the continental just... stays in place. Hopefully. The right side of the crank had a flange, and the left side of the hub gear had a flange, but the belt could technically fall off the 'other' side of either one. And it did, occasionally.
Belt tension is regulated by how "tight" you make it by adjusting the rear wheel in place. The Ghost frame has angled dropouts sorta like a normal road bike (not horizontal dropouts like a motorcycle or like the Spot bikes I saw). It's a COLOSSAL pain in the ass for the average person to hold a heavy geared hub wheel in place with one hand, thread the nuts on with your second hand, use a wrench to tighten the nuts with your third hand, and deal with belt tension with your 4th hand. Not to mention keeping the wheel straight. And if you don't get the tension right (how many lbs of tension for a 1 inch drop, again?) the belt will fall off. Repeatedly.
Another problem is that you need to unhook the shifter to remove the wheel. It's not that hard, but when you're a novice to these bikes, it's tricky because some models recommend you shift to the lowest gear; others to the highest. You need some needle-nosed pliers and some finagling to get the cable out.
A problem specific to the Ghost was that the rear disc brake rotor ran into the caliper as you tried to slide the wheel out. So you ALSO have to unbolt the caliper to remove the rear wheel. Overall, it's a vastly bigger pain in the ass to remove the wheel on that bike than on a "normal" bike. God help you if you have a flat on the side of the road. I went through a bunch of different tube/tire combinations before I ended up with slime tubes, which i now HATE because the valve stem gets gummed up and leaks constantly, but I've spent a year or more dealing with it (adding air every week or so) because I'm too lazy to go through the hassle of removing the rear wheel to take out those godawful leaky slime tubes. (but at least I found a tire that's great and puncture-proof!)
Anyway, back to the drive belt. After owning the bike for roughly 5 months and 1000 miles, while trying to cross a busy street, the belt snapped. I tried to source a replacement, but couldn't. I took the biek back to REI, where it sat for the better part of a month while they tried to find parts.
To their credit, Ghost had discontinued use of the Continental system in favor of Gates, and as a goodwill gesture, they replaced the entire drive system of my bike with the Gates drive system.
Knock on wood, the Gates system has been perfect, doesn't squeak like the continental system does, apparently isn't as picky about belt tension, won't slide off (because of the center groove).
The shifting is less than perfect but I like the fact that geared hubs can shift in reverse, so you can downshift at a stoplight while waiting for a green. The spacing between the gears is a bit uneven, but I think it's a pretty good low-maintenance solution for a commuter bike.
But it's not perfect.
Was a fan of Dynamic Bicycle's earlier (now discontinued) version of this, but not to the point of ever riding or buying one. They used an internal hub gear for shifting:
http://web.archive.org/web/20160124015048/http://shop.dynami...
(2018)
Thanks for actually pointing this out, when I read the article I thought I'd seen the exact same concept bike in a Global Cycling Network (GCN) video last year. Makes sense.
I'm an enduro and downhill rider myself, and I don't see these coming anytime soon to the "mountain bike" world. Looks fragile and susceptible of failure under high forces and dirt/mud.
I agree. I couldn't see it surviving many pretty routine - well, routine for me - crashes.
I actually thought they had the potential to keep more mud out than a conventional chain.
A conventional chain could be caked in mud, but it literally cleans itself - the contact points anyway. Also, if well-lubricated they're pretty good at keeping water and such out of the internals as well - or at least easy enough to clean up when you get home.
I am waiting for gearboxes to become competitive with derailleurs. Would totally be up for getting rid of that fragile and expensive part.
>I am waiting for gearboxes to become competitive with derailleurs
You mean the internal gear hubs?
They've been competitive for over a hundred years[1].
I had a bike with an 8-speed SRAM[2], it worked fine (got stolen one day).
[1]https://www.sheldonbrown.com/internal-gears.html
[2]https://www.sheldonbrown.com/sram-g8.html
You mean the internal gear hubs?
They've been competitive for over a hundred years[1].
I had a bike with an 8-speed SRAM[2], it worked fine (got stolen one day).
[1]https://www.sheldonbrown.com/internal-gears.html
[2]https://www.sheldonbrown.com/sram-g8.html
Not in the hub, bad for unsprung mass. In the bottom bracket like this
https://pinion.eu/en/
But has some tradeoffs that mean it isn't quite there yet.
https://pinion.eu/en/
But has some tradeoffs that mean it isn't quite there yet.
I think one of the biggest problems is as the rear cassette shifts toward a larger gear, flex could become an issue. The driveshaft will push out on those larger gears making the 'disc' flex toward the wheel. Those larger gears are where you'd be when climbing a hill - where you're typically putting out a good bit of power too.
It's a great idea, and I do love innovation. I've honestly never really had a problem with a chain though, myself.
I have about 6,000 miles on my cross bike (that gets used in some pretty dirty, dusty, sometimes-muddy conditions). And maybe 2400 on my newer road bike. I just clean the chain with wd-40 when it's dirty (sometimes water/soap first if really muddy), dry it well with a rag, then apply some liquid chain lubricant (sometimes after every ride, if it's needed).
It's a great idea, and I do love innovation. I've honestly never really had a problem with a chain though, myself.
I have about 6,000 miles on my cross bike (that gets used in some pretty dirty, dusty, sometimes-muddy conditions). And maybe 2400 on my newer road bike. I just clean the chain with wd-40 when it's dirty (sometimes water/soap first if really muddy), dry it well with a rag, then apply some liquid chain lubricant (sometimes after every ride, if it's needed).
Their motivation is not to reduce maintenance but to increase efficiency.
"[...] the company had already pushed the envelope with lubrication, bearings and pulleys about as far as possible — creating a roughly 98% efficient driverain"
“The quest was, how can we get a 99% efficient drivetrain?”
"[...] the company had already pushed the envelope with lubrication, bearings and pulleys about as far as possible — creating a roughly 98% efficient driverain"
“The quest was, how can we get a 99% efficient drivetrain?”
I have more miles than you :-) (14,000) ((I have exclusively biked for over a decade))
But you know what might be an interesting design idea:
Make a shaft drive like this which is centrally aligned. But the bike has TWO rear wheels as closely spaced as possible and the shaft drives a single axle for the rear -- but has more gearing up front...
But make the two rear wheels with a camber such that they angle out slightly such that their centerlines are as clos as possible - allowing for turning to be essentially the same as a single-rear-wheel bike...
But you know what might be an interesting design idea:
Make a shaft drive like this which is centrally aligned. But the bike has TWO rear wheels as closely spaced as possible and the shaft drives a single axle for the rear -- but has more gearing up front...
But make the two rear wheels with a camber such that they angle out slightly such that their centerlines are as clos as possible - allowing for turning to be essentially the same as a single-rear-wheel bike...
I'm curious as to how you would drive both rear wheels with a single central shaft? Both sides would rotate in opposite directions; I can't find a good example to illustrate what I am saying, unfortunately. I trust you understand what I mean.
Now - there might be a way around this, but it would probably introduce more complications and friction to the mix (one way would be to drop/raise the central shaft off-center of the driving wheels centerline, then have separate fore/aft gearing on the shaft to drive the wheels in the proper direction).
Now - there might be a way around this, but it would probably introduce more complications and friction to the mix (one way would be to drop/raise the central shaft off-center of the driving wheels centerline, then have separate fore/aft gearing on the shaft to drive the wheels in the proper direction).
Shoot I think you may be correct. I hadnt thought of that aspect. Maybe it would require the central shaft to rotate a single gear in the forward direction which was attached to via smaller chain that rotates the axle between the two wheels...?
Yeah... basically what you said in the second paragraph of your comment....
This would be a fun design challenge. Anyone Solid on Solid Works want to give it a go???
---
OH . I thin I have it, but I dont know how efficient it would be:
A Worm Gear:
https://i.imgur.com/BgJODdP.jpg
Yeah... basically what you said in the second paragraph of your comment....
This would be a fun design challenge. Anyone Solid on Solid Works want to give it a go???
---
OH . I thin I have it, but I dont know how efficient it would be:
A Worm Gear:
https://i.imgur.com/BgJODdP.jpg
Here's a solidworks tutorial making a differential gear which is how many/most vehicles solve this problem.
https://youtu.be/qqFTMhubEtc
A differential gear solves both the direction problem and the distance between the wheels when turning problem.
https://youtu.be/qqFTMhubEtc
A differential gear solves both the direction problem and the distance between the wheels when turning problem.
If they enclosed the gearbox, they could add a roller bearing on the reverse side of the sprocket to provide counterpressure to prevent flexing. Enclosing it would prevent grit from getting in as well.
I think they mean the gear (cassette) on the wheel - not the one up at the pedals; there wouldn't be a way to "enclose" that end.
Instead, though - flex might be able to be eliminated by making the "hub" larger, so that the disc (according to the article and renderings, it's a flat and not conical system) has something "solid" on the backside (this isn't shown in the renders from what I could see).
I'm not sure what such a change would do to the performance or handling of the bike, due to the shorter lengths of the spokes to the rim, and the larger mass of the hub, and who knows what else. I haven't been on a bicycle in well over a decade, and even then it was just a cheap Huffy I bought at Walmart for Burning Man use...
So one could say that this technology, even if it were real, would not be targeted at me as a consumer or bike user...
Instead, though - flex might be able to be eliminated by making the "hub" larger, so that the disc (according to the article and renderings, it's a flat and not conical system) has something "solid" on the backside (this isn't shown in the renders from what I could see).
I'm not sure what such a change would do to the performance or handling of the bike, due to the shorter lengths of the spokes to the rim, and the larger mass of the hub, and who knows what else. I haven't been on a bicycle in well over a decade, and even then it was just a cheap Huffy I bought at Walmart for Burning Man use...
So one could say that this technology, even if it were real, would not be targeted at me as a consumer or bike user...
It's never going to work.
What I'm curious about is, how robust is it? How does it handle bumpy rides and rough terrain?
The article doesn't say anything about it and i can't tell
Nor can anyone, because it doesn't actually exist as a product that can be tested. This pops up every few months for some reason, with the same note: The rear shifter is not controllable. A wire to the back half with a bearing to a ring around the drive shaft would solve that, but I'm guessing that messes with their stated high efficiency goal.
Having been dumb enough to use ceramic bearings in a BMX bottom bracket, and in the hubs of a mountain bike... I would not purchase this system.
The replacement rate for those bearings would be astonishing.
The replacement rate for those bearings would be astonishing.
Care to expand this comment? Do ceramic bearings have a higher wear-rate than a traditional steel ball bearing?
Much lower wear and slightly less friction. But they cost roughly 10x as much going from a quality steel bearing. They are marketed as being faster but it's not noticeable in real world conditions. They might be worth it in some non-cycling applications (high precision motors or something). They also break if abused. Steel bearings might deform the balls or dent the race, but they will still turn.
However, as long as there are people with $250 to spend someone will make a $250 set of bearings- don't forget to lube them with snake oil for the fastest results.
However, as long as there are people with $250 to spend someone will make a $250 set of bearings- don't forget to lube them with snake oil for the fastest results.
Hambini has a good article on this[1]. The basic problem (apart from cost) is that only the ball bearing itself is ceramic; the inner and outer races are made of steel and the ball wears a groove into them which increases friction over time. Near the bottom of the article there's a 'power consumption vs kilometres' chart which illustrates this nicely.
"Hybrid ceramic bearings are the equivalent of trying to run a locomotive on an asphalt road - the hardness differential causes the road (raceway) to become damaged."
[1] https://www.hambini.com/blog/post/ceramic-bearings-vs-steel-...
"Hybrid ceramic bearings are the equivalent of trying to run a locomotive on an asphalt road - the hardness differential causes the road (raceway) to become damaged."
[1] https://www.hambini.com/blog/post/ceramic-bearings-vs-steel-...
You fell victim to marketing. Full ceramic bearings tend to shatter. They aren't suitable for high impact applications, and just plain expensive for everything else. Hybrid ceramic bearings (ceramic balls, steel races) are cheaper, but the races will wear out at the rate of steel, so they are an expensive option that needs to be maintained.
Your best value if you want fast bearings is to clean out the grease and replace it with something lighter like sewing machine oil or Bones speed cream. The downside is that you have to maintain it more often because oil doesn't stick around as long as grease does.
Also, the difference between ceramic and regular bearings is on the order of 1 watt. You'd save way more time in a BMX race by wearing tighter fitting clothes, and if you are doing tricks instead of racing then ceramic bearings on a BMX bike makes no sense.
Your best value if you want fast bearings is to clean out the grease and replace it with something lighter like sewing machine oil or Bones speed cream. The downside is that you have to maintain it more often because oil doesn't stick around as long as grease does.
Also, the difference between ceramic and regular bearings is on the order of 1 watt. You'd save way more time in a BMX race by wearing tighter fitting clothes, and if you are doing tricks instead of racing then ceramic bearings on a BMX bike makes no sense.
In my defence I did not pay for those components :) These were companies seeking my endorsement, and I like to put such components to use in the way I enjoy rather than the way they hope.
A little background on this and a thought:
Friction Facts started out as a guy (with an engineering degree) that developed his own test equipment to measure drivetrain losses under load. He eventually published his own wax formulation so that a DIYer could replicate his best effort at reducing chain friction. It produced a chain that had about 4 watts of loss, which is pretty good. That's over 98% efficient for a person putting out 250 watts. 250 watts is high for someone that's never ridden a bike, doable for someone that commutes by bike every day, and a pro wouldn't even break a sweat. So going to 99% improvement, or "reducing friction by 49%" sounds like a lot, but you're only gaining back 2 watts out of 250. Also, Friction Facts felt really cool when is was just a backyard engineer publishing his results, but then he got bought and took all his results/website offline. Luckily the internet archive and many forum posts have the major results, but it felt kind of like he was selling out to the man. I understand that he has bills to pay so I'm not mad at him. I also understand that a regularly lubed bike chain has higher than 4 watts of loss and most people aren't willing to melt wax on their stove to wax their own chains (I do though).
The CeramicSpeed concept couldn't shift in 2018 and they haven't demoed a shifting version as of August 2019. The pie plate at the back is only for looks, and claiming 13-speeds is totally worthless at this point. Heck, I could CNC a 30-speed cog for the back, since it would fit inside the diameter of the wheel. I predict that when a shifting system is functional, it will increase the complexity and add to the friction of the drivetrain, bringing to about the same level of friction as top end chain based systems from Shimano, SRAM, and Campagnolo.
This is a promising idea, but ultimately it's worth more as a way to avoid patent infringement than it is to make a faster bike. Another smaller player, Rotor, makes a 13-speed system that shifts hydraulically. Rotor's marketing claims that hydraulics shift better, but everyone knows that it's just a way to keep from stepping on the established players' toes.
Friction Facts started out as a guy (with an engineering degree) that developed his own test equipment to measure drivetrain losses under load. He eventually published his own wax formulation so that a DIYer could replicate his best effort at reducing chain friction. It produced a chain that had about 4 watts of loss, which is pretty good. That's over 98% efficient for a person putting out 250 watts. 250 watts is high for someone that's never ridden a bike, doable for someone that commutes by bike every day, and a pro wouldn't even break a sweat. So going to 99% improvement, or "reducing friction by 49%" sounds like a lot, but you're only gaining back 2 watts out of 250. Also, Friction Facts felt really cool when is was just a backyard engineer publishing his results, but then he got bought and took all his results/website offline. Luckily the internet archive and many forum posts have the major results, but it felt kind of like he was selling out to the man. I understand that he has bills to pay so I'm not mad at him. I also understand that a regularly lubed bike chain has higher than 4 watts of loss and most people aren't willing to melt wax on their stove to wax their own chains (I do though).
The CeramicSpeed concept couldn't shift in 2018 and they haven't demoed a shifting version as of August 2019. The pie plate at the back is only for looks, and claiming 13-speeds is totally worthless at this point. Heck, I could CNC a 30-speed cog for the back, since it would fit inside the diameter of the wheel. I predict that when a shifting system is functional, it will increase the complexity and add to the friction of the drivetrain, bringing to about the same level of friction as top end chain based systems from Shimano, SRAM, and Campagnolo.
This is a promising idea, but ultimately it's worth more as a way to avoid patent infringement than it is to make a faster bike. Another smaller player, Rotor, makes a 13-speed system that shifts hydraulically. Rotor's marketing claims that hydraulics shift better, but everyone knows that it's just a way to keep from stepping on the established players' toes.
In round numbers, the drivetrain causes about 4 watts of loss.
Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a velodrome and more with knobby, thick mountain bike tires).
The bike itself costs 8 ~60 watts or so in air resistance, less for aero, deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more importantly, air resistance increases with the square of velocity, no matter your starting drag coefficient.
The remaining 150 watts or so are caused by rider air resistance.
And of course, all 250 watts are produced by the rider and dependent on their fitness level.
Clearly, the best way to go faster is to put more energy in. Next, improve your posture to produce less drag. However, it's easier to spend money than to sweat and suffer, so people instead turn to aero bikes, tires, and the drivetrain.
Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a velodrome and more with knobby, thick mountain bike tires).
The bike itself costs 8 ~60 watts or so in air resistance, less for aero, deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more importantly, air resistance increases with the square of velocity, no matter your starting drag coefficient.
The remaining 150 watts or so are caused by rider air resistance.
And of course, all 250 watts are produced by the rider and dependent on their fitness level.
Clearly, the best way to go faster is to put more energy in. Next, improve your posture to produce less drag. However, it's easier to spend money than to sweat and suffer, so people instead turn to aero bikes, tires, and the drivetrain.
>> However, it's easier to spend money than to sweat and suffer
not disagreeing with anything you're saying, however at the super-elite level everyone puts in the maximum amount of perfectly allocated effort into training and preparation. if we could eliminate 4 watts of drive train friction loss that would be material. For your average weekend warrior the points you make are definitely true, but hey, not the worst thing to blow your money on...
not disagreeing with anything you're saying, however at the super-elite level everyone puts in the maximum amount of perfectly allocated effort into training and preparation. if we could eliminate 4 watts of drive train friction loss that would be material. For your average weekend warrior the points you make are definitely true, but hey, not the worst thing to blow your money on...
iirc a single speed or fixed gear setup is already as efficient and the prototype can't change gear anyway...
Here's a picture I took of the 1899 version, in the fascinating bicycle museum in Amsterdam: https://imgur.com/ZnA4kEM
Right, this is about going from 98% to 99%, which is not all that useful. Bearings today are quite good.
Before ball and roller bearings, though, it was really bad.[1]
[1] https://www.youtube.com/watch?v=Peu5hH9vy7E
Before ball and roller bearings, though, it was really bad.[1]
[1] https://www.youtube.com/watch?v=Peu5hH9vy7E
"The first shaft drives for cycles appear to have been invented independently in 1890 in the United States and Britain." (https://en.wikipedia.org/wiki/Shaft-driven_bicycle)
This basic idea has had over a hundred years to take off.
The particular design seen here appears particularly impractical.
The rear shifting mechanism has a poor selection of gear ratios for road use. The gear ratios are not sufficiently close. In my bike I have a Shimano Claris (or Sora?) cassette like this: with 12-13-14-15-17-19-21-23 teeth:
https://i.imgur.com/BFFBYzj.jpg
Even if the drive train has a bit more efficiency, if the gear ratios are bad, that will be a deal breaker, because bad gear ratios wreck the efficiency of the human power plant.
The system has to be extremely rigid for the gears not to skip. If there is any flexibility in the system, it requires massive preload to hold the parts in contact. The chain solves this problem; its own tension binds it to the sprocket teeth.
The rear engagement mechanism has a kind of gear made up of a dozen tiny bearings. Once dirt from road spray gets inside those, they are done.
This is a basically a fair weather toy for yuppies who don't know anything about bicycles.
This basic idea has had over a hundred years to take off.
The particular design seen here appears particularly impractical.
The rear shifting mechanism has a poor selection of gear ratios for road use. The gear ratios are not sufficiently close. In my bike I have a Shimano Claris (or Sora?) cassette like this: with 12-13-14-15-17-19-21-23 teeth:
https://i.imgur.com/BFFBYzj.jpg
Even if the drive train has a bit more efficiency, if the gear ratios are bad, that will be a deal breaker, because bad gear ratios wreck the efficiency of the human power plant.
The system has to be extremely rigid for the gears not to skip. If there is any flexibility in the system, it requires massive preload to hold the parts in contact. The chain solves this problem; its own tension binds it to the sprocket teeth.
The rear engagement mechanism has a kind of gear made up of a dozen tiny bearings. Once dirt from road spray gets inside those, they are done.
This is a basically a fair weather toy for yuppies who don't know anything about bicycles.
My God that’s an ugly crank!
There's a very in-depth talk by Keith Wakeham, arguing that shifting is practically impossible with this system: https://www.youtube.com/watch?v=o9d_cBGXMwY
If I understand it correctly, the issue is that the driveshaft has to move from one "sprocket" to the next in a very small amount of time at high rotational speeds of the cassette. Because of the weight of the bearings at the end of the driveshaft, a very large force is required to accelarate it.
If I understand it correctly, the issue is that the driveshaft has to move from one "sprocket" to the next in a very small amount of time at high rotational speeds of the cassette. Because of the weight of the bearings at the end of the driveshaft, a very large force is required to accelarate it.
1% drivetrain efficiency using fancy expensive fragile materials ... or $100 300W hub motor for effortless commute? choices choices
They put it out as a marketing thing. It had a bunch of impractical caveats.
They haven't announced they solved any of the problems with it in the year since they put it out.
The friction thing & drivetrain is mostly a non-issue. If you're riding fast enough to care the % drag from the chain/drivetrain gets smaller and smaller the faster you go. It's pretty much a non-factor compared to air resistance.
You get way more benefit from doing some extra stretching and yoga so you can lower your handlebars and still ride hard than you do changing to ceramic bearings or fiddling with expensive lubricants or chains/belts/shaft drives.