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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 01-08-10, 06:59 PM   #1
kroozer
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Can I straighten a leftist frame?

I have a 1971 Schwinn Super Sport that pulls quite strongly to the left, enough that it can only be ridden no-handed with great difficulty. The down tube/bottom bracket joint is offset to the left by about 5 millimeters, which is visually quite noticeable. Iíve never seen such an arrangement before, and Iím thinking this might be the cause.

Can I do anything to improve the handling, short of drastic measures like re-brazing the frame? This is not a bike Iím going invest a lot of money in. I am thinking along the lines of tweaking the rear stays or dropouts or something. Iím not looking for absolute perfection, but I would like to stabilize the ride a bit. I appreciate any suggestions.
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Old 01-09-10, 07:02 AM   #2
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you should be able to align that frame. I would do the traditional string check and also check the fork. 5mm is probably not going to cause a frame to pull noticeably, but it could be an indicator of the real problem.
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Old 02-05-10, 08:03 AM   #3
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Originally Posted by kroozer View Post
I have a 1971 Schwinn Super Sport that pulls quite strongly to the left, enough that it can only be ridden no-handed with great difficulty. The down tube/bottom bracket joint is offset to the left by about 5 millimeters, which is visually quite noticeable. I’ve never seen such an arrangement before, and I’m thinking this might be the cause.

Can I do anything to improve the handling, short of drastic measures like re-brazing the frame? This is not a bike I’m going invest a lot of money in. I am thinking along the lines of tweaking the rear stays or dropouts or something. I’m not looking for absolute perfection, but I would like to stabilize the ride a bit. I appreciate any suggestions.
I think you have to bend in the right wing.
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Old 02-05-10, 09:30 AM   #4
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Is there any way you can post a photo?

As I said in your C&V thread on this issue, I don't understand how the down tube could be offset by 5 millimeters since I watched these frames being built at the factory and they were tack brazed on opposite sides of each tube in jigs to ensure tight tolerances before being removed and the fillet brazing finished. I suppose it's possible both the tack welds on the down tube at the BB shell popped loose and the finish brazing was off, but it sure seems like that would haver been noticed by the brazer, the frame put back in the jig, and the tack brazes redone.

Here's the down tube/BB shell brazing on my 1973 Super Sport, and it's right on the money.

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Old 02-05-10, 11:51 AM   #5
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I would guess it was possible someone had a bad day and put the parts in the jig wrong.
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Old 02-05-10, 12:10 PM   #6
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I would guess it was possible someone had a bad day and put the parts in the jig wrong.
I suppose that's possible, but for brazers who built these frames day in and day out it sure seems improbable. I'd like to see a picture.
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Old 02-05-10, 04:28 PM   #7
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I've heard of BBs put in backwards on factory frames. Getting that much offset would require some kind of "spacer" getting in the Jig. Possibly a part that was too tight and didn't seat well?
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