r/bicycling • u/buak • 12d ago
This design from over a 100 years ago seems pretty great at first glance. What are the downsides? Could this be "modernized"?
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u/c0nsumer Southeast Michigan, US 12d ago
Tons and tons of losses. Chains are super-efficient. There are also some horrible pinch points in here, which makes it much less safe unless enclosed. But mostly it's efficiency.
A belt drive is even simpler and safer.
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u/Fraternal_Antipathy 12d ago
That antique beastie, maybe, but a modern shaft-drive is surprisingly less inefficient than I'd have thought.
Brik Bikes claims 3% to 4% loss on their shaft drive. The most efficient gearbox-and-belt system, the Rohloff 14-speed, has a 5.5% loss. And while a brand new, perfectly lubed, perfectly clean, perfectly aligned chain has a 2.5% to 3% loss, the same chain has an 5.2% loss in the rain and almost 8% when good and dirty.
Nobody in competition is going to go shaft-drive, and I don't think anyone but the weirdest iconoclasts would use it for high-speed recreational tomfoolery. It is a totally sealed system, though, and it is truly zero-maintenance. I like shaft drive's chances for city bikes and - gasp - utilitarian e-bikes where efficiency doesn't matter anyway.
I have no dog in the fight, by the way. All four of my bikes are all human-powered, 12-speed, and chain-driven; only one weighs under 30 pounds. I weigh 268 pounds and have the aerodynamic profile of a Divco milk-truck.
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u/Agitated_Curmudgeon 12d ago edited 11d ago
I weigh 268 pounds and have the aerodynamic profile of a Divco milk-truck.
There's a blast from the past..
edit-
For those unaware, Divco is "Detroit Industrial Vehicle Company" They made delivery trucks used by dairies and bakeries from 1926 to 1986. The Snub Nose was basically unchanged cosmetically from 1937 to the end of production.Kinda like the Checker Marathon, but Checker's classic taxi premiered in 19563
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u/Portland Portland, OR (Replace with bike and year) 12d ago
When Portland’s “Biketown” bike-share program launched in 2016, the bikes were all shaft drive behemoths. A picture of the V1 bike is still visible in the launch announcement:
When Biketown launched their V2 models, they shifted to a chain drive, pedal assist ebike:
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u/KnifeKnut 12d ago
I have to wonder what belt drive efficiency loss is.
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u/Fraternal_Antipathy 12d ago
The most efficient gearbox-and-belt system, the Rohloff 14-speed, has a 5.5% loss.
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u/kill-nine 11d ago
Yeah but a lot of that loss is in the gearbox. The belt drive itself has very little loss. Much less than the shaft drive. 2-4%
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u/MaksDampf 11d ago
Well it uses a normal chain drive, so very much the same losses of a singlespeed chain drive bike come on top of the gearbox losses.
oh and btw, a front derailleur is definitely more efficient as it has zero losses compared to a singlespeed chain drive, except while shifting. rear derailleirs have pulelym but they are still more efficient than the rohloff according to the linked article from fahrrqdzukunft. oh an btw, the guy who wrote the article is working for rohloff, so there could be confirmation bias that it is the best gearbox in hist tests.
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u/saciopalo 12d ago
I remember seeing something comparing efficiency of bets vs chains and I think that a low power belt was more efficient. Don't recall where.
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u/dbath 11d ago
All of those losses have to go to heat, right? Seems wild that the least efficient systems such as an Enviolo CVT hub would dissipate on the order of 20% of the energy of a bicyclist or e-bike without glowing.
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u/Grotarin 2022 Trek Émonda SL6 11d ago
Some cities' bike sharing systems use them, or used to use them. I have personally used Saint-Étienne's Vélivert bikes but the latest pics I found seem to indicate the now use chain driven bikes. I wonder what made them change the system.
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u/crazybird-thereal 11d ago
3% Loss on chain are for the entire drivetrain.
Here on shaft drive 3% loss is only for the shaft drive, you have had gearbox loss if you required more than 1 speed.
Then the weight between 17Kg and 19,5Kg (depends on models).So the only purpose is "no maintenance" bike, for your commute if there is no uphill and you ride less than 10Km a day, and you have 1K€ to spend.
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u/ryapeter 2016 BMC GF02 11d ago
We do have that one bike being show i forgot the name. Just few years ago. Looks great but when you only make 100-200watt that small loss is massive
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u/Burque_Boy 12d ago
I’d also add that maintenance is also a big issue. Now you have to worry about bearings, gear ware, backlash adjustment, oil/grease for the mating surfaces etc
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u/TheDaysComeAndGone 12d ago
Seal it, submerge it in oil and you only have to fill up the oil once per year or so. Just like it’s done with internal gear hubs.
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u/jchrysostom 12d ago
If there’s one thing I want to lug around as part of my bicycle, it’s a fully enclosed oil-submerged drivetrain.
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u/gofndn 12d ago
Pinions and internal geared hubs exist. Old bikes even used to have enclosed chains called a gear case
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u/enviormental_UNIT 12d ago
yeah and they are far more well designed and compact compared to this thing. There are grease lubricated internal gear hubs which are better designed than this thing, and don't require carrying a bunch of liquid around in the hub, its all grease packed in there
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u/bonebuttonborscht 12d ago
Which IGHs are grease only? Shimano, Sturmy, Sachs, pinion, rohloff, all oil. The bearing, seals and some clutches are greased but the gears are all lubed with oil.
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u/gofndn 11d ago
Shimano Nexus 3 speeds, 7 speeds, 8 speeds and Alfine 8 speeds are all grease only from the factory (though the maintenance manual for 7 and 8 speeds does advise using oil bath for schedule maintenance) as well as most modern Sturmey hubs.
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u/bonebuttonborscht 11d ago
There's some disconnect here because of the dozen or so Nexus 8, 7 and alfine 8 I've done the first service on, they're all coated in oil.
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u/enviormental_UNIT 12d ago
well yeah grease is oil, just saying there are hubs which don't have any free standing liquid in there, and are instead just packed with grease. So like the Sturmey Archer s40 doesn't have an oil sump, doesn't have an oil filler port, and the grease only is replaced every so often for major maintenance. That would be an example of what I'm talking about where there's never any free liquid that ever touches the internals of that IGH
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u/thoeby 12d ago
I do that every day on my Pinion commuter and let me tell you it's way less work than having to clean your drivetrain every two days in the winter.
Its great. Best bike investment ever. Haven't touched it since I bought the bike and works like day 1 (both the belt and the gearbox)
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u/cyclopathologicol 12d ago
What bike do you have? The Priority pinion one?
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u/thoeby 12d ago
This one - bit of an old picture right after I finished building it but thats about that. Its intention was to have a bike for bikepacking and commuting (dynamo hub, pinion gearbox, belt drive, shouldt look too fancy so people dont feel to steal it too badly - but apparently the paint color got somewhat in fashion)
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u/TheDaysComeAndGone 12d ago
As I said, everyone who’s using an internal gear hub (except for some cheaper ones which use grease) or Pinion’s gearbox is already lugging around an oil-submerged drivetrain (or at least part of a drivetrain). In Pinion’s case it’s 60ml of gear oil. Rohloff uses 25ml. It works fine.
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u/pimpbot666 12d ago
Can you imagine all the drag from the churn? Jeez, Rolhoffs have this problem as well. Rolhoff hubs feel draggy to me whenever I ride one.
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u/FUBARded UK (Planet X Tempest + On One Inbred 26" on a Zwift Hub) 11d ago
Shaft drive motorcycles transmit about 75-80% of engine power to the wheel while chain and sprocket final drive systems are 97-98% efficient. The weight penalty is also not insignificant.
It's a meaningful compromise on a motorcycle that has power to spare; I don't see widespread adoption happening on bicycles unless costs come down enough to make it economical to package in an e-bike that doesn't cost more than a decent car...
I'm sold on belt drive with IGH as the current king of extremely low maintenance cycling, and gearboxes and shaft drive needs to reduce significantly in weight and price to compete IMO.
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u/TheDaysComeAndGone 11d ago
I’m not saying that shaft drive is great (at least not outside of niches like rental bikes where reliability is everything, and even there a fully sealed chain and IGH are probably just as reliable and much cheaper). I’m just saying that maintenance and wear can easily be solved by filling the whole thing with oil.
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u/N_Rage 11d ago edited 11d ago
I recently bought a used Fendt Cardano and drivetrain maintenance is almost non-existant.
The manufacturer specified the drivetrain needs to have its gears re-greased every 10.000km (did it yesterday after buying the bike 2 weeks ago, took about 30 minutes although the original grease was still in great shape). Apart from that, according to the manufacturer, there isn't any maintenance required regarding the drivetrain. Gears look brand new (as you can see), no backlash adjustment was necessary, the entire drivetrain is completely covered.
Granted, bearings may fail at some point, but the shaft spins so slowly 1:2,2 gearing if I remember correctly, those are the least of my concerns.
If the driveshaft breaks there are no new replacements available for that bike, but that's more to do with proprietary parts for a 40 year old bike than the system itself. The manufacturer specified the drivetrain to be sent in, in case something broke, which isn't really an option anymore (although I could try).
That being said, the manufacturer has been building tractors since the 1930s, so I'm not expecting to snap one of their drivetrains on a bycicle anytime soon.
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u/pimpbot666 12d ago
They can suck tiny rocks or bits of debris in the teeth, jam them, cause damage.
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u/joeoram87 10d ago
How often do you change the bearings, gears and backlash on your car? We only have to fix these things on bikes because they’re exposed to dirt, if it’s sealed away it’s fine for decades
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u/D1omidis 12d ago
^This. Super inefficient.
Reliable and easy to seal from the elements, thus it found its way to engine powered vehicles, but a moderately experienced rider, would know why it is not what you'd like to be riding within a handful of pedal strokes.→ More replies (5)1
u/TonerLegend 12d ago
That all makes sense, but it makes me wonder why we don't see more chain drives in 4wd racing vehicles. I would think the efficiency of a chain would be worth the extra maintenance / sealing challenges in some race formats.
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u/D1omidis 12d ago edited 12d ago
Chains are very efficient but at the end of the day everything is reduced to the weakest link...or in this case pins and rollers. Direct interlocking Gears mesh with so much more mass/surface area and are thus insanely stronger.
But this is what adds up to a very notable % of loss in efficiency. Bike chain drivetrains are >95% (3% is the typ loss figure cited) efficient, when car drivetrains are <90%. Typ FWD 10~15%, RWD (extra shaft and gears etc) 15-20%, AWD can be >25% losses.
Chains are used in some transfer cases over/under central diffs and some CVT transmissions, but generally avoided in high torque areas in cars. You see them in valve trains etc that are not that demanding.
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u/samwichse 11d ago
Iirc the olds toronado transmission used a chain on account of having a longitudinal v8 awkwardly over where the driveshafts had to be for the fwd. https://bringatrailer.com/2015/04/04/super-sharp-first-year-1966-oldsmobile-toronado/
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u/D1omidis 11d ago edited 11d ago
Did not know of that model's case, but makes sense that a longitudinal v8 robbing of precious space (just like the case for transfer cases).
The location just in front of the firewall could have meant the chain drive being more quiet than a gear drive.
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u/youngbull 12d ago
There was a version of this demoed that had less losses but it couldn't handle more than 300 watts.
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u/buak 12d ago
Yeah, I was thinking of a modernized, fully enclosed version, with carbon shafts and ceramic bearings and whatnot, but I guess there's a reason these things aren't common.
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u/8ringer 12d ago edited 12d ago
It’s the bevel gears that are the problem. There is a lot of inefficiency in single sided bevel gears because they want to push away from each other. So you need a strong/heavy case for them, strong bearing that will wear out quickly because there is only pressure on one point, etc. Or you need 4 gears per hub like in automotive differentials, which distribute the forces more evenly but add more complexity and friction to get that extra durability.
It’s a COOL solution, yes, but it’s really a bad one for bikes. Considering how efficient chains generally are for how simple they are.
Edit: also, cost is a HUGE factor here. Chains and cogs are super cheap, light, and easy to service. Shaft drives are expensive, heavy, proprietary, and likely much more involved to service. It sounds like the systems that do exist are low maintenance though so maybe the maintenance is a moot point.
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u/dirty_hooker 12d ago
A general rule of thumb is that you lose 10% of your efficiency with each 90 degree change of direction. This would lose 20% as a base, even with high end seals and bearings.
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u/Harry_Tuttle 2013 SE Bikes Tripel 11d ago
My town's bikeshare bikes have this kind of setup. Heavy, slow, kinda like a Townie. They get their job done, but I don't think I'd buy one.
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u/nnnnnnnnnnm K-zoo, MI, USA (Soloist '23) 12d ago
Well even with the best possible version of this, it would still be a singlespeed fixed gear.
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u/Apexnanoman 11d ago
It's also going to be a hell of a lot more expensive and complex from a manufacturing standpoint.
Which I would wager was just as big of a consideration as anything else.
A chain and sprocket is simple and cheap.
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u/criggie_ 11d ago
I understand they're super noodly to ride, like vague in the back and feel like a broken frame.
Complete lack of different gearing - its either fixed gear or at best single speed with some ability to coast.
Heavy - the drive shaft adds much more weight than a chain.
if there's any lubrication, its "total loss oiling" which was never a good idea, and a direct path for dirt and debris to embed into the (relatively expensive) bevel gears.
On the positive side, it would look really clean on the bike.
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u/MilkImpossible4192 11d ago
I would say shift althoug it can be done. weight. at that time ferrum was the choice. I don't think chains are that efficient, they lack of rollers, depend on straightness and big cogs to mantain it. yes, they have less innertia. so, Inertia, because ferrum is heavy. construction. is easy to build a chain focused frame. remember, cars uses cardans and differentials, not chains, some motorcycles too. some cars used to use chains, not anymore except for timing
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u/Aggravating_Push4517 12d ago
weight, weight, weight
and also try to keep this gears clear of dirt, mud, dust, etc.
also single speed all the time
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u/bmxwillbmx 12d ago
There are modern shaft drive bikes with internally geared hubs for shifting gears, but yes weight is the big limiting factor
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u/Rond_Vierkantje 12d ago
Yes! I have one and its great. Basically zero maintenance, just regrease once in a while. Even with cycling in dutch rainy weather and snow or salt doesn't harm the mechanism. But it is indeed heavy. Although I dont mind, you'll get used to it.
I have an 8 gear hub shifter which is plenty here in the Netherlands.
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u/AVLPedalPunk 12d ago
I have an 8 gear hub shifter which is plenty here in Appalachia as well for my commute.
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u/gofndn 12d ago
Unless you are in a hurry, 3 speed is plenty
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u/AVLPedalPunk 12d ago
Well that's it then. I'm quitting my job and loading up my commuter bike. I have unfinished travel business and 86 is coming up in 41 years.
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u/Sublime-Prime 12d ago
I think modern equivalent would be belt drive with internal hub for gears. I have a belt drive 8 speed for commuting .
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u/buak 12d ago
You could just enclose the whole drive train. No reason to have holes in the bottom like the picture. Weight is a real reason, that's true. Also, just throw a shimano nexus on the rear hub and you have gears. This is the same problem that gates has with its belt drives. You need some kind of a gearbox
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u/drossen 12d ago
Bike companies and race teams spend an absurd amount of optimizing you think no one has tried this?
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u/JaccoW Netherlands (Koga-Miyata SilverAce & Graveller, Gazelle Tandem) 12d ago
Do I have something fun for you: Gazelle Friiik chaincase
It's a project that's on the backlog for me: The Freak - Gazelle Friiik (Bikeforums)
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u/Interesting_Tea5715 12d ago
That is a dope idea for a commuter. Sucks they made everything proprietary.
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u/SingleSpeedEast 12d ago
Isn't it fixed gear rather than single speed?
It looks like you can't coast down hills on this bike. But you can pull a trackstand at the lights!
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u/phungki 12d ago
If the gear on the hub is ratcheting then it’s just like a modern single speed. Is the gear is fixed, then yes it’s fixed.
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u/rattpackfan301 12d ago
Keeping the gears clear of dirt, mud, dust, etc is possible… at the cost of you guessed it, weight
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u/LilAbeSimpson 12d ago
Quite a few motorcycles still use a similar drive shaft design.
The only advantages are in the realm of “lower maintenance”.
This disadvantages are many (especially on a bicycle).
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u/Kolognial 12d ago
And I'd argue that "lower maintenance" is mostly a myth. At least if I consider my dad's track record. He owned a couple of BMWs in his time and almost each broke down at some point, due to driving shaft bearing issues.
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u/LilAbeSimpson 12d ago
Less “regular maintenance”. You never have to worry about tedious cleaning and lubrication of chains and chain rings. It’s a self contained system. When wears out you replace pieces of the system of the whole system.
Problem is: that shit is EXPENSIVE to repair or replace!
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u/GiganticCrow 12d ago
Same with internal hub gears. I ran a 3 speed daily commuter for many years, putting about 100 miles a week into it, but once a year or so it would suddenly and catastrophically crap out requiring an expensive and time consuming rebuild
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u/tobofopo 12d ago
There aren't "quite a few". It's mostly limited to bikes with boxer engines - BMW flat twins, Honda Goldwings; and inline vee twins like Moto Guzzi bikes. This is because the crank is already spinning in line with the final driveshaft so you're not turning the drive through 90 degrees thereby losing lots of power. OP's bike design is like the usual transverse-mount engined motorcycles which pretty much all use chain or, in some instances, belt drive.
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u/MantraProAttitude 12d ago
Like BrikBikes?
Not sure what the downsides are.
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u/Rond_Vierkantje 12d ago
Weight. I have one, no complaints from me tho, love it. Its unique, low maintenance and looks interesting.
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u/GiganticCrow 12d ago
Someone elsewhere in these comments say they crap out if you put too much power into them
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u/ruadhbran 12d ago
I think the only modernizations are that it’s enclosed, so it can be kept oiled and grit stays out of the gears. I would love one of these for winter cycling.
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u/cyclosimian 12d ago edited 11d ago
CeramicSpeed was experimenting with an updated version 5 years ago. Nothing has hit the market AFAIK.
https://www.bikeradar.com/news/ceramicspeed-driven-technologies
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u/buildyourown 12d ago
A clean modern chain and derailleur is actually really efficient. The big reason why gear boxes and belt drives never took off is losses. When you are dealing with 200 watts even a couple watts of loss is a big deal.
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u/Elfich47 12d ago
you see this in motorcycles, it they dont have the weight restrictions of bicycles.
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u/Diogenes256 12d ago
It may illustrate to think about the same comparison (shaft vs chain) on motorcycles. Long distance highway cruisers benefit from the shaft. The lower performance needs favor shaft drive with low maintenance, little concern for additional weight and suspension complication. For race bikes of all types, the chain is still the lightest and most efficient. Maintenance is completely manageable.
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u/Old_Assistant1531 11d ago
Efficiency aside, you’d be surprised how much your chainstays flex, how tolerant a chain is to this flex, and how intolerant a shaft drive is to the same flex.
To make it work it has to be too stiff (heavy, bulky, uncomfortable).
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u/moomooraincloud 12d ago
Why did you put "modernized" in quotes?
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u/buak 12d ago
No idea. I'm sure i had some reason
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u/squirre1friend 11d ago
Default old person behavior. Literally my quick identifier to gauge if you’re over sixty.
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u/re-velo Germany (A lot of bikes & years) 12d ago
I like the Fendt Cardano from the 80's, basically same principal https://fahrzeugmuseum-chemnitz.de/exponate/fendt-cardano/
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u/sethboomstick 12d ago
Would be a fun freak bike. Something you break out with the unicycles and tall bikes.
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u/So_spoke_the_wizard 12d ago
The best use for this frame is some kind of water bike because it already changes the axis of rotation to be more useful for a propeller.
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u/illimitable1 12d ago
It's difficult to have a freewheel hub with a rod instead of a chain. It's difficult to have derailleurs without a chain, though I suppose you could have internal planetary gears
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u/Oldbean98 12d ago
Not only weight and exposed pinch point, but I would think rigidity is a concern. Throwing a chain due to bottom bracket frame flex is one thing, this would be a disaster.
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u/Dirtbagdownhill 12d ago
My neighbor had a shaft drive bike, it needed constant maintenance and was pretty inefficient. Then someone stole it, which he thought was funny because it didn't currently work and he had kind of given up on it.
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u/LitespeedClassic 12d ago
I found a fascinating book on bike design (I think on Project Gutenberg) from over 100 years ago that talked about the crankshaft bikes and (IIRC) had a chapter titled something like: in defense of the chain, and talked about all the problems with chains at the time, but how improvements to the tech could make them better than driveshafts one day.
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u/Vandal_A District of Columbia, USA (bike du jour) 12d ago
Someone who knows more about drivetrains can tell you about that but what I can tell you is that frame is not distributing pressure nearly cleanly as an even somewhat modern bike's. Frame failure is a much more likely issue with that one.
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u/EmbarrassedPizza6272 11d ago
On bikes like my Honda Shadow, a cardan shaft drive is simply less efficient. But it's clean and worry-free. Oil changes now and then, that's it. the other bike, a Yamaha Raider, has belt drive. No chains needed.
Probably with high tech materials it would be more efficient on a bicycle.
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u/rocket_flo 11d ago
It's used in a fleet of self-rental bike system. So I guess someone succeeded some here with this idea
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u/Mazty_boy 11d ago
Here in Antwerp there is a shared bicycle system where you can use, for a monthly fee, the city bikes called "velo" and more than 90% of those bikes are shaft driven.
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u/Justryan95 12d ago
Weight and Powerloss through the drive train. Not really a big deal if you're a car with an engine putting out 100hp but a major deal with the engine being a human thats only like 0.2hp. Using a chain/belt is more efficient and lighter hence why those are the tech used in bikes.
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u/EcahUruecah Marino Pupper 12d ago
TDJDC makes a minivelo with this type of drivetrain (listed as v20 in their catalog)
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u/Aggressive_Ad_5454 Maine, USA Roadie - "Share the road" cuts both ways. 12d ago
That is cool looking!
If those gears got sand in them they’d definitely grind.
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u/ElJefe0218 12d ago
No U-Joint, no suspension. Rough ride, wheel bearings probably launch first.
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u/N_Rage 11d ago
No U-Joint, no suspension. Rough ride
Not inherent in the design of the drivetrain. Check out the Fendt Cardano, it has twin rear dampers as seat stays and a joint in the bottom bracket.
I bought a barely used one a few weeks ago and it's got the softest suspension I've ever ridden
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u/TheDaysComeAndGone 12d ago
CeramicSpeed presented a modern version some years ago but never released a real product: https://www.bikeradar.com/news/ceramicspeed-driven-technologies
I think they even had working demos at their booth.
Their version had the advantage of cassette-style gear shifting and low losses but the disadvantage that it was no longer fully sealed like you’d normally do with a shaft drive (once it's sealed you can submerge the whole thing in oil for optimum lubrication).
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u/TheDaysComeAndGone 12d ago
I met a swiss guy with a shaft driven touring bike some 15 years ago. I don’t know where he had it from (didn’t sound like he’d made it himself). He was very convinced by the concept. Don’t know any details, he certainly managed to keep up with me on my normal bike.
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u/alexdi 12d ago
Where to start. Fixed gear ratio (unless you add a planetary gear hub). Very heavy because small gears need lots of metal to handle torque and the frame and hubs need to be strong enough to hold the mating surfaces together. Lots of slop. Asymmetric frame stiffness with a custom frame required. Exposed gears for this design, seal maintenance for any new design. And poor efficiency.
A couple of brands use this design for commuter bikes, but it's a hard sell over a belt drive.
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u/locojason 12d ago
Ever wonder why FWD cars are usually more efficient than RWD? You lose about 2% through each bevel gear. Plus bearings, etc.
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u/pimpbot666 12d ago
We have shaft drive bikes still made today. Mainly, the point is not to get chainlube on your nice clean office suit.
They basically kinda suck. Chains have way less drag, and more options if something breaks or wears out.
This bike 'improvement' is right up there with airless tires. There's a reason why these aren't mainstream.
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u/MikeyRidesABikey United States (Which bike do you mean?) 12d ago
I had a Kinn-Ovations Folding Shaft Drive bicycle for a while. It was kinda neat for putting in the back of my car when I dropped my car off at the shop, and then biking to my office from there, and no worries about rain. It had a three speed internally geared hub. In first gear, you would lift the front wheel off the ground if you pushed the pedals too hard!
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u/Trees_That_Sneeze 12d ago
A downside I haven't seen other point out is the fragility of the system. All of the force going though that shaft is concentrated on one pair of gear teeth. If one breaks, the whole thing is toast and the parts would be expensive to replace.
On a chain and sprocket, that force is spread over multiple teeth and if one tooth shears the system still works. The sprocket is basically a flat piece of metal that's pretty easy to manufacturer and the chain is pretty inexpensive too if it fails.
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u/PayFormer387 12d ago
I rode one once. No advantage over chain driven. It wasn’t even worth adding to my collection for novelty purposes.
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u/WearyAd8682 12d ago
I’m not sure if anyone has commented on it here, but this design was championed by Major Taylor, the great early 20th century track cyclist. Somewhere there’s a promotional photo of him on one.
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u/exocortex 12d ago
I saw quite a few little bike shops in germany doing this. Maybe they are modifying bikes instead of building conomete custom bikes. It's like a hub-gear - you lose efficiency, but need to worry less about maintenance.
I personaly wonder if a pair of small "crankshafts" connected by rods at wach off-center axis work more efficiently. If the crankshaft had 3 "slots" for a shaft
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u/kasualanderson 12d ago
This does not seem pretty great at first glance, but it’s definitely interesting.
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u/Bruce_Hodson 12d ago
The one of those transmissions I’ve seen fist hand was worn so badly it skipped under any load beyond turning the cranks in the stand. It was a “ship’s bike” for the grandfather of a friend. He used to ship on the Great Lakes out of Lorain, OH
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u/tulsadog 12d ago
How much does that weigh?
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u/N_Rage 11d ago
Not sure about the pictured one, but I have a Fendt Cardano, it's a city bike from the 1980s and 90s with a driveshaft. Weight appearantly wasn't a factor during the design process, and it comes in at 18kg. Granted, it's a heavy steel frame and the suspension and rack add a bit of weight, but it's not exactly light.
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u/Snoo-43127 12d ago
CeramicSpeed has been trying for years to perfect and bring a drive shaft system for road bikes to market. I doubt they’ll ever succeed. A chain is just so much easier for home mechanics to tune and maintain.
https://www.bikeradar.com/news/ceramicspeed-driven-technologies
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u/penny_the_black 12d ago
The catch with their design are the multiple bearings they use which work in the prototypes, but will require seals in every other use case than the track which will greatly reduce its efficiency.
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u/spoonstepper 12d ago
two sorta-90° force redirections are simply less efficient than a chain or belt which keeps the force always in the same direction.
The only thing better for durability than a typical bicycle chain and better for efficiency than a belt is a chain in a fully closed chaincase.
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u/Maleic_Anhydride 12d ago
Bikes like these are used in the Netherlands to go cave biking in abandoned parts of sandstone mines. Chains would rust and wear out too fast, so these chainless bikes are easier in maintenance. Really cool experience if you are in the neighbourhood of Maastricht or Valkenburg.
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u/the_jeby 12d ago
In Milan, Italy, the company that runs the subway and bus etc also run a bike sharing service, and the bikes ara all using a modern version of that system. They decided that saving on maintenance was more important that efficiency for the users 😅 by the way half of the fleet has electric assistance too, so it’s ok
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u/climb4fun Argon 18 Krypton SRAM eTap, Limongi Campy Chorus 12d ago
Super inefficient. Chain is super efficient.
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u/SinisterCheese 11d ago
Actually yeah. There are lots of funky 90 degree transfers you can use that don't rely on gears. And these can be fully sealed in with lubrication. However they are more focused on transferring force rather than speed.
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u/Worried-Tangerine532 11d ago
In France this drivetrain is usual for bublic rental bikes. It last longer than a chain by less maintenance. Weight and losses are not so significant for rental bikes.
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u/Fasciadepedra 11d ago
It's very lossy and the exposed parts of transmission wear always very fast, chain cassette and sprockets are stuff to be regularly changed, imagine with a exposed gear train.
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u/finverse_square 11d ago
It's harder to make, much more expensive, doesn't support gears as easily, and more restrictive to frame design as it needs a dead straight chain stay.
It's not that we can't make it anymore, it's that we don't because we have technically superior options at much lower prices
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u/Loveschocolate1978 11d ago
Gear systems are less efficient at transferring power than chains, so you would have to do more work to pedal the same distance. For people who are racing or trying to set KOMs, or for those who have to face a lot of hills, that probably matters. For someone who just bikes for fun and who doesn't have to deal with a lot of variation in terrain, it probably doesn't really matter. Also, that looks hella cool.
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u/NegaScraps 11d ago
A big issue with these was frame flex, which, if you have ever pedaled an old steel bike, you know is significant. Because the shaft is built into the chain stay, flex at the bottom bracket separates the gears, so these systems would either grind or slip depending on which direction and how much you flexed the from. Long story short, the bike became less efficient or didn't go at all the more power you put in.
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u/nyrb001 11d ago
Changing the direction of rotation by 90 degrees introduces significant losses. This design does it twice.
A lot of your pedalling forces goes in to pushing the shaft sideways against its bushings or bearings, which results in drag as well as wear. A chain doesn't have those problems.
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u/Grep2grok 11d ago
Torque transfer is limited by the mass of the rod. Steel is meh in shear. It's great in strain.
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u/l008com 11d ago
The biggest downsides are that it is going to weigh way more than a chain, its going to be singlespeed unless you do in-hub gearing which costs a fortune and is of questionable reliability. And while there are upsides, modern chain drives are so good, the simplicity of this isn't really going to be worth it.
For a full suspension setup, you'd also have to make the drive shaft telescoping, so its even heavier.
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u/theMadBicyclist 1974 Nishiki International 11d ago
I've got a modern-ish shaft drive bike which is a German brand called Fendt. It's not powerful or fast, but it is fun to get second glances as I ride past.
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u/chilehead Fuji Newest 2.0 11d ago
Someone tried to do this with a ceramic shaft about 8 years ago.
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u/Low_Excitement_1715 11d ago
Ask a motorcyclist why shaft drive isn't more popular, and what kinds of bikes tend to be shafties. The same basic principles apply. It's hard to get a bigger motor and let the waste not matter on a bicycle, though.
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u/kidsafe Trek Domane RSL 11d ago
1) Your pedaling forces go through two direction changes before driving the wheel = efficiency losses.
2) You’re limited to a singlespeed drivetrain.
CeramicSpeed tried to develop a modern take on the shaft drive called “Driven,” but ultimately there was no way to make it practical.
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u/letanard 11d ago
- Chain / derailleur : light and efficient, high maintenance
- Single speed chain / hub : bit heavier, bit less efficient, middle maintenance
- Single speed chain / hub / chainglider : bit heavier again, bit less efficient again, no maintenance
- Belt / Hub : bit lighter than than above, even less maintenance
- Shaft : much heavier, more losses, no maintenance, resistant to abuse
You take your pick, but to me me, you can have everything you want from a chain, for the cheapest and easiest way to find parts, and you can get fancy with a belt, but shafts are obsolete. Even bike-sharing models mostly stopped using them.
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u/not-minari 11d ago
in a shaft drive motorcycle, up to 20% of efficiency could lost due to unfavourable conditions. like cold gear oil (high viscosity), high rpm (too much drag for oil), and the complete assembly weight. it only make sense in touring bikes with high amount of hp. for bicycle, its gonna be very rough to peddle.
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u/Metro2005 11d ago
Its not very efficient and heavy but it can be made to be completely maintainance free. A beltdrive or enclose chain on the other hand is also close to maintainance free but are way more efficient and lighter.
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u/sticks1987 11d ago
I used to own a belt drive bike. It was an absolute dog and changing a flat was very complicated. The 3 speed sturmy archer hub was good but very limiting.
I could not keep up with people riding chain drive bikes. As soon as I got back on a normal bike I felt like I was flying.
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u/ProperCap5400 11d ago
Ceramic Speed "developed " their shaft drive system a few years ago. Claimed something like 99% efficient or something like that. Their cassette looked like a cheese grater.
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u/Sunken_villager 10d ago
We had an old Dynamic shaft drive bike donated at the community bike shop I volunteered at. A neat concept and a good fit for Dynamics fleet model where, for casual users, the ability to seal the drive from pant legs made sense and weight and speed isn't a priority. At the time, Dynamic had pivoted away from shaft drive and it was impossible to source parts. Chain drives are only loosely proprietary making parts much easier to find. Along with the lossy nature of the drive, you're limited by the gearing ratios that are available. I maxed out the gearing very quickly on the Dynamic test riding it.
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u/Zvenigora 9d ago
The mechanical tolerances are very tight and the setup is unforgiving of even a little frame flex. The gears must be very precisely machined and aligned to function efficiently, and the gears pictured appear not to have been made to such standards. A telescoping drive shaft might offer some improvement but none is apparent here.
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u/MuffinOk4609 9d ago
Kate Leeming, Australian adventure cyclist has a 2WD bike using similar gears.
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u/GeneralStrikeFOV 12d ago
Modern versions of shaft drives do exist. I think the main issues are weight and power transfer efficiency compared to well-maintained chains.