Old mechanic told me to stop greasing pedal threads, glad I listened

I was rebuilding a set of Shimano platform pedals last week, the kind with the little loose ball bearings inside. I've always put a thin layer of marine grease on the threads before threading them into the crank arm, you know, to prevent seizing. But this old timer at the co-op, guy named Jerry who's been fixing bikes since the 70s, he told me to stop doing that. He said grease on the threads actually creates a false torque reading, so you think it's tight but it's not, and the pedal can back out on a ride. I figured what the hell, I'll try it on my commuter bike. So I cleaned both crank arms with some isopropyl alcohol, threaded the pedals in dry, and torqued them to 35 Nm exactly. It's been about 300 miles now and no issues at all, they're still rock solid. Has anyone else had a pedal come loose from using grease on the threads?

2 comments

2 Comments

webb.xena3d agoMost Upvoted

Hold up, your buddy actually had a pedal fall off while riding downhill? That's terrifying... I can't believe grease could cause that much trouble.

ben_shah933d ago

Yeah so Jerry is 100% right about this one. My buddy had his pedal fall off going down a hill because he greased the threads and it backed out over time. The dry torque reading is way more accurate, especially with aluminum cranks. I still use a tiny bit of anti-seize on steel parts, but for pedal threads I go dry now too.