Little Friction Drive

[martx007]

As I haven't contributed anything for a long while, thought i would now weather is slowly getting better. And as I don't currently commute to work like the hardcore commuter that I used to be, I can play around a bit
Where I live now is as flat as a pancake so I have been messing with friction drives as a setup for my bike, as it has nexus igh and bottom bracket looks to complicated to entertain the idea of mid drive.
Mainly want assistance to not be overtaken as rapidly as normal by twenty somethings on my bike path route.
This is what I have done so far whilst waiting for the batteries to arrive(2 3000mah turnigys). I have tested with an old battery and it went well enough for gentle assist(which is what I want).
I am going to put an empty light on top of the front support to hide the motor a little (should look like a dynamo) and inside it will go the connections and the esc.
I thought about Q100h in a front wheel but would look too obvious so will try this for now
Any input welcome.
Martin

 

[dwvl]

Thanks for sharing this with us - it's always interesting to see something out-of-the ordinary . For your "gentle assist" use-case this looks to be a very neat minimalist solution. The gearing inherent in such a design plays to the strengths of a compact high-speed motor like that.

I imagine you're looking for about 150W of mechanical power output? I expect there will be quite high losses due to the roller having to push sufficiently hard on the tyre to get traction. Will you have the capability to measure electrical power consumption, so that we can get an idea of an efficiency figure?

A couple of things worry me a bit. One is the drag of the system when no power assist is required - it could be a bit like riding with the brake lightly applied? The other is its performance in the wet, in respect of the roller getting a grip on the wet tyre, and also in respect of the difficulty fitting a mud guard...

Please do let us know how you get on!

 

[sjpt]

Another issue is wear on the tyre. I hope that's not too bad. Good luck with it anyway

 

[Nealh]

The FD I have wears the rear tyre out in no time and works very well in the rain.

 

[RobF]

I suspect you will continue to suffer from tyre wear.