Crank arm jumping during pedaling my EVO

I wonder if anybody else has experienced this: while pedaling the crank arm jumps forward, maybe once or like yesterday four times one after another. Quite nasty experience though happening rarely, all suddenly but makes me worried - what’s wrong? This last occasion happened while riding slightly downward sloping way thus no much force on pedaling required. Unfortunately didn’t make mental note on which gear I was riding, likely not on the light gear anyway.

Easy or difficult case to solve and repair? Thanks.


Not related but I want to tell you how much I enjoy your Strida pics. You are a blessed photographer! ☆☆☆

I hope somebody has an idea what’s going on with the crank arm.

Dear Marsal,

seems that this is a drive issue; your dealer should exchange it.
As far as I know they’ll be sent back to the factory for repairing.

Also should your dealer be able to mount/unmount the beltwheels of the drives if necessary.
There is a special “hook nut” and an electric (or pneumatic) impact wrench required.

Sorry to read that…

Good luck,


Chris, is the drive the bottom bracket?

If so, can this “crank arm jumping” problem happen to every Strida’s bottom bracket? Or just to EVOs? (Maybe I didn’t quite get your explanation. :slight_smile:

No dear Lady :smiley:

There can be a drive (gear drive, that means different speeds) inside of the bottom bracket.
Depending on bottom bracket diameter you can separate these;
inside of the 95 mm bottom bracket you will find only EVO drives (exact name is Sturmey Archer KS3) - the gears are available via backwards pedaling for ~ 120° in this case.

Inside of the smaller (and standard) 60 mm bottom bracket you can install different drives
(but not that of the EVO);

  1. The Schlumpf or ATS two speed drives - shifted by a heel kick sideways.
  2. Soon the efneo 3 speed drive - it has cable shifting.

No, not at all, don’t worry - that has nothing to do with single speed brackets :wink:

*notes Schlumpf/ATS two speed drives in her black booklet *