Bicycle Mechanics - Uh-Oh, bent chainstay...
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02-14-10, 11:57 PM
So i finally got around to throwing some disk breaks on my SS, when much to my chagrin i discovered my disk-side chain stay has a dent that appears to have changed its dimensions just enough to (maybe, just maybe) interfere with the disk. What can i do? My frame is chromoly, is there any chance i could have it bent back?
02-15-10, 01:05 AM
aaallllllright, that was a little more work than it should have been but here's some evidence...
& I apologize for how difficult it is to see, but flashes and dirty, glossy black paint don't mix.
...my disk-side chain stay has a dent that appears to have changed its dimensions just enough to (maybe, just maybe) interfere with the disk. What can i do? My frame is chromoly, is there any chance i could have it bent back?
Well, Cr-Mo can be immensely forgiving, and undoubtely there are frames more messed up than that that keeps on delivering good service.
And WRT to brake rotor clearance(if it is an issue) it shouldn't be too much of a problem bending it back. Getting it all in alignment can be another issue though.
But if it was me I'd worry about the seemingly very sharp crease at the bottom of the dent.
I can't think of any way to get that one out. Either it'll act as a stress riser for later fatigue failure, or it'll act like scribe mark for the chain stay to fold right there next time the bike sees some rough handling.
02-15-10, 02:27 AM
My own thoughts are that while it may not have been an issue when the bike was stopped with rim brakes that when relying on disc brakes that will put more stress into both the seat and chain stays on that side that the forces acting on this kink will have more effect on the damaged area. By all means straighten it out. But at the same time keep a frequent and close eye on that damaged area for stress cracks or further deformation caused by that damage.
02-15-10, 10:33 AM
Straighten it. Be aware that there is now a stress riser and that it will eventually break. Being steel there will be ample warning so you will just need to keep an eye on it.
02-15-10, 10:01 PM
yeah... thats kind of what i was afraid of. dropped it off @ the LBS a few hours ago to see if they could help me out, i'll find out tomorrow. but thanks for the help.
02-15-10, 11:14 PM
They'll almost certainly tell you that it is toast, dead meat on a stick, bereft of life, gone to meet its maker, it is an ex-frame. Liability will suggest that and common sense about that amount of damage will support it.
I'd say it's time to start shopping for a new frame. I know that rear end failures are not as epic as front end ones but I would not trust that frame to haul my butt around the block anymore let alone across town or down some trail in the middle of nowhere.
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