Bent chainstay
10-20-18, 11:54 AM
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Bent chainstay
After struggling and cursing at the BB cup to come it finally came loose. But inspecting the frame furthur I noticed the drive side chain stay is bent inward. Roughly 3 inches above the dropout is bent. Is there a quick fix for this. Luckily I dont see any cracks at any joints
Much thanks.
Much thanks.
10-20-18, 12:10 PM
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"Quick fix": bend it back? *Slowly* though. I've spread an old steel frame using the 2x4 and a chair method described by Sheldon Brown - maybe something similar could be done to put this back to where it should be?
https://www.sheldonbrown.com/frame-spacing.html
https://www.sheldonbrown.com/frame-spacing.html
10-20-18, 12:17 PM
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I had the same issue with my Valley Runner. I watched this:
It worked out well.
It worked out well.
10-20-18, 02:03 PM
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I would try to work on the chainstay as it's looking fine. However that seat stay is a bit bent. But even this isn't a big deal. The bend is rather slight and likely has no structural impact (bad pun). In fact bending it back only compounds and structural aspect, however slight. But is cosmetics is what you're after then go ahead and do straighten it with no worries except as to how you do it. Park made a tool just for this purpose, don't remember it's number. basically a beam with three hooks/claws along it's length. The two at the ends could slide along the beam to be positioned at each end of the stay's bend. Then the center one would pull the bend back as that claw was on a threaded shaft. This tool was a bit unwieldy but worked quite well with some focus and care. As the straightening force was a screw produced one the chance for a booboo was less then using wood blocks and a big hammer.
I've done enough of each type of stay straightening before and much prefer the Park tool. But a skilled guy can do wonders with crude tools where an inexperienced guy can ruin a bike with expensive tools. Andy
I've done enough of each type of stay straightening before and much prefer the Park tool. But a skilled guy can do wonders with crude tools where an inexperienced guy can ruin a bike with expensive tools. Andy
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10-20-18, 09:32 PM
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Use caution, go slow, common sense is good, it's easy to fix.
turned into this
turned into this
Last edited by peugeot mongrel; 10-20-18 at 09:55 PM.
10-20-18, 11:54 PM
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Thanks everyone for input. I did see that YouTube video earlier today.
i do have clamps so ill most likely try peugeot mongrels method.
Ill update with progress
i do have clamps so ill most likely try peugeot mongrels method.
Ill update with progress
10-21-18, 06:55 AM
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The Park Seat and Chainstay Straightener was the SS-1 and is discontinued. It's a great tool. My LBS has one. Straightened a bent chainstay in short order.
10-21-18, 09:46 AM
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The bend I see in your picture seems to be the seat stay, not the chain stay, yes? In any case, check alignment, so that you don't take a misaligned frame and further derange it when straightening the stay.
Make sure you use something to spread the force when you try to bend the stay. So, for example, take a little block of 2x2 (say 1.5 inches long. Drill a hole just about the same size as the stay. Saw the wood block so that you end up with two blocks, each with a a groove that fits the stay. Make two more of these (you need three). Use these to apply force was suggested above.
After straightening make sure that you ensure alignment, spacing, and dropout parallelism. Good luck!
Make sure you use something to spread the force when you try to bend the stay. So, for example, take a little block of 2x2 (say 1.5 inches long. Drill a hole just about the same size as the stay. Saw the wood block so that you end up with two blocks, each with a a groove that fits the stay. Make two more of these (you need three). Use these to apply force was suggested above.
After straightening make sure that you ensure alignment, spacing, and dropout parallelism. Good luck!
10-21-18, 10:09 AM
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note the the hole in the block for the chain hanger. Also contact points to the frame are at the bridge and dropout. It takes very little force so shoot for under then take the block off and look at it
10-21-18, 10:25 AM
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10-24-18, 09:49 PM
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Few days ago i was talking to my LBS owner and he needed a few bulbs and ballasts replaced in his shop. We made a deal that is do it for him and he fixes my frame seat stay. Id say it's an even trade since he did a great job on straightening it.
Before
After
Before
After
10-24-18, 09:57 PM
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And it wasn't that shop owner bumping into the frame in his dark shop that bent the stay was it? 
Andy
Andy
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