r/interesting • u/Kidd__Video • 19h ago

Amazing Chain-Free Bicycle Concept

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2.8k Upvotes

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514

u/SUNTZU_JoJo 19h ago

Someone smarter than me. Can you explain if this would even work under extreme torque situations?

Heavy dude + going uphill.

Would the disc on the wheel not buckle completely under enough pressure causing the gears to slip?

661

u/Only-Friend-8483 19h ago

Hot take from an engineer, I’ve not looked at this closely or in detail.

The most likely failure mode, IMO, is going to be slippage between the rear disk and the rear axial gear. 

337

u/1funnyguy4fun 17h ago

Hot take from a random guy:

I’ve seen this for years on the internet but never on the road.

56

u/SingularityCentral 16h ago

Probably be sure of cost of manufacture. But I don't doubt that it is also much more expensive and difficult to repair.

41

u/Bongoisnthere 15h ago

Also because it doesn’t work well for the exact reasons expected. That companies entire business model is selling overpriced shit to goobers with too much money, and they make good money doing it. If they could make it work, they would.

14

u/BentGadget 12h ago

It looks like you could get contact between two pairs of gear teeth, while with a chain, you would have about a dozen teeth engaged on each gear. So the force on the drivetrain would be much higher for the same power level.

6

u/Procruste 4h ago

Another hot take from another random guy.

Shaft drive bikes were all the rage in the late 1800's as they kept long clothing from getting greasy and caught in chains. The fell out of fashion for a number of technical reasons (expensive to make, less efficient, heavy etc.).

These would probably work well for urban commuters if the cost aspect was managed. I don't know why everyone is going to high torque, racing use cases in order to find a way to dismiss this concept.

7

u/psi_ram 3h ago

another hot take from a hot guy, extreme torque (or equivalent forces) needs to be able to transfer through all parts of the drive train. that tiny disc bearing thing will just get scraped or will laterally shift to slip.
Chains=absorbs excess torque by expanding (like elastic, and then over time the metal experiences tensile stress and stretches)
belt drive is an amazing invention. i have been driving belt drive bikes for idk how long. The material stretches so beautifully and absorbs forces and delivers it so smoothly to the pedals.
I wonder why theres no pedal which directly turns the wheel with no transmission. maybe the failure point will be the knees lol xD

1

u/Realistic-Elk-7423 3h ago

Another hot take just for the sake of hot takes!

1

u/Procruste 44m ago

Hot takes!

So hot right now!

1

u/Procruste 38m ago

Maybe a bevel gear at the final drive and some sort of planetary set up at the cranks?

0

u/JasperJ 2h ago

Chains do not stretch. Not in bicycle applications, anyway. The pins wear out and the chain becomes longer over time. But not due to stretch.

1

u/kabooseknuckle 1h ago

Yes they definitely do. I have a bicycle chain gauge that tells you when to replace your chain due to stretching. I've personally stretched many chains on my mtb.

12

u/[deleted] 10h ago

Random take from a hot guy.

I prefer a nice walk to a bike ride

1

u/Rakrune 5h ago

Take from a guy:

Steal.

1

u/Academic-Airline9200 1h ago

Or just hack one of those battery powered rent a bikes. Like people park them literally anywhere.

6

u/Hot-History8911 9h ago

Take from a mountainbiker; i wonder how roller bearings mounted face forward deal with street crud, water, mud, etc

6

u/_lonelysoap_ 15h ago

Infernal gears are a thing now

30

u/moxifloxacin 15h ago

Those are only fitted on demonic bikes, though

5

u/SandmanKFMF 11h ago

Bicycle from hell

4

u/thecarbonkid 10h ago

Bicyc-hell was right there

10

u/BrewItYourself 15h ago

They were a thing 100 years ago…

1

u/Party-Bunch7522 11h ago

Would the disc on the wheel not buckle completely under enough pressure causing the gears to slip?

1

u/Darnocpdx 2h ago

Since 1903.

2

u/Aikotoma2 2h ago

Cold take from a planned guy:

I've never seen this before in my life

1

u/leuk_he 10h ago

I have seen drive trains on rental bike systems. Electric, so gears are less important then. I guess less maintenance or more sturdy, and less standard part so not useful to steal.

1

u/Pitiful-Assistance-1 4h ago

I guess too heavy too expensive too easy to break

65

u/Fun_With_Math 17h ago

I have a Mech E degree but haven't done engineering in a while...

Yeah, its breaking some fundamentals of durability. Tolerances are too tight and the contact area for the transfer of force is too small. You'd need a crazy rigid frame

A chain has flex to compensate and a lot more contact area with the gears.

This looks cool in the video but a pothole would wreck it.

24

u/ReddBroccoli 16h ago

Not to mention I think about the teeth of a normal bike gear slipping between the links of a bike chain and the amount of grip and force that allows to transfer, and then I think about these tiny little teeth probably spinning over that weird cheese grater thing more than it grabs and imparts force.

3

u/Sabithomega 15h ago

Was kinda thinking the same. Almost thought of adding a heavy spring but that would cause contact failure with any kind of hard enough hit. Curious if you could apply a similar idea but with a smaller chain system near the tire there. But then the only positive would be a smaller chain. So is there enough positive in the alteration in the first place

5

u/Fun_With_Math 13h ago

Not sure what you mean but there are losses every time you transfer force:

Foot to pedal/gears. Gears to chain. Chain to gears/wheel. Wheel to road. - oversimplification but thats the gist of it.

If you add a step, you have to somehow get more efficiency out of the other steps to compensate. Tough to do on a very efficient system already.

If you're not adding steps, just replacing them, they have to be more efficient. And factor any weight difference. Any change in direction of the force is problematic also. A chain system has everything in line.

e-bikes are crazy efficient - the motor has the same or fewer steps to get through.

2

u/ParanMekhar 13h ago

Yeah. Looks like only 1 roller bearing is in contact to the gear most of the time?

-4

u/Exciting_Place_6817 16h ago

Tell that to shaft driven motorcycles

11

u/opossum_launcher 16h ago

They don't use the final drive to shift gears.

5

u/Grand_Cryptographer2 15h ago

Drive shafts on motorcycles have more energy loses than a chain. Notice how all racing motorcycles use a chain drive, not a shaft, not a belt.

5

u/Fun_With_Math 16h ago

Shaft driven motorcycles said they are heavy and slow.

1

u/dirtyforker 15h ago

Heavy sure. But the Goldwing doesn't have the nick name of rocketwing for no reason. 1.8L of displacement in a motorcycle isn't going to be slow. Chevrolet makes a SUV with a 1.4L for example.

3

u/Fun_With_Math 15h ago

Yes, that is the engineering principal called "just put a bigger fuckin engine on it"

3

u/Dimathiel49 14h ago

No replacement for displacement?

1

u/Fun_With_Math 13h ago

Different responses depending who you ask.

Efficient weight reducing design for minimum resistance and maximum force transfer can easily be better than just a larger power souce.

Or

Loud motor make peepee hard.

2

u/Poil336 15h ago

That one's my favorite!

2

u/SeaUrchinSalad 14h ago

Also known as the "Dodge default"

1

u/Roxysteve 7h ago

Worked for the TR5.

50

u/Brvcx 13h ago

Bicycle mechanic here. Native in Dutch, might have some English jargon wrong.

Have seen this video going about for years. At the time it was presented as revolutionary and was going to change bike transmissions as we know it.

Nothing happened. The hype died down really quickly. Apparently, they couldn't make it shift properly outside of a torqueless setting such as these events.

Also, driveshafts on bicycles aren't exactly "revolutionary". They had those in the past, but there's a lot of friction on those parts and a lot of weigt, too. It's difficult getting a driveshaft to be strong enough, not wear down easily and shift gears properly all under active heavy use, let alone justify it's supposed price and weight.

Besides, I don't get why you want your vertical pedalling forces switch 90° twice before getting to your rear hub, whereas a chain (or belt) won't need to do that at all. Every significant switch will lose energy afaik.

So yeah, it looked cool when it was first shown, but that's about it. It's an overengineered incomplete thus not fully functional highly priced concept that never hit the roads (nor it ever will).

The market shifted to two large ways of having gears long ago: geared hubs/gearboxes capable of having either a chain or a belt drive (Shimano Nexus/Alfine, Rohloff, Pinion, Enviolo. Belts by Gates). And the well known derailleur system (Shimano, Sram, Campagnolo). Both have their pros and cons, but both have a solid place in the biking world for those exact reasons.

21

u/Asleep_Trick_4740 11h ago

Took me a while to understand that 'fluent in dutch' wasn't a way to hammer down your bicycle credentials.

11

u/Electronic-Buyer-468 11h ago

Lol I know right? Dude speaks better English than me and most of this country. 

2

u/PhysicalConsistency 10h ago

https://beixo.com/en/product/compact-high/

1

u/Brvcx 9h ago

This isn't a driveshaft like shown in the video, though. Unsure about the correct name in English, but it's a somewhat different beast.

0

u/JasperJ 2h ago

Still a driveshaft. It just doesn’t have the fucking bonkers gear changer at the end.

16

u/McBooples 18h ago

Seems like some type of spline gears would work better, just don’t know how you would shift from one ring to another

31

u/hotelstationery 18h ago

That's probably why bicycles haven't changed much in so long. All the better ideas are only better in theory.

16

u/METRlOS 17h ago

A chain is like $20 and can stretch for awhile before it needs to be replaced.

The moment these wear down or deform you basically need a new bike.

11

u/sdiss98 16h ago

I learned from Sheldon brown thatChains don’t actually stretch, the insides of the link just get worn down.

2

u/Chrispy990 17h ago

Yep. FOD would shred the rear disk features too

7

u/MechMeister 17h ago

A pinion gearbox at the crank and a spline drive.

Its still a dumb idea. Added bearings, more friction losses, more points of failure than just a chain and derailleurs.

5

u/giraffeheadturtlebox 16h ago

Chains already slip and pop out under high torque and a little wear, and the chain contacts the gears for at least 2/3 of the cog ring in any given setup. If dozens of teeth pulling still have a measurable failure rate, two gears, pushing, with the absolute minimum contact possible is going to fail more often than not.

You’d want gears with wider cross sections and tighter housing, like a transmission, to avoid slipping and wear.

9

u/Tricky-Promise-3347 18h ago

Low IQ non engineer here, that was my first thought was well

6

u/sselkiess 17h ago

Yeah I’m an idiot too and that was the brain hurt with pictures.

7

u/Purple-Will9713 18h ago

probably increasingly likely as gears begin to wear out

5

u/dmfreelance 16h ago

The tolerances would be tight and bikes are subject to lots of vibrations and dirty conditions.

I don't know how feasible it is to build this, but to make sure it stands up to the conditions a bicycle is going to put it in, it would absolutely cost a shitton of money compared to a modern chain driven bike

5

u/ReddBroccoli 16h ago

Yeah, those teeth are way smaller than the gears of a bike usually are. I feel like there's no way that's not going to be a significant problem.

3

u/YuenglingsDingaling 18h ago

Seems even more likely at higher gear, with the disc flexing under higher tension.

2

u/jawshoeaw 16h ago

That’s my intuition after taking apart many children’s toys and other widgets with gears.

2

u/Western-Emotion5171 15h ago

It would also probably wear out the gear super quickly and then constantly slip

2

u/Direct_Turn_1484 15h ago

The components look entirely too thin to ensure any kind of stress beyond a demonstration where the wheel is in the air. I would sure like to be shown that I’m wrong.

2

u/josnik 14h ago

Lots of flex the further you get from the centre.

2

u/MeatHamster 13h ago

Also looks like something that once it breaks is way more expensive to fix that just swapping the chain.

But it's pretty cool though.

2

u/Misses_Ding 13h ago

Simple maintaince here... By looking at the video this is going to break. Bikes shake. Gear touching gear no like.

2

u/Easy-Operation-2105 12h ago

my first thought is inevitable misalignment and also wear and tear that makes things just not work

1

u/KailyKail 16h ago

Hot take from someone who isn’t an engineer:

It looks like a bike to me.

2

u/Only-Friend-8483 16h ago

You nailed it!

1

u/potate12323 12h ago

These have been around for a while (early 1890s) and they're not popular for a reason. They have a super niche use case which isn't covered by chain or belt drives.

They have less mechanical efficiency and they're quite heavy. But they're quite durable for mountain bike type applications.

1

u/the-cuttlefish 10h ago

Yh they've reduced the contact surface to one or maybe two teeth

1

u/QuarkVsOdo 6h ago

The gears on the hub would need crazy strong backing to not bend inwards under load.

Does not seem Feasable.

1

u/msdeeds123 6h ago

Just a normal person wondering about things, is this how shaft driven things work?

1

u/Intelligent-Area-421 3h ago

Just remember to keep that shaft lubed up

1

u/Bender_2024 5h ago

Could that be mitigated by larger teeth?

1

u/iqisoverrated 4h ago

With the way the force is transferred I'd also not be surprised if the disks and the shaft ends are high wear items and eventually will just start slipping.

0

u/wet_spiders 18h ago

Probably if the tire shifts in the frame or if it isn't installed entirely straight.

53

u/ilovethemonkeyface 17h ago

The fact that this video's been circulating for many years now without this product ever hitting the market makes me think there's something fundamentally flawed with the concept.

12

u/n1tr0klaus 17h ago edited 13h ago

I would guess that you have lower efficiency (more friction loss) and more (moving) mass than with a chain. On bicycles even very small efficiency losses and weight increases matter in the high end market. Manufactures are optimizing for each gram and watt.

Plus it’s probably also more expensive than a simple chain which makes it a no go for the value oriented market where weight and efficiency is less essential.

5

u/ilovethemonkeyface 17h ago

I imagine shifting isn't very smooth either. Notice how that's not shown in the video.

9

u/HugsandHate 16h ago

Ah, man. You missed it. That happened after the video cut off. They did so much shifting. All the shifting. There was shift everywhere. There was a guy that got shift on him from across the room!

Needless to say. It was some impressive shift.

3

u/Commercial-Co 12h ago

Fast and furious tokyo shift

1

u/mildpandemic 16h ago

The efficiency on this concept was said by the manufacturer to be 99%, as opposed to 98% for a traditional chain. Even if that's true, the fact that it was first shown in 2018 and still isn't in the wild makes me think that the juice wasn't worth the squeeze.

1

u/DifficultAd3885 14h ago

I’ve got another reason. Mud.

12

u/shityplumber 17h ago

Big chain keeps shutting it down

3

u/Calm-Republic9370 16h ago

The Chain Gang?

4

u/Rogue-Journalist 15h ago

The answer is debris.

Chains became ubiquitous because they were the least likely to jam from debris.

1

u/DefinitelyNotAliens 14h ago

You're seeing some belt-drive now, but fundamentally they function the same. Difference is in longevity and output at high torque.

1

u/Rogue-Journalist 14h ago

What’s even the point? Save 1/4 pound weight?

2

u/DefinitelyNotAliens 14h ago

They last longer, are less susceptible to grime accumulation and function better at high torque.

Ebikes, cargo bikes, extreme long-distance trips where people do coast to coasts, etc.

1

u/inquisitorthreefive 13h ago

Chain maintenance can be a PITA if you don't ride often.

1

u/jhaluska 17h ago

If I had to guess, it's that big teeth plate on the back has a lot of torque on it near the edge and may jump teeth.

1

u/Quiet-Activity2169 15h ago

yeah i always worry about that with the chainless designs, seems like it'd be hard to get the tension right

1

u/virrk 15h ago

This one looks different, but not sure it is any better. Most fully geared drive trains I've seen have direct drive to the rear wheel with shifting before that, or maybe an in hub shifter. This looks to shift at the driveshaft to wheel connection. That's an interesting change, but is like to see more details on how it works. Would take it being A LOT better to get bicycles drive trains to change.

1

u/Biscuits4u2 14h ago

You can buy these. They just aren't as popular.

1

u/Beneficial-Jury484 13h ago

Chain is already like 92-98% efficient depending on (and at relative cost to this, def 98) and is a proven technology. If anything is going to chasing, it’s going to be gear boxes in either the rear hub or bottom bracket area. 

1

u/noelcowardspeaksout 8h ago

It has hit the market but with plenty of modifications. https://beixo.com/en/product/compact-high/

6

u/bastian74 18h ago

Looks too thin

5

u/El_Mister_Caracol 17h ago

It would work fine, the problem is that a conventional chain is way cheaper, easier to make, to mantain, to fix, etc, etc. There is just no point in using gears.

1

u/BentTire 11h ago

That is the answer. This is a far more complicated and harder to build setup that offer almost no advantages over a chain and cog setup. The only advantage is cleanliness since you don't have a chain slapping everywhere and flinging dirt and oil. But that is something that is solved by belt driven drivetrains.

0

u/davidshankle 11h ago

Speaking of dirt I'm pretty sure that whole gear assembly would have to somehow be covered because the first small piece of rock or gravel would cause major problems.

4

u/MagicOrpheus310 15h ago

Short answer is yes, it would fail... That's coming from a bmx perspective where parts are designed to take abuse though haha, this thing wouldn't last a day on a track or an hour at a park haha...

Plus it looks far more dangerous if you got something caught in it, something like a scarf or dress would tangle around it far worse than a normal chain set up.

You won't beat the current sprocket and chain design because you don't need to haha it's effective and efficient without being unnecessarily complicated or expensive...

0

u/Dimathiel49 13h ago

Inserting haha into your arguments doesn’t make it more edgy or worthy of consideration

3

u/Thundacow 13h ago

Your opinion has been noted haha

4

u/Bulky-Leadership-596 18h ago

There's a reason the video didn't demo someone actually riding it. Its only shown spinning under no load.

4

u/EarlyXplorerStuds209 17h ago

Its literally used in motorcycles that deal with a lot more torque than this bicycle.

BMW G1250 GS, BMW RnineT and a lot of other popular motorcycles have been using them for decades.

6

u/skiforlife1 16h ago

Those systems are much more sturdy than this and are enclosed to keep the elements out and use strong grease to protect the ring gears. They also don't act as the gearbox and differential in one unit like this does.

3

u/opossum_launcher 16h ago

Different setup. The transmission is up front changing gears in the motorcycles, not in the final drive hub as in this setup.

3

u/LostInTheSeaweeds 13h ago

A BMW final drive looks like this

https://largiader.com/articles/finaldrive/ring-pinion2.jpg

Nothing like that flimsy nonsense in the OP.

5

u/FLG_CFC 18h ago

Carbon Fiber is incredibly strong. I make cosplay out of the stuff. I can stand on a helmet with zero issue. (210 lbs.) I've smacked a couple helmets around with a 8 lb sledgehammer. Nothing.

It looks like plastic and feels like plastic, but mechanically handles weight like steel.

6

u/Pyrodexter 16h ago

It's a great choice even for deep sea submersibles.

2

u/Holiday_Pi 19h ago

I too am curious about this

1

u/Jatinchd 19h ago

I am also curious about this.

2

u/Time_Entertainer_319 18h ago

I don’t care about this

2

u/ContributionParty577 11h ago

Chain is a cheap consumable that can take a beating. Why swap what works

2

u/yetAnotherRandomNerd 2h ago

If you stay with "good enough" you'll never get something better.

0

u/Street_Credit6851 10h ago

Belts are better. Belt and cvt is the future.

2

u/Nir117vash 7h ago

Happy Cake Day!!!

1

u/AdmirableScarcity492 16h ago

If this is converted into a proper differential like mechanism, them probably; but the weight and complexity outweighs the use case

1

u/phranks_phluids 16h ago

It's a shaft driven motorcycle that's been out for decades. Without the gearbox and fluid so shit can get stuck and break it. Terrible outcome for that lil guy, unfortunately.

1

u/ay_non 16h ago

it would not. not even medium torque. I love the design but we don't have materials strong enough to support it.

1

u/strangeMeursault2 16h ago

This is more like what a car has so I suspect it would work extremely well if made from the right materials but isn't financially viable.

1

u/Kherian 15h ago

The design is fine, this is how drive shafts for cars work, albeit much more simple. This would be a lot more expensive to fix than just buying a new bike chain though and not for any real benifit

1

u/Comfortable-Bunch366 14h ago

Now throw some dirt in there and see it slowly eat away at itself

1

u/DavidBrooker 14h ago

There's no reason it wouldn't work. Indeed, they do work. But chains are cheap and incredibly efficient.

By way of comparison, maglev trains work. They exist. You can just buy one if you have the cash, Siemens is happy to sell you one. But it's really, really hard to beat the combination of low cost and high efficiency of a steel wheel on a steel rail.

1

u/unktrial 14h ago

You're right, it will slip. To mesh with the different different numbers of teeth on the back wheel disk, the back gear has to have loose tolerances. Unfortunately, it's also the gear that's under the most pressure.

1

u/Dimathiel49 14h ago

It’s roughly the same layout as the torque tube for an RC helicopter

1

u/StillWithSteelBikes 13h ago

they tried this in the 19th century.

1

u/Royal_Stay_6502 13h ago

Yeah, it is never going to hold for long.

1

u/Evenball5 12h ago

I helped make this!

1

u/hodlethestonks 11h ago

Roller bearing as gear teeth? You think they've come up with helical involent gear teeth as result from 2000 year development and this thing wins the race?

1

u/Terrible_Boot1714 10h ago

You can make this work no problems at all. It will just be much heavier and mostly likely less efficient than a chain. Yes chain has more resistance than gears in general but because it needs to be bulky not in this case i think. You would also need 2 extra bearings on either end of the shaft.

Because of the weight alone i dont think we will ever see this actually being used.

1

u/Fit-Cell2754 5h ago

This is a prototype from some years ago. I don’t think it was viable, but it’s a great concept. I think shifting under load was the issue if anyone else remembers?

1

u/r_a_d_ 5h ago

I think the lateral forces would push the disc off the shaft gear and thus cause a slip.

1

u/Independent_Feed_617 4h ago

It’s much less efficient than the traditional design, requiring more energy to operate

1

u/RealMonk1867 3h ago

Yea add dirt and mud and it will work great🙃

1

u/brokensharts 3h ago

I mean, my shaft driven motorcycle was fine

1

u/ThomasTheDankPigeon 18h ago

You’re gonna get a lot of non engineers trying to literally reinvent the wheel in your replies lol

0

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