Plainsman

Hi all, I’m about to sell a nice Cycleops Spin Bike, and I was concerned about the cranks which were getting a bit of surface rust on them. I soaked them in rust remover, which knocked out the rust, but also some of the paint. I want to hit them with a fresh coat from a rattle can, but what is the best way to protect the threads when painting? (I will only paint the crank arm on the drive side - the ring will get masked off. TIA!

guy153

I usually just try to stuff a bit of tissue paper in to catch most of it and then clean any paint out with acetone afterwards.

You can also make a crude thread chaser by cutting a couple of longitudinal slots in a bolt the right size. That will clean out any last bits of paint.

dsaul

Just roll up a small piece of paper, insert it into the hole and let it unroll to fit the hole. I do the same with head tubes and bottom brackets when I paint a frame.

Plainsman

what do the longitudinal slots do? Am I right that Crank bolts are M8 with a fine (1.0mm) pitch? 9/16” for pedals with 20 threads per inch?

guy153

The slots give the paint, dried up grease, threadlock and any other junk that may be in there somewhere to go. If you just thread a plain bolt into a dirty thread it gets stuck and may well damage the thread if you persist.

A proper tap also has large slots. These are for actual metal chips, but a tap can also be used just to clean up a thread if you have one the right size.

Not sure what the sizes are of crank and pedal threads. I think the crank bolt usually needs a 14mm socket and 13mm is usually what goes with M8.