Variable contact pressure on a friction drive?

[peterjd]

Since there are (or have been) friction drives marketed with automatically variable contact pressure (ie between drive roller and tyre) to mitigate slip eg in the wet, I am wondering if I can fit a simpler user controlled variable pressure 'trimmer' (the basic pressure against the tyre is spring controlled) on the 'cobbled together' friction drive which I have fitted to my old Bickerton folder? I am thinking of something adapted from a cable or hydraulic brake, so that I can temporarily apply additional contact pressure to the tyre when on a hill or on wet roads to reduce slip and increase traction. Any thoughts? Incidentally the converted Bickerton is quite fun in the dry and on flat or relatively low slopes - is relatively light and still foldable so goes easily in the car boot. Peter

 

[amberwolf]

I used a friction-type gearshifter (no detents) on the first friction drive I made way back on DayGlo Avenger. I'm not sure if there's still any pics of it on the DGA thread since so many old pics have been lost, but there might be on my old http://electricle.blogspot.com ebike blog from way back then.