Originally Posted by
veganbikes
I would get new chainrings or cranks for an authorized Shimano dealer. Random cheap stuff from unknown unauthorized third party sellers is not really a good way to go. I would make sure to match old arm length unless you have a fitter telling you otherwise.
Yes, I am not convinced what you buy online is not always the same as the shops. I just checked my arm and it has the size stamped on it 172.5. Thanks