Originally Posted by
Milton Keynes
I've mentioned before that when I bought my first mountain bike back a little over 25 years ago, I noticed at the store an aftermarket automatic shifter that you could bolt onto just about any multigear bike. Somehow it would automatically shift the rear derailleur as needed to provide even gearing. No, I did not buy it because it looked awful cumbersome and I didn't really see any advantage over manual shifting. Plus I like being in control of when the gears shift.
And no, I don't have any idea how the mechanism worked. It's been too long and I didn't look that closely at it.
There's a LandRider auto shift, it needs though a plastic v-belt disc to control a v-belt behind the freewheel. Interesting derailleur though, no other wires needed for shifting. Shifts when pedaling harder, troubles might come when on smallest cog and you have to maintain certain speed:
LandRider Auto Shift derailleur
And Bikemanforu has done at least two videos about this thing to the Youtube...