Friction Drive comes of age

[Recy]

This will not be for everyone, but there's a very interesting thread by Kepler on ES - he has developed and produced a mounting hardware for Friction Drive bikes that's now ready for prime time. Particularly intriguing is that there seems to be a timely coming together of very efficient outrider rc motors, digital & analogue controllers and even skateboard motor developments that make a relatively powerful and very reliable Friction Drive bike both cost effective and pretty straightforward for an enthusiast to put together. A very light weight and relatively inexpensive system that seems to require a nice light weight road bike, Kepler gets anything up to 80km a charge from his set up at a good rate of knots and has done something like 5000km in total developing it.
As I say, not for everyone but certainly a great way forward for some.

Thread on ES:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=84905

 

[the_killjoy]

It still doesn't solve any of the old problems of slippage in the wet and tyre wear in the dry.

 

[Recy]

He states in the thread that it's not for wet conditions (he's developed it in Australia) but his method does not seem to produce any excess tyre wear. He's not using any special friction coating on the motor, it relies on an uplift mechanism on to the tyre provided by his mounting hardware. And it just works.
Quite a read but well worth the trouble for those interested and it explains it all better than I can.

 

[anotherkiwi]

It still doesn't solve any of the old problems of slippage in the wet and tyre wear in the dry.

Not to mention slippage in the dry and tyre wear in the wet...

(ex velosolex rider experience)

EDIT: Reading through the thread it doesn't seem that many posting lived in France in the 70's...

 

[flecc]

Indeed. My experience is long enough to have taken in all the various forms of friction drive, and they are not a viable method for e-bikes. But like so many dud out of date ideas, it keeps returning.
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[Recy]

Kepler has been a substantial long-term contributer to e-bike knowledge for quite a number of years - he's no light-weight in the field. Amongst other topics he is one of the 'go to' sources for Bafang controller programming and his settings & insights have become pretty much definitive.
It was great fun to read through his friction drive thread and it's certainly little to do with the woes people here have spoken of. Its combination of cutting-edge technology, both digital and analogue hardware, genius and generous thinking from contributors and Keplers ability to test & weave it all together into what has been a long term side project for him is simply fascinating and an uplifting example of grass roots development from keen minds & skilfull hands. And along with all that.... it just works. And relatively cheaply too.
As I say, not for everybody but terrific for those that fit the idea. and at the very least an uplifting read.

 

[Danidl]

Kepler has been a substantial long-term contributer to e-bike knowledge for quite a number of years - he's no light-weight in the field. Amongst other topics he is one of the 'go to' sources for Bafang controller programming and his settings & insights have become pretty much definitive.
It was great fun to read through his friction drive thread and it's certainly little to do with the woes people here have spoken of. Its combination of cutting-edge technology, both digital and analogue hardware, genius and generous thinking from contributors and Keplers ability to test & weave it all together into what has been a long term side project for him is simply fascinating and an uplifting example of grass roots development from keen minds & skilfull hands. And along with all that.... it just works. And relatively cheaply too.
As I say, not for everybody but terrific for those that fit the idea. and at the very least an uplifting read.

One can admire and respect the engineering and design effort involved while being critical of the fundamental science driving it. I look at the current revival of vinyl records and the engineering effort involved in trying to get over the fundamental limitations of that medium in the same light.

Looking at the size of the motor he has engineered I ask myself why he could not mount it with a cog wheel , place it on the rear frame and drive the chain.
His masterpiece is the size of the motor and weight reduction

 

[flecc]

Kepler has been a substantial long-term contributer to e-bike knowledge for quite a number of years - he's no light-weight in the field.

My knowledge of friction drive bike motors spans 66 years, both petrol and electric in many forms, and with a wide variety of roller surfaces and profiles to obtain adequate grip.

The roller drives all fail in various ways according to conditions. That's why they all vanished from the market, in many cases finishing the companies promoting them.
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[anotherkiwi]

We aren't criticizing his engineering or talent just the principle of rubbing even more rubber off a tyre than the road does in order to move forward. It works, I have ridden 100's of kilometres on a VeloSolex but it isn't efficient, in fuel consumption or in power delivered. On the VeloSolex riding in the rain was downright dangerous, one hand on the handlebars and one hand on the motor lever forcing it down onto the tyre as hard as one could.

There is one place a cheap light friction drive would interest me: as a reverse gear on a vélomobile or trike.

 

[flecc]

We aren't criticizing his engineering or talent just the principle of rubbing even more rubber off a tyre than the road does in order to move forward.

This one below was an interesting French variant on friction drive which avoided using the tyre. It had a pair of motors with rollers that pressed onto rubber tracks each side of the special rim.

A cunning point was that it automatically released the motors away from the rim sides as it reached the legal 25 kph assist limit:

 

[Danidl]

This one below was an interesting French variant on friction drive which avoided using the tyre. It had a pair of motors with rollers that pressed onto rubber tracks each side of the special rim.

A cunning point was that it automatically released the motors away from the rim sides as it reached the legal 25 kph assist limit:

...... Damn I thought about using special rims when I was writing my previous post. Now is that two motors or one and will that be illegal under the EPAC rule? ( Just being arguementive and reprising a previous set of postings)

 

[the_killjoy]

Like a giant old fashioned dynamo in reverse, mind you they rarely gave much competition to a glow worm.

 

[flecc]

...... Damn I thought about using special rims when I was writing my previous post. Now is that two motors or one and will that be illegal under the EPAC rule? ( Just being arguementive and reprising a previous set of postings)

Should be legal since the crucial point is the stated motor power. There is precedent too, the SRAM Sparc hub motor contained two motors and was sold throughout Europe including the UK, Halfords the last outlet.

Since these two motor solutions have a common controller, it's arguable that they are only one motor, on the basis that without a controller a brushless motor is incomplete, cannot operate so cannot be considered to be a motor. Basically these are single motors with more moving parts than usual.

Importantly, neither the type approval exemption nor the EAPC regulations rule out more than one motor used within the power limit.
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[flecc]

Like a giant old fashioned dynamo in reverse, mind you they rarely gave much competition to a glow worm.

Much more powerful it seems. The Cybien motors were bought from the USA by the French maker, but I don't know who made them or what their original application was. It certainly wasn't e-bikes.
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[Recy]

Old (but good) ideas that don't quite work frequently become excellent when re-invented/revisited with new tech and the new thinking it can inspire. Thank goodness!
I think we've all had ideas before now that we've had to shelve because affordable or available technology was not around.
This iteration of the friction drive concept might be coming into its time for this reason, notwithstanding previous experience. Certainly worth reading the thread if you care to and within it is all the reasoning too - for example the use of friction applied to the tyre for drive instead of the seemingly better idea of cog-drive. Incidentally, in terms of tyre wear Keplers test bike has over 5000km of use without anything excessive it seems.
Again, the thread explains far better than I. Amongst other things I really like the light & stealthy look & methods applied.

 

[flecc]

Certainly worth reading the thread if you care to and within it is all the reasoning too - for example the use of friction applied to the tyre for drive instead of the seemingly better idea of cog-drive. Incidentally, in terms of tyre wear Keplers test bike has over 5000km of use without anything excessive it seems.

Not only have his methods and roller surface been used before, we've had two near identical iterations of this design in the last few years. They've both vanished, as his will.

Friction drive onto exposed rubber is a defective method and no amount of repetition of previously tried methods is going to change that. No-one wants an e-bike that only works part time, it's said Kepler's doesn't work in the wet, need I say more?

Only in fantasy theory could a method be created to make this type of friction drive work usefully. In practice if it doesn't slip under any conditions, it will be victim of a considerable efficiency loss, akin to that mentioned by Another Kiwi above.
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[anotherkiwi]

Old (but good) ideas that don't quite work frequently become excellent when re-invented/revisited with new tech and the new thinking it can inspire. Thank goodness!
I think we've all had ideas before now that we've had to shelve because affordable or available technology was not around.
This iteration of the friction drive concept might be coming into its time for this reason, notwithstanding previous experience. Certainly worth reading the thread if you care to and within it is all the reasoning too - for example the use of friction applied to the tyre for drive instead of the seemingly better idea of cog-drive. Incidentally, in terms of tyre wear Keplers test bike has over 5000km of use without anything excessive it seems.
Again, the thread explains far better than I. Amongst other things I really like the light & stealthy look & methods applied.

I know he is from Australia and that it doesn't rain often in some parts; in Melbourne for several years according to my sister who lives there. Friction drives don't work well in the wet. If they were a good idea they wouldn't have disappeared from the market and the companies that had invested in them wouldn't have gone bust.

In my previous post I said that I too would like to see one of these put to a specific use. All technologies have a niche. And again I stress this is very cool engineering well executed, no one is criticizing the work he has done. But it won't work here, on any bike I might own, for getting me from point A to point B. It rains cats and dogs and there is no way it will climb 15% gradients in these conditions despite all of Keplers efforts. He can't bend the rules of physics too far: to have traction you need grip and grip has a side effect - wear. Even steel cassettes wear out eventually and they are just slightly stronger than rubber (synthetic or otherwise). </tongue in cheek>

 

[Recy]

Whatever the relative shortcomings or otherwise of geography, precipitation, physics or (even) 'fantasy theory' it certainly is working for those folk on that thread - that is what I was drawing attention to (from the very first line of the main body) by starting this one.
Thing is, he's Kepler - we're not.
He's making it work for him and others who are actively involved over there. No one over here who's commented so far did.
Here and then vs there and now.
Sounds like local evolution to me.
And after all - hey! It's only an intesting thread about pedal bikes and little electric motors.
But still, more power to him and those who make things work & happen - for fun.

 

[flecc]

But still, more power to him and those whe make thing work & happen - for fun.

Yes, fully agree with that, just sounding the warning of the very real limitations, due to the physics involved. They are the same for Kepler in Australia as for us here in Europe.

I don't know what it is about bikes and e-bikes that makes so many want to keep reinventing failed past ideas, seemingly out of lack of knowledge of what has already been done leading them to do exactly the same, as in this case.

I'm betting Kepler's effort will vanish without trace.
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[Recy]

Not to him though...