6 ms·

Driven – A bicycle drivechain concept without derailleurs and chains

45 points by thatcantbeit 7y ago

AstralStorm 7y ago
As far as I'm aware chain was introduced to allow for light weight while keeping vibration resistance. Can't this pulley system be trimmed down even further to one bar transmission?
- hamiltonkibbe 7y ago
  I couldn’t find it on the mobile version of the site but a video of the pinion based drivetrain showed up somewhere else the other day, I think the post is likely in reference to that chain-less system
- falcolas 7y ago
  Based on my experience with motorcycles, chains are better than shafts for transmitting torque. Shafts tend to twist over their length in high torque settings, whereas chains just "pull" with minimal stretching. Specific to this product, how the hell would you keep the 20-30 "gear" bearings on the shaft clean and operating smoothly in anything but lab conditions?
  - jandrese 7y ago
    I have concerns about the longevity of those itty bitty ceramic bearings in real world conditions where you're hitting bumps and cracks in the road while under load from pedaling. Also, literally every part of that page screams "expensive AF" including the part where they don't talk about the price.
  - AmVess 7y ago
    You can seal the bearings, but that cuts efficiency. That's not the only problem, though. The interface between the bearing and the bearing sprocket will make it rather unusable in very dirty conditions. Their setup seems like an answer to a question no one was asking.
    - rhinoceraptor 7y ago
      The gains you could get from improving drivetrain efficiency are very marginal. Everyone else is working on improving aerodynamics. That's the actual limiting factor in cycling, and it always has been.
  - simongr3dal 7y ago
    I was looking at them and scratching my head too. I hope these images are just for show, and that the real product will use shielded bearings or else they are going to get crunchy and destroyed fast.
- kevin_thibedeau 7y ago
  Shaft drive bicycles had their heyday in the 19th century when chains were unreliable.
rhinoceraptor 7y ago
I'm sure this is a neat system, but it's worth noting that bicycles are already very efficient, the difference between their claimed efficiency and a properly set up traditional drivetrain is maybe one or two percent. And any weight savings are probably useless due to the minimum weight required for racing. Pro bikes are basically at the point where they're having to add weight just to pass inspection. This system might have a bit less rotational mass in the "cassette" than a traditional cassette which would help.
- folkrav 7y ago
  I've ridded a half-decent street bike a summer or two. This thing was light enough that as a tall slightly chubby man I felt uneasy just getting on it, I kept thinking "this thing will crumble from my weight". I knew it was stronger than that, but my brain kept telling me something wasn't right. And it was a pretty mid-range bike.
  - LeifCarrotson 7y ago
    As a tall, lean cyclist I'm always a bit surprised by both the extremes that people go to in weight reduction and by the palpable speed difference that you feel when riding a light bike. When I ride a 1980s steel road bike, we (bike+rider) weigh about 75 kg. On a modern carbon-fiber bike, we weigh about 71 kg. That's a 5% difference, but the latter feels like it has rocket boosters when I get out of the saddle to sprint up a climb, while the former feels like I'm carrying an anchor the whole ride. Borrowing a friend's hill climb fixie machine well under the UCI weight limit gives even more of an exhilaration of speed. But conversely, adding 30lbs of bags to go touring doesn't feel that much more difficult once you're up to speed.
    - davidbanham 7y ago
      I wouldn't be surprised if most of that difference in feel could be explained by frame rigidity rather than weight. I love my steel frame but I know it's not super efficient.
kitd 7y ago
Video of it working: https://www.youtube.com/watch?v=UFAQ6CzNm7s https://www.youtube.com/watch?v=UFAQ6CzNm7s
- gvb 7y ago
  The above video doesn't show it changing gears... I was wondering how it did it. It is (sort of) covered in the "fully explained" YouTube video: https://www.youtube.com/watch?v=-9gQ1KRhesM https://www.youtube.com/watch?v=-9gQ1KRhesM Explanation: very complicated with a battery powered wireless electronic shift mechanism embedded in the drive shaft. The "fully explained" video doesn't show it changing gears either, just explains how they would do it. My take-away is that it doesn't change gears as of the making of the video (July 9, 2018) but "they have a plan..."
  - evandev 7y ago
    Correct in the video you reference, they say "this is how we invision the shifting will occur"
jtms 7y ago
Would this system be legal in professional competition cycling?
- notatoad 7y ago
  Probably not, the UCI operates on a policy of all new tech being forbidden until explicitly authorized.
- joerickard 7y ago
  No, this violates current UCI rules. "The front wheel shall be steerable; the rear wheel shall be driven through a system comprising pedals and a chain" However, the rules do change and have been recently (like the removal of the 3:1 restriction).
mbritton72 7y ago
The system isn't ready for prime time, but apparently it's a great way for CS to advertise!
- SlowRobotAhead 7y ago
  I'm not accusing... but I'm struggling to see how this isn't just an ad.
  - lucb1e 7y ago
    For what it's worth, I upvoted the 'story' because I never heard of such a thing and it looks really cool. While I'm a little sad to read that this kind of thing doesn't actually really help, it's not that unexpected. Still, it looks neat, and once the price comes down (I didn't see any prices but I'm guessing it's hundreds for a few metal parts), I might want to play around with such a bike to see for myself. It's a little like other gadgets/gimmicks. (Some gadgets have use, others don't really.)
acomjean 7y ago
chains are a pain. But belt drives have been around for 10 years now and you hardly see them. Chains are the most complex part of the bike with the most moving parts. You have to lubricate them, they stretch.. But they work well in all variety of conditions (even rusty and squeaky) and are fairly cheap. Sheldon Brown's (RIP) bike pages have some good articles on the good old chain. old school html ahead: https://www.sheldonbrown.com/chains.html https://www.sheldonbrown.com/chains.html https://www.sheldonbrown.com/chain-wear.html https://www.sheldonbrown.com/chain-wear.html
- Xylakant 7y ago
  Belt drives are comparatively expensive and don’t work with derailleur gears. Internal gears, especially cheap systems, still cannot offer as many gears as a derailleur. Belts also need to be pretty tight and thus cannot be used on most bicycles with a rear suspension as the distance between the pedals and the sprocket changes under load. So many people opt against belts.
  - blacksmith_tb 7y ago
    I have seen quite a few belts on internally geared hubs - a quick search turns up quite a few[1] commuters shipping w/ belt + Nexus internal hub. 1: https://www.bikeexchange.com/blog/best-urban-belt-drive-bikes-2018 https://www.bikeexchange.com/blog/best-urban-belt-drive-bike...
    - Xylakant 7y ago
      Absolutely: internal gear hubs are the only gears you can use with belts. They just tend to be substantially more expensive for the same amount of gears as a comparative derailleur. Internal gears also tend to have a higher friction than derailleur gears - the really good ones such as a Rohloff speedhub cost > 1000 EUR. Even a comparatively mundane Alfine 11 gear costs ~ 400-500 EUR. A pinion gear isn’t exactly cheap either. In return you get a mostly maintenance free setup. It’s great, but I probably wouldn’t opt for it for a city commuter bike.
  - 7y ago
orliesaurus 7y ago
Honestly, the price-point of these things makes it prohibitive for most people...I wish I could try one for fun though :)
aidenn0 7y ago
I couldn't figure out what it was from the page, but the linked PDF has more information (rolling pinion to what looks like a driveshaft) https://www.ceramicspeed.com/media/2979/driven_brochure.pdf https://www.ceramicspeed.com/media/2979/driven_brochure.pdf
ben7799 7y ago
This company is really famous for selling really expensive "upgrades" that do very little for actual speed. The resistance of the chain & pulleys is a very tiny percentage of the whole unless they're gunked up and not maintained/lubricated or are broken. Pretty much all mechanical resistance on a bike is dwarfed by aerodynamic resistance. When the aerodynamic resistance is broken down the contribution of the bike is dwarfed by the contribution from the rider and his/her body position on the bike. When you start getting into the resistance from gear the helmet & clothes are more significant than the bike. None of this stops them from selling $10,000 bikes to amateurs who are slow though. It is free but hard work to go on a core strength + flexibility program that lets you access more aerodynamic riding posture. Working with a good fitter/coach will cost a little but help get there with less guesswork. Everything about getting fast on a bike is harder work than buying stuff.
- asynchronous13 7y ago
  When people start talking about bicycle upgrades to shave a few ounces here and there, I just point at my belly and the 10's of pounds I could drop from my body before I worry about a couple ounces on my bicycle.
- m463 7y ago
  I think the fastest bikes in a straight line are recumbent bikes because of the small frontal area. Nobody talks about it much (probably because nerdy middle age men are the only demographic with enough devil-may-care attitude to ride one in public)
  - jandrese 7y ago
    Also they're banned in most racing events and horrendously expensive.
    - m463 7y ago
      that's fascinating - I think common bicycles would probably have lots more variants if these hidden administrative rules didn't exist. I'm reminded of the look of sport motorcycles. The design has been heavily influenced by an almost unknown source - a racing rule from many years ago that said the fairing should not extend forward of the front axle.
GhostVII 7y ago
How do they keep the bearings from skipping over the rear gear/disk? That disk and driveshaft would have to be extremely stiff to avoid flexing, especially in lower gears where the contact point is further out, and it looks like just a couple millimeters of flex will give enough space to skip.
freefal 7y ago
First, from an engineering perspective, this product is really cool and maybe for some well-funded Tour de France team it could make sense to test this out. But the price point, the lack of compatibility with components of existing drivetrains and the lack of compelling reasons to make the change, are going to be headwinds to adoption. On page 3 of their brochure (https://www.ceramicspeed.com/media/2979/driven_brochure.pdf https://www.ceramicspeed.com/media/2979/driven_brochure.pdf), they're showing 0.5% - 1.0% efficiency gains over a traditional drivetrain that is cross-chained, meaning that if you use a traditional drivetrain correctly (i.e., shifting so as not to cross-chain) the gains are likely significantly smaller. As ben7799 said, this company is primarily in the business of selling very expensive products that have minimal impact on performance.

45 points by thatcantbeit 7y ago

As far as I'm aware chain was introduced to allow for light weight while keeping vibration resistance. Can't this pulley system be trimmed down even further to one bar transmission?

hamiltonkibbe 7y ago
I couldn’t find it on the mobile version of the site but a video of the pinion based drivetrain showed up somewhere else the other day, I think the post is likely in reference to that chain-less system
falcolas 7y ago
Based on my experience with motorcycles, chains are better than shafts for transmitting torque. Shafts tend to twist over their length in high torque settings, whereas chains just "pull" with minimal stretching. Specific to this product, how the hell would you keep the 20-30 "gear" bearings on the shaft clean and operating smoothly in anything but lab conditions?
- jandrese 7y ago
  I have concerns about the longevity of those itty bitty ceramic bearings in real world conditions where you're hitting bumps and cracks in the road while under load from pedaling. Also, literally every part of that page screams "expensive AF" including the part where they don't talk about the price.
- AmVess 7y ago
  You can seal the bearings, but that cuts efficiency. That's not the only problem, though. The interface between the bearing and the bearing sprocket will make it rather unusable in very dirty conditions. Their setup seems like an answer to a question no one was asking.
  - rhinoceraptor 7y ago
    The gains you could get from improving drivetrain efficiency are very marginal. Everyone else is working on improving aerodynamics. That's the actual limiting factor in cycling, and it always has been.
- simongr3dal 7y ago
  I was looking at them and scratching my head too. I hope these images are just for show, and that the real product will use shielded bearings or else they are going to get crunchy and destroyed fast.
kevin_thibedeau 7y ago
Shaft drive bicycles had their heyday in the 19th century when chains were unreliable.

rhinoceraptor 7y ago

I'm sure this is a neat system, but it's worth noting that bicycles are already very efficient, the difference between their claimed efficiency and a properly set up traditional drivetrain is maybe one or two percent. And any weight savings are probably useless due to the minimum weight required for racing. Pro bikes are basically at the point where they're having to add weight just to pass inspection. This system might have a bit less rotational mass in the "cassette" than a traditional cassette which would help.

folkrav 7y ago
I've ridded a half-decent street bike a summer or two. This thing was light enough that as a tall slightly chubby man I felt uneasy just getting on it, I kept thinking "this thing will crumble from my weight". I knew it was stronger than that, but my brain kept telling me something wasn't right. And it was a pretty mid-range bike.
- LeifCarrotson 7y ago
  As a tall, lean cyclist I'm always a bit surprised by both the extremes that people go to in weight reduction and by the palpable speed difference that you feel when riding a light bike. When I ride a 1980s steel road bike, we (bike+rider) weigh about 75 kg. On a modern carbon-fiber bike, we weigh about 71 kg. That's a 5% difference, but the latter feels like it has rocket boosters when I get out of the saddle to sprint up a climb, while the former feels like I'm carrying an anchor the whole ride. Borrowing a friend's hill climb fixie machine well under the UCI weight limit gives even more of an exhilaration of speed. But conversely, adding 30lbs of bags to go touring doesn't feel that much more difficult once you're up to speed.
  - davidbanham 7y ago
    I wouldn't be surprised if most of that difference in feel could be explained by frame rigidity rather than weight. I love my steel frame but I know it's not super efficient.

kitd 7y ago

Video of it working: https://www.youtube.com/watch?v=UFAQ6CzNm7s https://www.youtube.com/watch?v=UFAQ6CzNm7s

gvb 7y ago
The above video doesn't show it changing gears... I was wondering how it did it. It is (sort of) covered in the "fully explained" YouTube video: https://www.youtube.com/watch?v=-9gQ1KRhesM https://www.youtube.com/watch?v=-9gQ1KRhesM Explanation: very complicated with a battery powered wireless electronic shift mechanism embedded in the drive shaft. The "fully explained" video doesn't show it changing gears either, just explains how they would do it. My take-away is that it doesn't change gears as of the making of the video (July 9, 2018) but "they have a plan..."
- evandev 7y ago
  Correct in the video you reference, they say "this is how we invision the shifting will occur"

jtms 7y ago

Would this system be legal in professional competition cycling?

notatoad 7y ago
Probably not, the UCI operates on a policy of all new tech being forbidden until explicitly authorized.
joerickard 7y ago
No, this violates current UCI rules. "The front wheel shall be steerable; the rear wheel shall be driven through a system comprising pedals and a chain" However, the rules do change and have been recently (like the removal of the 3:1 restriction).

mbritton72 7y ago

The system isn't ready for prime time, but apparently it's a great way for CS to advertise!

SlowRobotAhead 7y ago
I'm not accusing... but I'm struggling to see how this isn't just an ad.
- lucb1e 7y ago
  For what it's worth, I upvoted the 'story' because I never heard of such a thing and it looks really cool. While I'm a little sad to read that this kind of thing doesn't actually really help, it's not that unexpected. Still, it looks neat, and once the price comes down (I didn't see any prices but I'm guessing it's hundreds for a few metal parts), I might want to play around with such a bike to see for myself. It's a little like other gadgets/gimmicks. (Some gadgets have use, others don't really.)

acomjean 7y ago

chains are a pain. But belt drives have been around for 10 years now and you hardly see them. Chains are the most complex part of the bike with the most moving parts. You have to lubricate them, they stretch.. But they work well in all variety of conditions (even rusty and squeaky) and are fairly cheap. Sheldon Brown's (RIP) bike pages have some good articles on the good old chain. old school html ahead: https://www.sheldonbrown.com/chains.html https://www.sheldonbrown.com/chains.html https://www.sheldonbrown.com/chain-wear.html https://www.sheldonbrown.com/chain-wear.html

Xylakant 7y ago
Belt drives are comparatively expensive and don’t work with derailleur gears. Internal gears, especially cheap systems, still cannot offer as many gears as a derailleur. Belts also need to be pretty tight and thus cannot be used on most bicycles with a rear suspension as the distance between the pedals and the sprocket changes under load. So many people opt against belts.
- blacksmith_tb 7y ago
  I have seen quite a few belts on internally geared hubs - a quick search turns up quite a few[1] commuters shipping w/ belt + Nexus internal hub. 1: https://www.bikeexchange.com/blog/best-urban-belt-drive-bikes-2018 https://www.bikeexchange.com/blog/best-urban-belt-drive-bike...
  - Xylakant 7y ago
    Absolutely: internal gear hubs are the only gears you can use with belts. They just tend to be substantially more expensive for the same amount of gears as a comparative derailleur. Internal gears also tend to have a higher friction than derailleur gears - the really good ones such as a Rohloff speedhub cost > 1000 EUR. Even a comparatively mundane Alfine 11 gear costs ~ 400-500 EUR. A pinion gear isn’t exactly cheap either. In return you get a mostly maintenance free setup. It’s great, but I probably wouldn’t opt for it for a city commuter bike.
- 7y ago

orliesaurus 7y ago

Honestly, the price-point of these things makes it prohibitive for most people...I wish I could try one for fun though :)

aidenn0 7y ago

I couldn't figure out what it was from the page, but the linked PDF has more information (rolling pinion to what looks like a driveshaft) https://www.ceramicspeed.com/media/2979/driven_brochure.pdf https://www.ceramicspeed.com/media/2979/driven_brochure.pdf

ben7799 7y ago

This company is really famous for selling really expensive "upgrades" that do very little for actual speed. The resistance of the chain & pulleys is a very tiny percentage of the whole unless they're gunked up and not maintained/lubricated or are broken. Pretty much all mechanical resistance on a bike is dwarfed by aerodynamic resistance. When the aerodynamic resistance is broken down the contribution of the bike is dwarfed by the contribution from the rider and his/her body position on the bike. When you start getting into the resistance from gear the helmet & clothes are more significant than the bike. None of this stops them from selling $10,000 bikes to amateurs who are slow though. It is free but hard work to go on a core strength + flexibility program that lets you access more aerodynamic riding posture. Working with a good fitter/coach will cost a little but help get there with less guesswork. Everything about getting fast on a bike is harder work than buying stuff.

asynchronous13 7y ago
When people start talking about bicycle upgrades to shave a few ounces here and there, I just point at my belly and the 10's of pounds I could drop from my body before I worry about a couple ounces on my bicycle.
m463 7y ago
I think the fastest bikes in a straight line are recumbent bikes because of the small frontal area. Nobody talks about it much (probably because nerdy middle age men are the only demographic with enough devil-may-care attitude to ride one in public)
- jandrese 7y ago
  Also they're banned in most racing events and horrendously expensive.
  - m463 7y ago
    that's fascinating - I think common bicycles would probably have lots more variants if these hidden administrative rules didn't exist. I'm reminded of the look of sport motorcycles. The design has been heavily influenced by an almost unknown source - a racing rule from many years ago that said the fairing should not extend forward of the front axle.

GhostVII 7y ago

How do they keep the bearings from skipping over the rear gear/disk? That disk and driveshaft would have to be extremely stiff to avoid flexing, especially in lower gears where the contact point is further out, and it looks like just a couple millimeters of flex will give enough space to skip.

freefal 7y ago

First, from an engineering perspective, this product is really cool and maybe for some well-funded Tour de France team it could make sense to test this out. But the price point, the lack of compatibility with components of existing drivetrains and the lack of compelling reasons to make the change, are going to be headwinds to adoption. On page 3 of their brochure (https://www.ceramicspeed.com/media/2979/driven_brochure.pdf https://www.ceramicspeed.com/media/2979/driven_brochure.pdf), they're showing 0.5% - 1.0% efficiency gains over a traditional drivetrain that is cross-chained, meaning that if you use a traditional drivetrain correctly (i.e., shifting so as not to cross-chain) the gains are likely significantly smaller. As ben7799 said, this company is primarily in the business of selling very expensive products that have minimal impact on performance.