In the name of science let me reconstruct what happened more clearly…
I rode backward (awkwardly holding a railing) for a few hundred feet. When I turned around and rode forward I didn’t notice any problem with the pedals for about 50 yards when I stopped and found that the pedals had unscrewed and begun to strip. I tightened the pedals the best I could with my fingers and rode home (forward, half mile+). Of course riding home didn’t help but the damage was done and knew I’d be getting parts.
Here is my theory…Precession relieved the tension and riding forward with gravely bearings was enough to unscrew them at that point… Would anybody buy that conclusion?
If I can’t include the bearings in the problem it will be hard to justify new pedals to the household budget committee. (just kidding)
There has been a good amount of interest in the thread and so far no one has come out and said that this has ever happened to them. Was this a fluke?
For practical purposes I think all the answers came early. The scientific adventure has been fun though.
The threads on the pedals are usually fine. It’s the threads in the cranks that almost always take the beating. So you’re probably looking at new cranks, but your pedals don’t sound that great either. I’d go the whole nine yards: Cranks, pedals, pedal wrench.
That is correct. The steel pedal spindle stripped out the aluminum in the crank arm without suffering damage itself. New cranks have been ordered. Gotta pick some pedals (any favorites out there?). I have a wrench (one less thing).
Well, I run a juggling /unicycling club, and we have several times had pedals come loose, and once or twice strip. It has usually happened when , after adjusting the seat, the kids re-tighten it, but facing backwards. Effectively they are then riding backwards wrt the pedals. They are just applying torque in the same direction as you would to unscrew the pedals. Friction and the slight slopping about of an imperfect screw does the rest. I think the best you can do, other than Loctite. is to make sure the pedals are screwed in properly tightened. Or redesign the system, which was not really prescribed for riding backwards.
John F: I would agree that the term precession could be used in conjunction with using a diablo.
Is this a great forum or what? A new rider comes along, asks a simple question about his pedals coming unscrewed and the thread evolves into a discussion about precession, spindles, bearings, gyroscopes, frictional forces and righty-tighty.
(just kidding)
What a brainy bunch 'o folks.