I work on some rental bikes that feature the the shimano nexus-3 with rollers brakes (specs here). Last year we had a handful come back with a seized/locked up hub, loose axle nuts and/or loose cone nuts, and the anti-rotation washer had ground out the threads on the axle (it was not preventing rotation). I cannot figure out what is causing this problem, though I initially assumed it was poor mechanics because on the majority of the initial bikes that came back a prior repair requiring the removal of the rear wheel had been done-- by an inexperienced mechanic. However, 7 bikes that have never had their rear wheels removed/worked on have just come back, and I'm really at a loss about what to do to prevent this issue in the future-- I can replace the wheel/hub, but it seems foolish to do so without understanding the cause of this problem.
Does anyone have more experience with these particular hubs/insight into how or why they are rotating when they ought not to be?
Post by lancetigerblood on May 19, 2019 20:26:33 GMT -6
I would double check all the bearing adjustments of your rentals on a regular basis. Cones and axle nuts done to up to the torque specified, and fresh roller brake grease would help for sure. I used a check in sheet for rentals that mechanics use to check each part on a bike to see if any service of damage needs to be taken care of.