Originally Posted by
MikeX
If it were my pedals and nuts, I’d
1) Polish the pedal shafts in the area where the fractures are occurring to a 600 grit or better finish to minimize the stress risers and make subsequent inspections easier. Various abrasive papers and cloths make that reasonable even if you have to use them “shoe shine” method. Better if you can run the final polish marks parallel to the spindle rather than circumferential.
2) I’d tear down the pedals every few hundred to a thousand hours of riding (if you ride a couple plus hours a day that’s about once a year) and seriously eye ball the suspect area for cracks. Dye penetrant or magnetic particle inspection would be a bonus but is probably overkill if you’re diligent about looking for cracking. Less so after the first couple of thousand hours. There is a “fatigue limit” for steel parts. Barring impacts, steel parts (does not apply to aluminum ect.) subjected to ten to the seven cycles (10 million cycles) without failure are unlikely to ever fail. 1000 hours of cycling at 100 rpm equals 6 million cycles.
Thirty years after the last Lyotard 460D was manufactured we're finally seeing fatigue failures. I am sure nobody who made those pedals ever foresaw a 30+ year service life.
In the days before clip-in MTB pedals (SPD, Crank Brothers, Look, & Time), Lyotard 460Ds were the favored pedal for professional cyclocross. They were rugged, smooth turning, and wide enough for quick entry and exit with muddy shoes. One standard setup then was football boots with all but the toe cleats removed, fitted with slotted cycling cleats, and doubled steel toeclips (to prevent squashing) bolted to Lyotard 460Ds. The straps were tightened only before the final sprint.