Mr Evil wrote:Foghat wrote:...Rack mounts feature M6 threads, which seem far more appropriate than M5 - why don't all rack-capable frame designers specify this?..
M5 bolts are stronger than you might think. Strong enough to carry the weight of anything you might reasonably put on the back of a bike.
I think they are up to the job so long as the weight of the rack is on the portion of the bolt that is right next to the dropout. It is when you introduce spacers and have the weight further out from the dropout that you risk things going wrong.
My Club Tour was an early one with M5s and I never had a bolt failure there.