Originally published at: https://boingboing.net/2018/07/23/watch-how-this-chain-free-bike.html
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Haven’t shaft-drived bikes exited for a few decades? Actually, looking at Wikipedia, it looks like they’ve existed since the 19th century, but in any case there are still modern versions being built. I remember a biking magazine about 15 years ago hyping these up as the next big thing.
What looks most innovative here is the rear cassette, and the shifting mechanism. I guess you can always put a new spin on old technology.
Although, I feel like the benefits are usually posed in terms of fewer moving parts, and less chance of dirt and grime affecting the drive train. Won’t dirt and grime affect those spinning bearings in exactly the same way?
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Yeah, it seems weird to make a shaft driven bike that doesn’t use an internal hub.
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Indeed, there’s a lot of shaft driven bikes out there. Most others claiming that shaft driven bikes have been around for ~100 years.
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This one is a prototype made by a company that markets low-friction bearings and lube. The goal was to demonstrate a concept that improved efficiency. The existing shaft drive bikes are less efficient than a chain/derailleur bike, even without the draggy gearbox. But this bike is really only a demonstration of a possible geometry. There is almost certainly no way that a rideable version could be produced that wasn’t far too heavy.
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Yeah it should really be mentioned here that this is not a working bike. They don’t have a way to shift yet - what they showed there was a mockup of how it might work. I expect there will be severe problems with this design in practice.
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some electronic manufacturers call this direct drive
Sure, shaft drives aren’t new, but a shaft driving a thin, complex gear plate with rotating contact bearings instead of the usual teeth is.
I can see that they’ve gone down a bit of a rabbit hole with the bluetooth controlled variable length electronic shaft. I would have used a magnetically or mechanically controlled sliding shaft of fixed length, personally - but it’s easy for me to criticise after somebody else came up with the breakthrough!
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I think their concept is cool. My concern is how good is the bluetooth signal/lag? I don’t use bluetooth a whole ton but i’ve never had a totally flawless experience with it and for casual riding this might be ok but high stakes competition any lag or glitches might cause huge issues. As you said, i think a non-wireless solution might be better. Beyond that i think there’s promise to the concept if they are able to make everything durable and robust
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Well, this is never going to work. You could clearly see in the video, when gear teeth were spinning, half of them were going forwards and the other half were going backwards!
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Bluetooth probably won’t even work if you are next to a car with elderly ignition wiring, or a truck using a CB radio.
I like the way you could fit 50 different gear ratios on it fairly trivially.
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Simplest method for that design might be to preload the shaft one direction with a spring, and pull it the other with a ratcheting cable like existing indexed shifters.
I think chain still wins out in terms of cost, durability and reliability. A belt drive and an internally geared hub might be the future winner but again that depends on cost and durability- affordable IGHs currently just can’t cope with the abuse of regular mountain biking, while something like a Rohloff hub which could cost as much as a decent bike by itself.
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Looks like it could work in cost no object racing bikes if they got the weight down, but for everyday use I can’t wait to get a belt drive bike.
Wireless electronic shifting is a thing now and it works great. I don’t think it uses bluetooth, probably some proprietary wireless protocol
My biggest concerns about this design is how it actually performs under load, especially how well shifting works under load. All their demo videos have a free spinning rear wheel, they’re probably only putting 10 watts into it. It’s very common for someone my size to put 400 or 500 watts into a steep climb, probably with some shifts needed during the climb. A sprinter my size will easily put out 1500+ watts on a sprint.
I’m also concerned about what happens if something gets jammed into the mechanism - a pebble or twig or what have you. That happens a bit with chains too but it’s not too bad.
I think their 99% efficiency claim is probably baloney and I don’t think I’d believe it without some rigorous testing.
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Belt drives do seem pretty sweet. I rode a tandem that used one.
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Yeah this seemed like a bunch of BS even with pristine conditions. 99% efficiency under what criteria? No data on this bold claim beyond just PR, sure i’ll believe it.
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I’m looking at wear. Steel against aluminum? Is there a lube layer? Will black aluminum dust (w/ lube) be constantly flung outwards? If one set of teeth wear overmuch or one tooth breaks I only see replacing the entire cassette/disc.
If one switches to steel for the plate it will be difficult to machine and heavy. Even in Al this looks time consuming.
I love shaft drives on motorcycles for the low maintenance but keeping them safely contained and lubed is the other part of their selling point. Those tooth edges will self sharpen quick af (if they aren’t already).
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It’s clearly fake. The bike doesn’t even have pedals. How’s that supposed to work?
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My theory is that they didn’t put pedals on because if they did eventually someone would insist to ride it
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My workplace has shaft-drive yellow bikes for anyone to use. I rode them a couple of times a few years ago and thought that they needed more torque than a chain-drive.
Well, I guess in the technical sense, the chain itself wouldn’t have any torque at all, but hopefully y’all knew what I meant
