bsyptak

I have read the forums and Sheldon Brown's tutorial on cold setting a steel frame. My only concern is specific to my 1991 GT Avalanche MTB frame. I'll do the test to insure that my frame is bent, but when my wheel is sitting loose upside down in the dropouts, I only have about 1/8" of clearance on one side where the tire is closest to the chainstay and about 3/8-1/2" on the chainstay side. It's not causing any real problems (though mud undoubtedly will), but when the rear brake engages, it definitely tries to clamp down on a centered rim, sending the rim to where center should be. You can easily see the rim move toward center. I think this might be not so good. I don't think there is a way to uncenter the brake, and I'd like to fix the problem anyway, not live with it.

It seems pretty easy and straightforward to cold set/straighten a frame, but my concern is how the GT was welded. The seat stay tubes are welded to the top tube about 4-5 inches in front of the seat tube. ALSO, and most importantly, the seat stay bridge or brake bridge, whatever it is called, is welded to the seat tube. I think this is where the problem might lie. I think that by cold setting, I could cause this weld of the seat stay/brake bridge to break.

I'd like to keep the bike. It's got new wheels, newer fork and lots of maintenance parts over the years and is in generally fine condition. Plus, it's STEEL. But the bend is buggin!

Any thoughts on whether I'll break the frame?

bsyptak

I don't have an exact picture of my bike, but this ALU GT gives you the idea of where the bridge would be welded to the seat tube?

https://www.bonthronebikes.co.uk/prod...rer=GT%20Bikes

Retro Grouch 

How do you know that the problem lies in the frame and not in the wheel?

To test the wheel, flip it around in the dropouts. If the closeness moves to the other side, you probably just need to get your rear wheel redished.

To test the frame, run a straight edge from the head tube to exactly the same point on each rear dropout. Measure the distance from the straight edge to the seat tube on each side. If the measurements aren't the same, your frame is tweaked.

bsyptak

I'll check wheel and frame for the culprit this weekend, but the wheel only has about 100 miles on it.

Retro Grouch 

Hmmm. I think that's all the more reason to suspect the wheel. Lots of factory built wheels come with the dish all goofy.

rmfnla

Makes sense to check everything before you start bending your frame...

bsyptak

I would have done the string test for frame straightness as Sheldon says! I hope it's the wheel.

operator

I would do the wheel test first. Not the frame test.

halfbiked

If the brakes can move the wheel 'towards center would be' I'd look at the bearings. Sounds like way too much slop somewhere - the brakes should adjust to the wheel, wherever it is. They should not move the wheel at all.

Retro Grouch 

Yup, me too. It's easier to do and it's more likely to be the problem.