Are seatstay and chainstay bridges with mudguard mounts all M5 size? I could take the mudguards off my tourer to check, but that would mean taking the mudguards off my tourer.
Yes normally. Some frames have an m5 boss for mudguards and an m6 boss for a pannier rack but that's unusual. Sometimes the hole at the BB/chainstay bridge is unthreaded and you need a bolt.
Are seatstay and chainstay bridges with mudguard mounts all M5 size? I could take the mudguards off my tourer to check, but that would mean taking the mudguards off my tourer.