Re: how much better is this?
Thanks for the links. There were a couple that I had missed and made for interesting reading. Nevertheless, as you discovered there wasn't, and to my knowledge never has been photographic evidence, or otherwise of a failure of the chain stay due to mounting a tensioner bracket with a screw or bolt.
Yes, I've not used the method on any of my later builds preferring instead to fabricate and weld a bracket that spans the seat and chain stay but I do have one bike, my first in fact that has roughy 1800 miles on it and I've never experienced any problem with the 3/16" hole that I drilled to bolt the tensioner in place. I've even gone so far, prompted by these discussions, to inspect the area, removed the bracket and examined the hole and surrounding metal and to date there is no evidence of stress fatigue or cracking.
And, yes, I'm a lightweight and I never abuse my bikes but I've hit a few bumps and at speed. I'll also admit that the bike in question is an older, 90s vintage, U.S built Roadmaster that might be a little heavier made than some of the currently available department store bikes. Especially the aluminum framed ones.
The biggest area of concern is obviously the down tube at the front engine mount area. Now...here's where we'll agree. I will never advocate drilling a frame to mount an engine. That's simply asking for trouble and most likely getting it, again, especially if the frame is alluminum (alloy). I've also seen holes drilled in the seat stay to mount brakes. I wouldn't do that.
I simply maintain that the tensioner bracket, if used, must be secured by some method additional to clamping, to keep it from eventually being pulled inward with the predictable results. If that means drilling a small hole in the chain stay and bolting the bracket in place, I'll stand behind my opinion that it does not compromise the frame integrity.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"
Last edited by 2door; 12-17-2010 at 01:32 PM.