11 ms·

CeramicSpeed’s Driven Concept Might Become the Most Efficient Bicycle Drivetrain

95 points by untangle 8y ago

tomglynch 8y ago
Unproven, can't yet change gears, based on an old design used over 100 years ago that was given up on.
- kwhitefoot 8y ago
  > based on an old design used over 100 years Sounds interesting, can you point to some documentation?
woodruffw 8y ago
As mentioned (and slightly buried) by the article, the really fascinating part is that we already have consumer bicycle gears that deliver 97% efficiency: a Dura Ace groupset is expensive compared to the stuff you'll get at Wall-Mart, but they're sold at pretty much every cycling store. I wouldn't be surprised if the Ultegra and 105 (Shimano's next two groupsets by price) were nearly as efficient as well. 2% is nothing to sniff at in cycling (people pay thousands of dollars for that kind of advantage), but there are other factors as well: resistance to stress (sprints), ease of maintenance and service, and weight all factor into the utter dominance of the current groupset design. It'll be interesting to see if CeramicSpeed can advance their design on those fronts.
- hinkley 8y ago
  Can you run torque through two 90° angle changes for less than 3% losses?
  - jacquesm 8y ago
    Depending on how you do it: yes. Look closely, the gear teeth on the driving wheel are miniature roller bearings.
    - hinkley 8y ago
      Are you sure those aren’t bushings? The round bits in a bike chain are bushings, which is part of the efficiency of the existing drivetrain. These folks have essentially turned the chain inside out and attached it to the ends of a shaft.
      - jacquesm 8y ago
        https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images/ceramic-speed-driven00009-1531153680.jpg?resize=768:* https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images... Look closely in that picture you can clearly see the inside of the small bearings.
        hinkley 8y ago
        Well I'll be damned. Them's bearings alright.
        jacquesm 8y ago
        That's also a weak point: those tiny bearings are going to take all the load from the cyclist one or two at the time, I predict they won't last long if it works at all under substantial load. And to reduce friction they're open cage which will not play well with sand and other grime.
  - usrusr 8y ago
    Possibly. They must be getting their idea out 99% from somewhere, and existing transmissions in other application domains are a likely candidate. But I really don't believe that it could work at bike-friendly torque/weight ratios, in a system open to the gritty environment, in a multi-gear setup where angles are not aligned (the inner part of the teeth moves slower than the outer part, permanent slippage, yay). As far as I understand it this is a mockup celebrating the intention of getting to 99, not a prototype that has achieved it. More artist's impression than product. What's still impressive though is that the concept does away with pretty much the only actual product the company has, the pulley wheel. That is bold in a strictly economic way.
- davidgould 8y ago
  > we already have consumer bicycle gears that deliver 97% efficiency: a Dura Ace groupset is expensive compared to the stuff you'll get at Wall-Mart, but they're sold at pretty much every cycling store. I wouldn't be surprised if the Ultegra and 105 (Shimano's next two groupsets by price) were nearly as efficient as well. There isn't really much difference in efficiency with price in group sets until you get into the really bad cheap stuff. Most of the differences are cosmetic or ergonomic and status related. Chains and bearing and cogs are the only items that affect efficiency and they are all pretty good. Good chain line and proper maintenance and lubrication make more of a difference. Internal hubs are slightly less efficient overall and this depends a lot on the internal design and which gears are in use. But even these are something like 94% - 97% efficient. Shaft drives have been the "next thing" since the end of the 19th century but have never managed to combine reliability and efficiency well. I doubt an exposed mesh 90 degree gear set with what look like teeny tiny exposed ball bearings are going to be as efficient after a good splash of water laden with brake dust and road grit. It might work if they enclose the whole system.
  - rienbdj 8y ago
    weight is a big factor between cheap and expensive groupsets
    - magicalhippo 8y ago
      Overheard at a popular stop for bikers near me: "Yeah, I could have gotten the model above it which is 500g lighter, but it would have cost me another $3500." It should be noted that the guy who said it could have easily lost 500g by a minuscule adjustment to his daily snack intake...
      - whafro 8y ago
        No, it should not have been noted.
        magicalhippo 8y ago
- flr03 8y ago
  Wealthy middle-age people and pro now spend fortune to save half a watt so that 2% gain is indeed not marginal at all. Although I tend to be very cautious with manufacturers claims, for some reason especially CeramicSpeed. That being said, I wish them to succeed, as it will bring some fresh air to cycling.
- mrob 8y ago
  >2% is nothing to sniff at in cycling (people pay thousands of dollars for that kind of advantage) 2% is nothing to sniff at only if you're hampered by the arbitrary UCI rules. By far the biggest factor in cycling performance is air resistance, and the obvious solution (fairings) is banned. The UCI has been disastrous for bicycle technology. Most high-end buyers like to pretend they could compete professionally one day, so they abide by the same rules, which means there's no incentive to develop truly fast bikes. The UCI rules should allow any safe design, and avoid giving an advantage to richer teams by setting a price limit (bicycles are already required to be commercially available).
  - woodruffw 8y ago
    I agree that the UCI has been bad for progress. That being said, I raced in college (at the collegiate level, not professionally) and saw plenty of people using UCI-noncompliant bikes. Historically, the UCI did use "safe design" as the metric -- they used it to exclude Graeme Obree, whose bicycle-cum-dishwashing-machine was probably safe enough for him to be riding on a closed track. That's not to say that the UCI should block innovative designs, just to note that they'll use any regulation supplied to restrict cyclists/companies/countries that end up on their naughty list.
  - nerdponx 8y ago
    Do you think there's a market for super-efficient commuter bikes? Or is air resistance no longer the limiting factor at commuter-bike speeds and weights?
    - mrob 8y ago
      I think there's a limited market for them, because the value of aerodynamics depends heavily on how you ride. Wind resistance increases with the square of the speed. Pros can ride at 30mph average on fast stages, where managing wind resistance is huge. A typical road bike commuter might average 15mph. All else being equal that's 1/4th the wind resistance (1/8th the power needed to overcome it), which is still big, but not the overwhelmingly important concern it is for the pros. A commuter on a utility bike who doesn't want to sweat might average only 10mph, so 1/9th the wind resistance (1/27th the power needed to overcome it). At that speed it doesn't feel so important. For the pro, speed is the top priority, but the commuter also has to consider comfort, reliability, and visibility of other traffic (recumbents put your head lower down so it's harder for you to see over cars, and it's harder for them to see you). On heavily congested roads, e.g. central London, traffic might prevent you from going fast enough for wind resistance to be a major concern. If you commute over steep hills then reduced weight might benefit you more. But if you have a long and flat commute with light traffic, I think a super-efficient commuter bike would be valuable, and it's a pity that UCI rules discourage development of super-efficient bike technology. EDIT: added power values as per HankB99's comment.
- tjoff 8y ago
  ... ease of maintenance and service ... Exactly, and gears and chain are horrible in this regard. The absolut vast majority barely maintains their chain which leads to a much lower efficiency and really poor longevity (no it is not hard, but apparently too hard/boring to get done). Unless the owner is a bike enthusiast you can almost guarantee that the maintenance is abysmal. I realized this for myself and bought a belt-driven bicycle so I wouldn't feel bad abusing my current bike. For your day-to-day bike I'm very happy with it and the maintenance benefits alone make it so worth it.
joshontheweb 8y ago
I use a single speed bike at the moment. Not because I hate gears but because I’ve never had a geared bike that didn’t constantly click on the outside gears. It drove me crazy trying to tune them perfectly and never succeeding. Forget increased efficiency. If a new design emerges that accommodates gears and is simple to tune properly, then sign me up. No idea if the design being discussed could offer this.
- oceanman888 8y ago
  I only ride fixed so not an expert on groupsets but people using upper end shimanos does not seem to have that much tunning issue. maybe you yours is damaged or sth?
  - jacquesm 8y ago
    Or mismatched. It's not rare to see people upgrade their bikes with newer gear but to end up with grips that are set for 8 or 9 speed and cassettes and derailleurs with more speeds. That tends to get very awkward.
- nordsieck 8y ago
  Have you tried out a bicycle with an internal hub gear? I don't know how loud they are, but you shouldn't have any chain binding issues (and you could probably run a belt if you wanted).
  - robin_reala 8y ago
    I use a Gates belt drive with a Shimano hub gear and it’s nearly silent compared to a chain.
    - rconti 8y ago
      Oh man, I had a Ghost bike with a Continental drive belt that was a constant pain in my ass until the belt snapped at 1500 miles and practically chucked me in front of traffic. REI really stepped up and Ghost warrantied the entire drive system as the Continental system was NLA; they replaced the whole thing with a Gates Drive system which is amazing.
hinkley 8y ago
Would this design not be... less of a chipper shredder if they switched the cylinders and the teeth?
- King-Aaron 8y ago
  Yeah, I could imagine that getting the end of your jeans or a shoelace caught in that, you're in for a bad time.
  - sliken 8y ago
    Generally if you have shifting, you have a freewheel. If something gets stuck, no big deal, just stop pedaling.
  - jlebrech 8y ago
    heard of covers?
  - hinkley 8y ago
    I suppose you could do a number on your hems, but I’m more worried about feet and calves. I’m thinking about a crash situation specifically. That thing is more of a meat grinder than cogs. Granted, the front chainring is more of a meat cleaver on a traditional bike. I knew a guy who got a nice free tattoo on his right calf. Still gives me the heebies...
AtlasBarfed 8y ago
Yeah, that's going to skip under load and won't stay aligned. Might be usable as an electric assist drivetrain and it was sealed up.
- mirimir 8y ago
  Yes. Based on that photo, I can't imaging that the set of ring gears could be rigid enough. Unless it was inside a strong casing. As in standard differentials.
scns 8y ago
Check these out: https://pinion.eu/en https://pinion.eu/en a german startup which created a gearbox for bikes which works like the one in a car. Early Investment came from an engineer at Porsche. Disclaimer: not affiliated
- bytesmith 8y ago
  Unfortunately, Pinion systems haven't really gained any significant market share due to a) really high cost b) inability to downshift under load, c) a 1.5lb weight penalty and d) the frame must be built specifically for the Pinion system[1]. Still, always great to see new approaches like this as bike maintenance is a huge barrier to adoption. [1] https://www.singletracks.com/blog/mtb-gear/the-pinion-gearbox-solves-common-problems-but-creates-new-ones-a-test-ride-review/ https://www.singletracks.com/blog/mtb-gear/the-pinion-gearbo...
nkristoffersen 8y ago
My grandfather told me about a bicycle he designed that uses a CVT. Curious if that’s a better direction for the future of bicycles.
- voxadam 8y ago
  The problem with CVTs is that they're relatively inefficient.
- jacquesm 8y ago
  You can buy these today, and many e-bikes use them. About 15% power loss means that for an un-assisted bike they are not an option. (Dutch link: https://www.fietsenwinkel.nl/expert-e-bikes/nuvinci https://www.fietsenwinkel.nl/expert-e-bikes/nuvinci with nice cut-out picture of how it works)
bentoner 8y ago
Does anyone know if this would this be UCI legal?
- bytesmith 8y ago
  It's just a concept. CeramicSpeed have said they would like to partner with someone to design the shifting mechanism[1]. [1] https://cyclingtips.com/2018/07/ceramicspeed-driven-drivetrain/ https://cyclingtips.com/2018/07/ceramicspeed-driven-drivetra...
- jacquesm 8y ago
  Not a chance. That gear will rip your leg to shreds in an accident.
  - sliken 8y ago
    Cassettes with similar gear ratios seem just about as leg shredding. Then again anything at 20mph eats legs. I'd rather put my foot or hand into the article's gear, then into the spinning spokes of a wheel.
    - jacquesm 8y ago
      Look closely at the gear: the teeth are standing out on the side at right angles to the plane of rotation and are not protected by the geometry of the frame in any way. That means that they will be very efficient at shredding flesh, far more so than a normal cassette which has the fastest rotating surface closest to the wheel. Obviously you don't want to be in contact with either if you can avoid it. As for the spokes: that's a problem that actually reduces above a certain speed because the spokes will start to act as a plane and throw you out before you can get anything properly wedged. At intermediary speeds they are really dangerous. That's why it is important (especially for kids) to wear proper shoes on bikes and to put spoke guards on the rear wheel where feasible. It doesn't take much to have serious injury of toes or heel, including damage to the Achilles tendon.
  - jlebrech 8y ago
    that gear is perfectly flat-ish and could accommodate a fairing quite easily.
Baeocystin 8y ago
"while the 13-speed rear cog looks like the unholy union of a compact disc and the Sarlacc pit from Return of the Jedi" After looking at the thing, it is a remarkably apt analogy, too. I wonder how long it takes to machine.
pgreenwood 8y ago
If this drivetrain achieves its claims I will be very impressed. Shaft drive designs have been around for as long as chain drives; and they have never been as efficient. So mush is lost in the torsion of the shaft. A 2% increase in efficiency is an absolutely massive gain. The cycling industry is littered with flashy looking innovations that don't live up to the hype. The basic design of a diamond frame and chain drive has not been improved upon for over 100 years. But every now and then there are innovations that acually take hold. For example, the slant parallelogram derailleur, hydraulic disk brakes, suspension (for mountain bikes), and recently narrow-wide front chain rings. We shall see how well this drivetrain goes.
- jacquesm 8y ago
  Shaft torsion does not lose you much energy, it mostly acts as a torsion spring: whatever you put in you will get back. The shaft will only warm up a tiny little bit from the amount of energy that it will lose during a single cycle. Suspension does lose you a lot of energy, which is why you'll never see it on road bikes.
  - usrusr 8y ago
    Springs are terrible when driven by biological "pistons". Applying a certain amount of force is much harder in some phases of the pedal stroke cycle than in others and springs would make it impossible to go easy when you want/need to.
    - jacquesm 8y ago
      It is a very hard spring, not something squishy like front fork suspension. The biggest downside would be eventual wear of the driveshaft, the losses will be very low. Note that almost every part of your bike acts as a spring in that sense, the frame flexes a bit when you pedal, as do the cranks and the shaft. Even the spokes in the rear wheel act as springs transmitting the force from the hub to the rim (which is one reason why they are oriented the way they are, that way they pull the rim along rather than that the spoke gets bent, the spoke is stronger in that direction).
robert_foss 8y ago
Other options include CVT which offer continuous non-integer gear ratio steps, but a lower efficiency of about 79%. http://www.enviolo.com/nuvincicycling/nfinity http://www.enviolo.com/nuvincicycling/nfinity
nottorp 8y ago
They mention something about an electronically assisted shifter. Doesn't that defeat the whole point of a (non electric) bicycle?
- usrusr 8y ago
  Electric shifting is present in high performance cycling for almost a decade now (more if you include failed attempts like the Mavic Mektronic from the 1990ies). It's a roughly 50% split between users who want electronic shifting and users who don't (personally, I don't, I'm pushing more than my share of buttons when I'm not on the bike, I find the refined engineering of a mechanical groupset far more impressive than just throwing microcontrollers at the problem)
- jdietrich 8y ago
  Not really. All three of the major manufacturers offer electronically-controlled derailleur gear systems. It offers minor aerodynamic benefits and more reliable shifting performance with no real weight penalty. The battery adds about 60 grams and the derailleurs are slightly heavier, but the shift levers and cables are significantly lighter. That battery lasts for about 1000 miles of typical riding, which is more than enough for the target market of racing cyclists. The inconvenience and cost of electronic shifting isn't a good fit for leisure and utility cycling, but it makes sense in racing where every marginal gain in performance is valuable.
  - nottorp 8y ago
    Ah well, when I think cycling I don't think racing, I think out-of-town rides where it helps if you're able to fix your bike using just some wrenches...
NietTim 8y ago
This is cool and really fascinating, technically, but ultimately a solution to a question nobody asked and I don't see many benefits outside of a claimed efficiency benefit while there are quite a bit of drawbacks. Also I'm failing to see how this is different from shaft driven bikes [0] we already have had for 'some time' now [0] https://en.wikipedia.org/wiki/Shaft-driven_bicycle https://en.wikipedia.org/wiki/Shaft-driven_bicycle
jacquesm 8y ago
Very nice concept, I really like the fact that the casette is gone because it occupies a lot of space leading to substantial weakening of the rear wheel (the width of the hub where the spokes attach is a very larger factor in rear wheel strength). That gear does look like something that would do well in a meatgrinder, and given the fall-out over just having disc brakes on racing bikes I don't think that would pass inspection for road bike racing. 10 points for out of the box thinking though, a cardan driven racing bike is very clever.
- TheSpiceIsLife 8y ago
  I cardan shaft just another name for a drive shaft? https://en.wikipedia.org/wiki/Drive_shaft https://en.wikipedia.org/wiki/Drive_shaft
  - jacquesm 8y ago
    Sorry, probably a dutchism... We use the same term for the rear end of a car and for the drive train on BMW motorcycles.
kentiko 8y ago
I don't think the big cog will be stiff enough to not bend under the pressure.
bigato 8y ago
> A stock Dura Ace drivetrain returned about 97-percent efficiency. Does anybody know the numbers of efficiency in fixie and single speed bicycles? I reckon they should be better given the absence of a derailler? I tried to search for it, but couldn't find numbers.
- 21 8y ago
  Another article on this technology stated that the efficiency gain comes from there being only 4 points under load versus 8 points in a chain with derailleur system. A fixie also has only 4 points, since the derailleur is gone, so it's presumably more efficient. But the big problem is that there is also an efficient human cadence (I think around 100 RPM), and a fixie has a massive problem here. So overall, a fixie is massively more inefficient. Which I guess is no surprise, cycling competitions are run with geared bikes, not with fixies.
  - bennyelv 8y ago
    This doesn't sound correct to me - the derailleur is on the "slack" side of the chain so is never under significant load. The only load is that required to pull the chain back from the crankset under enough tension to stop it from drooping, which is provided by the spring in the derailleur cage. All the load in the chain system is between the cassette and the chainrings on the top. Perhaps a link to the article will reveal more? There's a lot of BS in bike technology, so I'm automatically sceptical!
    - 21 8y ago
      Maybe load was not the appropriate word to use. Smith explains that that friction in a chain-based drivetrain is created largely at the eights points of articulation, where the chain bends around the chain ring, cassette and pulleys. "Any time a chain articulates, friction is created. And any time it disengages, friction is created," Smith said. "When you think about pedaling 95rpm, you are looking at 40,000 stiction points a minute." In the DrivEn system, those eight points are replaced by four points, each of which rotate on ceramic bearings. The chain ring's teeth and cassette's cog engage with the bearings on the shaft, which itself spins on bearings. https://www.bikeradar.com/road/news/article/ceramicspeed-driven-drive-shaft-52587/ https://www.bikeradar.com/road/news/article/ceramicspeed-dri...
userbinator 8y ago
The system would have to be pretty intelligent to know how fast the system is moving. It’d have to be pretty smart to know how fast it’s moving, which tooth track to select to make the shift happen. Would you have to back off to shift under high load? This reminds me of some newer automatic transmissions that use dog clutches, like a manual one, relying on sensors and electronics to do the synchronisation --- there is a very noticeable (and unpleasant) jerk in the shifts, since it has to match the speeds precisely, and automatically reduces throttle to do so. Of course, with a human providing the power directly, that's not really possible. I suppose you could add a "shift light", but IMHO that's just overcomplicating things...

95 points by untangle 8y ago

tomglynch 8y ago

Unproven, can't yet change gears, based on an old design used over 100 years ago that was given up on.

kwhitefoot 8y ago
> based on an old design used over 100 years Sounds interesting, can you point to some documentation?

woodruffw 8y ago

As mentioned (and slightly buried) by the article, the really fascinating part is that we already have consumer bicycle gears that deliver 97% efficiency: a Dura Ace groupset is expensive compared to the stuff you'll get at Wall-Mart, but they're sold at pretty much every cycling store. I wouldn't be surprised if the Ultegra and 105 (Shimano's next two groupsets by price) were nearly as efficient as well. 2% is nothing to sniff at in cycling (people pay thousands of dollars for that kind of advantage), but there are other factors as well: resistance to stress (sprints), ease of maintenance and service, and weight all factor into the utter dominance of the current groupset design. It'll be interesting to see if CeramicSpeed can advance their design on those fronts.

hinkley 8y ago
Can you run torque through two 90° angle changes for less than 3% losses?
- jacquesm 8y ago
  Depending on how you do it: yes. Look closely, the gear teeth on the driving wheel are miniature roller bearings.
  - hinkley 8y ago
    Are you sure those aren’t bushings? The round bits in a bike chain are bushings, which is part of the efficiency of the existing drivetrain. These folks have essentially turned the chain inside out and attached it to the ends of a shaft.
    - jacquesm 8y ago
      https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images/ceramic-speed-driven00009-1531153680.jpg?resize=768:* https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images... Look closely in that picture you can clearly see the inside of the small bearings.
      - hinkley 8y ago
        Well I'll be damned. Them's bearings alright.
        jacquesm 8y ago
        That's also a weak point: those tiny bearings are going to take all the load from the cyclist one or two at the time, I predict they won't last long if it works at all under substantial load. And to reduce friction they're open cage which will not play well with sand and other grime.
- usrusr 8y ago
  Possibly. They must be getting their idea out 99% from somewhere, and existing transmissions in other application domains are a likely candidate. But I really don't believe that it could work at bike-friendly torque/weight ratios, in a system open to the gritty environment, in a multi-gear setup where angles are not aligned (the inner part of the teeth moves slower than the outer part, permanent slippage, yay). As far as I understand it this is a mockup celebrating the intention of getting to 99, not a prototype that has achieved it. More artist's impression than product. What's still impressive though is that the concept does away with pretty much the only actual product the company has, the pulley wheel. That is bold in a strictly economic way.
davidgould 8y ago
> we already have consumer bicycle gears that deliver 97% efficiency: a Dura Ace groupset is expensive compared to the stuff you'll get at Wall-Mart, but they're sold at pretty much every cycling store. I wouldn't be surprised if the Ultegra and 105 (Shimano's next two groupsets by price) were nearly as efficient as well. There isn't really much difference in efficiency with price in group sets until you get into the really bad cheap stuff. Most of the differences are cosmetic or ergonomic and status related. Chains and bearing and cogs are the only items that affect efficiency and they are all pretty good. Good chain line and proper maintenance and lubrication make more of a difference. Internal hubs are slightly less efficient overall and this depends a lot on the internal design and which gears are in use. But even these are something like 94% - 97% efficient. Shaft drives have been the "next thing" since the end of the 19th century but have never managed to combine reliability and efficiency well. I doubt an exposed mesh 90 degree gear set with what look like teeny tiny exposed ball bearings are going to be as efficient after a good splash of water laden with brake dust and road grit. It might work if they enclose the whole system.
- rienbdj 8y ago
  weight is a big factor between cheap and expensive groupsets
  - magicalhippo 8y ago
    Overheard at a popular stop for bikers near me: "Yeah, I could have gotten the model above it which is 500g lighter, but it would have cost me another $3500." It should be noted that the guy who said it could have easily lost 500g by a minuscule adjustment to his daily snack intake...
    - whafro 8y ago
      No, it should not have been noted.
      - magicalhippo 8y ago
flr03 8y ago
Wealthy middle-age people and pro now spend fortune to save half a watt so that 2% gain is indeed not marginal at all. Although I tend to be very cautious with manufacturers claims, for some reason especially CeramicSpeed. That being said, I wish them to succeed, as it will bring some fresh air to cycling.
mrob 8y ago
>2% is nothing to sniff at in cycling (people pay thousands of dollars for that kind of advantage) 2% is nothing to sniff at only if you're hampered by the arbitrary UCI rules. By far the biggest factor in cycling performance is air resistance, and the obvious solution (fairings) is banned. The UCI has been disastrous for bicycle technology. Most high-end buyers like to pretend they could compete professionally one day, so they abide by the same rules, which means there's no incentive to develop truly fast bikes. The UCI rules should allow any safe design, and avoid giving an advantage to richer teams by setting a price limit (bicycles are already required to be commercially available).
- woodruffw 8y ago
  I agree that the UCI has been bad for progress. That being said, I raced in college (at the collegiate level, not professionally) and saw plenty of people using UCI-noncompliant bikes. Historically, the UCI did use "safe design" as the metric -- they used it to exclude Graeme Obree, whose bicycle-cum-dishwashing-machine was probably safe enough for him to be riding on a closed track. That's not to say that the UCI should block innovative designs, just to note that they'll use any regulation supplied to restrict cyclists/companies/countries that end up on their naughty list.
- nerdponx 8y ago
  Do you think there's a market for super-efficient commuter bikes? Or is air resistance no longer the limiting factor at commuter-bike speeds and weights?
  - mrob 8y ago
    I think there's a limited market for them, because the value of aerodynamics depends heavily on how you ride. Wind resistance increases with the square of the speed. Pros can ride at 30mph average on fast stages, where managing wind resistance is huge. A typical road bike commuter might average 15mph. All else being equal that's 1/4th the wind resistance (1/8th the power needed to overcome it), which is still big, but not the overwhelmingly important concern it is for the pros. A commuter on a utility bike who doesn't want to sweat might average only 10mph, so 1/9th the wind resistance (1/27th the power needed to overcome it). At that speed it doesn't feel so important. For the pro, speed is the top priority, but the commuter also has to consider comfort, reliability, and visibility of other traffic (recumbents put your head lower down so it's harder for you to see over cars, and it's harder for them to see you). On heavily congested roads, e.g. central London, traffic might prevent you from going fast enough for wind resistance to be a major concern. If you commute over steep hills then reduced weight might benefit you more. But if you have a long and flat commute with light traffic, I think a super-efficient commuter bike would be valuable, and it's a pity that UCI rules discourage development of super-efficient bike technology. EDIT: added power values as per HankB99's comment.
tjoff 8y ago
... ease of maintenance and service ... Exactly, and gears and chain are horrible in this regard. The absolut vast majority barely maintains their chain which leads to a much lower efficiency and really poor longevity (no it is not hard, but apparently too hard/boring to get done). Unless the owner is a bike enthusiast you can almost guarantee that the maintenance is abysmal. I realized this for myself and bought a belt-driven bicycle so I wouldn't feel bad abusing my current bike. For your day-to-day bike I'm very happy with it and the maintenance benefits alone make it so worth it.

joshontheweb 8y ago

I use a single speed bike at the moment. Not because I hate gears but because I’ve never had a geared bike that didn’t constantly click on the outside gears. It drove me crazy trying to tune them perfectly and never succeeding. Forget increased efficiency. If a new design emerges that accommodates gears and is simple to tune properly, then sign me up. No idea if the design being discussed could offer this.

oceanman888 8y ago
I only ride fixed so not an expert on groupsets but people using upper end shimanos does not seem to have that much tunning issue. maybe you yours is damaged or sth?
- jacquesm 8y ago
  Or mismatched. It's not rare to see people upgrade their bikes with newer gear but to end up with grips that are set for 8 or 9 speed and cassettes and derailleurs with more speeds. That tends to get very awkward.
nordsieck 8y ago
Have you tried out a bicycle with an internal hub gear? I don't know how loud they are, but you shouldn't have any chain binding issues (and you could probably run a belt if you wanted).
- robin_reala 8y ago
  I use a Gates belt drive with a Shimano hub gear and it’s nearly silent compared to a chain.
  - rconti 8y ago
    Oh man, I had a Ghost bike with a Continental drive belt that was a constant pain in my ass until the belt snapped at 1500 miles and practically chucked me in front of traffic. REI really stepped up and Ghost warrantied the entire drive system as the Continental system was NLA; they replaced the whole thing with a Gates Drive system which is amazing.

hinkley 8y ago

Would this design not be... less of a chipper shredder if they switched the cylinders and the teeth?

King-Aaron 8y ago
Yeah, I could imagine that getting the end of your jeans or a shoelace caught in that, you're in for a bad time.
- sliken 8y ago
  Generally if you have shifting, you have a freewheel. If something gets stuck, no big deal, just stop pedaling.
- jlebrech 8y ago
  heard of covers?
- hinkley 8y ago
  I suppose you could do a number on your hems, but I’m more worried about feet and calves. I’m thinking about a crash situation specifically. That thing is more of a meat grinder than cogs. Granted, the front chainring is more of a meat cleaver on a traditional bike. I knew a guy who got a nice free tattoo on his right calf. Still gives me the heebies...

AtlasBarfed 8y ago

Yeah, that's going to skip under load and won't stay aligned. Might be usable as an electric assist drivetrain and it was sealed up.

mirimir 8y ago
Yes. Based on that photo, I can't imaging that the set of ring gears could be rigid enough. Unless it was inside a strong casing. As in standard differentials.

scns 8y ago

Check these out: https://pinion.eu/en https://pinion.eu/en a german startup which created a gearbox for bikes which works like the one in a car. Early Investment came from an engineer at Porsche. Disclaimer: not affiliated

bytesmith 8y ago
Unfortunately, Pinion systems haven't really gained any significant market share due to a) really high cost b) inability to downshift under load, c) a 1.5lb weight penalty and d) the frame must be built specifically for the Pinion system[1]. Still, always great to see new approaches like this as bike maintenance is a huge barrier to adoption. [1] https://www.singletracks.com/blog/mtb-gear/the-pinion-gearbox-solves-common-problems-but-creates-new-ones-a-test-ride-review/ https://www.singletracks.com/blog/mtb-gear/the-pinion-gearbo...

nkristoffersen 8y ago

My grandfather told me about a bicycle he designed that uses a CVT. Curious if that’s a better direction for the future of bicycles.

voxadam 8y ago
The problem with CVTs is that they're relatively inefficient.
jacquesm 8y ago
You can buy these today, and many e-bikes use them. About 15% power loss means that for an un-assisted bike they are not an option. (Dutch link: https://www.fietsenwinkel.nl/expert-e-bikes/nuvinci https://www.fietsenwinkel.nl/expert-e-bikes/nuvinci with nice cut-out picture of how it works)

bentoner 8y ago

Does anyone know if this would this be UCI legal?

bytesmith 8y ago
It's just a concept. CeramicSpeed have said they would like to partner with someone to design the shifting mechanism[1]. [1] https://cyclingtips.com/2018/07/ceramicspeed-driven-drivetrain/ https://cyclingtips.com/2018/07/ceramicspeed-driven-drivetra...
jacquesm 8y ago
Not a chance. That gear will rip your leg to shreds in an accident.
- sliken 8y ago
  Cassettes with similar gear ratios seem just about as leg shredding. Then again anything at 20mph eats legs. I'd rather put my foot or hand into the article's gear, then into the spinning spokes of a wheel.
  - jacquesm 8y ago
    Look closely at the gear: the teeth are standing out on the side at right angles to the plane of rotation and are not protected by the geometry of the frame in any way. That means that they will be very efficient at shredding flesh, far more so than a normal cassette which has the fastest rotating surface closest to the wheel. Obviously you don't want to be in contact with either if you can avoid it. As for the spokes: that's a problem that actually reduces above a certain speed because the spokes will start to act as a plane and throw you out before you can get anything properly wedged. At intermediary speeds they are really dangerous. That's why it is important (especially for kids) to wear proper shoes on bikes and to put spoke guards on the rear wheel where feasible. It doesn't take much to have serious injury of toes or heel, including damage to the Achilles tendon.
- jlebrech 8y ago
  that gear is perfectly flat-ish and could accommodate a fairing quite easily.

Baeocystin 8y ago

"while the 13-speed rear cog looks like the unholy union of a compact disc and the Sarlacc pit from Return of the Jedi" After looking at the thing, it is a remarkably apt analogy, too. I wonder how long it takes to machine.

pgreenwood 8y ago

If this drivetrain achieves its claims I will be very impressed. Shaft drive designs have been around for as long as chain drives; and they have never been as efficient. So mush is lost in the torsion of the shaft. A 2% increase in efficiency is an absolutely massive gain. The cycling industry is littered with flashy looking innovations that don't live up to the hype. The basic design of a diamond frame and chain drive has not been improved upon for over 100 years. But every now and then there are innovations that acually take hold. For example, the slant parallelogram derailleur, hydraulic disk brakes, suspension (for mountain bikes), and recently narrow-wide front chain rings. We shall see how well this drivetrain goes.

jacquesm 8y ago
Shaft torsion does not lose you much energy, it mostly acts as a torsion spring: whatever you put in you will get back. The shaft will only warm up a tiny little bit from the amount of energy that it will lose during a single cycle. Suspension does lose you a lot of energy, which is why you'll never see it on road bikes.
- usrusr 8y ago
  Springs are terrible when driven by biological "pistons". Applying a certain amount of force is much harder in some phases of the pedal stroke cycle than in others and springs would make it impossible to go easy when you want/need to.
  - jacquesm 8y ago
    It is a very hard spring, not something squishy like front fork suspension. The biggest downside would be eventual wear of the driveshaft, the losses will be very low. Note that almost every part of your bike acts as a spring in that sense, the frame flexes a bit when you pedal, as do the cranks and the shaft. Even the spokes in the rear wheel act as springs transmitting the force from the hub to the rim (which is one reason why they are oriented the way they are, that way they pull the rim along rather than that the spoke gets bent, the spoke is stronger in that direction).

robert_foss 8y ago

Other options include CVT which offer continuous non-integer gear ratio steps, but a lower efficiency of about 79%. http://www.enviolo.com/nuvincicycling/nfinity http://www.enviolo.com/nuvincicycling/nfinity

nottorp 8y ago

They mention something about an electronically assisted shifter. Doesn't that defeat the whole point of a (non electric) bicycle?

usrusr 8y ago
Electric shifting is present in high performance cycling for almost a decade now (more if you include failed attempts like the Mavic Mektronic from the 1990ies). It's a roughly 50% split between users who want electronic shifting and users who don't (personally, I don't, I'm pushing more than my share of buttons when I'm not on the bike, I find the refined engineering of a mechanical groupset far more impressive than just throwing microcontrollers at the problem)
jdietrich 8y ago
Not really. All three of the major manufacturers offer electronically-controlled derailleur gear systems. It offers minor aerodynamic benefits and more reliable shifting performance with no real weight penalty. The battery adds about 60 grams and the derailleurs are slightly heavier, but the shift levers and cables are significantly lighter. That battery lasts for about 1000 miles of typical riding, which is more than enough for the target market of racing cyclists. The inconvenience and cost of electronic shifting isn't a good fit for leisure and utility cycling, but it makes sense in racing where every marginal gain in performance is valuable.
- nottorp 8y ago
  Ah well, when I think cycling I don't think racing, I think out-of-town rides where it helps if you're able to fix your bike using just some wrenches...

NietTim 8y ago

This is cool and really fascinating, technically, but ultimately a solution to a question nobody asked and I don't see many benefits outside of a claimed efficiency benefit while there are quite a bit of drawbacks. Also I'm failing to see how this is different from shaft driven bikes [0] we already have had for 'some time' now [0] https://en.wikipedia.org/wiki/Shaft-driven_bicycle https://en.wikipedia.org/wiki/Shaft-driven_bicycle

jacquesm 8y ago

Very nice concept, I really like the fact that the casette is gone because it occupies a lot of space leading to substantial weakening of the rear wheel (the width of the hub where the spokes attach is a very larger factor in rear wheel strength). That gear does look like something that would do well in a meatgrinder, and given the fall-out over just having disc brakes on racing bikes I don't think that would pass inspection for road bike racing. 10 points for out of the box thinking though, a cardan driven racing bike is very clever.

TheSpiceIsLife 8y ago
I cardan shaft just another name for a drive shaft? https://en.wikipedia.org/wiki/Drive_shaft https://en.wikipedia.org/wiki/Drive_shaft
- jacquesm 8y ago
  Sorry, probably a dutchism... We use the same term for the rear end of a car and for the drive train on BMW motorcycles.

kentiko 8y ago

I don't think the big cog will be stiff enough to not bend under the pressure.

bigato 8y ago

> A stock Dura Ace drivetrain returned about 97-percent efficiency. Does anybody know the numbers of efficiency in fixie and single speed bicycles? I reckon they should be better given the absence of a derailler? I tried to search for it, but couldn't find numbers.

21 8y ago
Another article on this technology stated that the efficiency gain comes from there being only 4 points under load versus 8 points in a chain with derailleur system. A fixie also has only 4 points, since the derailleur is gone, so it's presumably more efficient. But the big problem is that there is also an efficient human cadence (I think around 100 RPM), and a fixie has a massive problem here. So overall, a fixie is massively more inefficient. Which I guess is no surprise, cycling competitions are run with geared bikes, not with fixies.
- bennyelv 8y ago
  This doesn't sound correct to me - the derailleur is on the "slack" side of the chain so is never under significant load. The only load is that required to pull the chain back from the crankset under enough tension to stop it from drooping, which is provided by the spring in the derailleur cage. All the load in the chain system is between the cassette and the chainrings on the top. Perhaps a link to the article will reveal more? There's a lot of BS in bike technology, so I'm automatically sceptical!
  - 21 8y ago
    Maybe load was not the appropriate word to use. Smith explains that that friction in a chain-based drivetrain is created largely at the eights points of articulation, where the chain bends around the chain ring, cassette and pulleys. "Any time a chain articulates, friction is created. And any time it disengages, friction is created," Smith said. "When you think about pedaling 95rpm, you are looking at 40,000 stiction points a minute." In the DrivEn system, those eight points are replaced by four points, each of which rotate on ceramic bearings. The chain ring's teeth and cassette's cog engage with the bearings on the shaft, which itself spins on bearings. https://www.bikeradar.com/road/news/article/ceramicspeed-driven-drive-shaft-52587/ https://www.bikeradar.com/road/news/article/ceramicspeed-dri...

userbinator 8y ago

The system would have to be pretty intelligent to know how fast the system is moving. It’d have to be pretty smart to know how fast it’s moving, which tooth track to select to make the shift happen. Would you have to back off to shift under high load? This reminds me of some newer automatic transmissions that use dog clutches, like a manual one, relying on sensors and electronics to do the synchronisation --- there is a very noticeable (and unpleasant) jerk in the shifts, since it has to match the speeds precisely, and automatically reduces throttle to do so. Of course, with a human providing the power directly, that's not really possible. I suppose you could add a "shift light", but IMHO that's just overcomplicating things...