The photo was from a site that no longer seems to be up. The pedal on the right, measuring at 15.7mm is the same size that the pedal on my indoor spin bike uses and I want to use standard 9/16 threaded pedals instead.
Has anyone come across this size??? Do adapters exist to step up standard 9/16 to 15.7mm?
The pedal on the right seems to have some sort of adapter on it? If you can't find anything bike specific you can get general purpose coils (helicoil i think? ) for for bolting stuff in oversized threads , no idea if that will hold up probably not great if you need to remove them often.
I didn't know if that might work, but thanks for the suggestion. I don't plan to really take the next set of pedals off, unless for servicing, so this might be an option. Never used them before, but know of them.
I think the right pedal has a Unior thread adapter on it. These are used to repair a stripped crank arm. When the 9/16"x20 threads strip out you ream the hole and re-tap it with a 5/8"x24 thread, then and use the adapter to make the pedals fit.
https://uniorusa.com/products/pedal-thread-inserts-10-pieces-set-right-58x24
https://uniorusa.com/products/crank-saver
What this guy said