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Rear dropouts too wide now

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Rear dropouts too wide now

Old 12-23-14, 01:18 PM
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corwin1968
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Rear dropouts too wide now (NEW INFO)

I picked up a 1983 MTB and had the chainstays cold set, by a frame builder, to 135mm. I rode the bike for awhile and now the dropouts are widened to 140+ mm.

What might have caused this?

Generally speaking, can it be corrected so that the frame is safe to ride?

The frame builder who set the stays is about an hour away and I want to get some objective opinions before I take it back to them. Might they have done something wrong that caused the widening?

Last edited by corwin1968; 01-02-15 at 08:42 PM.
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Old 12-23-14, 01:25 PM
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The spacing shouldn't change. My first thought is a crack starting in the chainstay. Look closely at the chainstays behind the bottom bracket, especially on the inside and right behind the gusset in front of the tire. Right side is the most likely to fail first. If this frame is welded, the weld itself or right behind it is a good place for a crack to start.

Ben
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Old 12-23-14, 01:41 PM
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corwin1968
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There are no obvious cracks behind the bottom bracket or around the brace between the chainstays. I did take a couple of pics earlier and the right dropout itself appears to angle more inward than the left. It's visible in these images but it's even more apparent when viewing the frame in front of you.

I am a large rider (400 lbs) but I've never even so much as ridden off a curb on this bike and I've never had problems with other bikes I've ridden.

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Old 12-23-14, 01:54 PM
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Six jours
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How did you find the spacing was off? When you first put the 135 wheel in, did it fit properly? When you took the wheel out, did the frame spring apart? And now the same wheel won't go back in again?
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Old 12-23-14, 02:02 PM
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corwin1968
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Originally Posted by Six jours View Post
How did you find the spacing was off? When you first put the 135 wheel in, did it fit properly? When you took the wheel out, did the frame spring apart? And now the same wheel won't go back in again?
When I picked up the frame from the LBS, they had a tag on the dropout stating it was set at something like 134.4mm. I took the frame home and mounted a 135mm wheel but didn't really pay attention to how it fit but I did not notice anything unusual. Over several months I took the wheels on and off several times and at one point I noticed that I had to crank the QR a lot more than usual and that the axle didn't seem to be long enough. I rode it a bit but this bothered me so I took the wheel off and took the QR skewer out and it was warped (I suspect from being used to compress the stays to fit the axle). I measured the dropouts with a digital caliper and they came out 142.2mm.

Short answer is that based on my limited recollection, the 135mm wheel did fit correctly at first.
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Old 12-23-14, 02:16 PM
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In my opinion, if the frame was correctly spaced to 135 and now it actually measures 142 inside-to-inside, there is either structural damage somewhere, or your weight is actually causing the stays to spread. (No insult meant, just an observation on physics). It's unlikely that the fellow who did the coldsetting could have done anything to cause the problem, but it's always a good idea to check the brazing/welding around the seat and chainstay bridges after such work. On rare occasions the area can be damaged by the process, and perhaps even stressed but not broken, with visually apparent damage showing up down the road.

Regardless, in you shoes I would very carefully inspect the brazing/welding at the bottom bracket shell where the chainstays enter, the chainstay and seatstay bridges, and the dropouts. Even faint lines in the paint may indicate cracking and would need to be checked and possibly repaired. If absolutely no damage is found - and you're absolutely sure that the hub is 135 and the inside-to-inside dropout measurement is 142, I would simply squeeze the dropouts back together by hand and then pay extra attention to the spacing over the following months. If the problem recurs, the frame most likely just isn't strong enough for you and should be replaced before anything catastrophic happens while riding it.

Good luck!
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Old 12-23-14, 02:45 PM
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You can take advantage. if a 10x1 shimano freehub type axle

the added spacer on a Shimano Tandem axle ( they aim for 145), and adding the left spacer moves the hub to the right, = less dish

less Dish makes a stronger wheel, when trued up again, the rim is more centered between the Hub flanges...
at as stated 400 pounds you can use a strong rear wheel ..

maybe bump up to a 40 or 48 spoke wheel.

My Touring Load rig used a 48 hole wheel ..

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Old 12-23-14, 03:31 PM
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too much measuring...
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Old 12-24-14, 10:05 AM
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Makes more sense that the seatstays are being bulged out and widening the space when the wheel is removed.
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Old 01-02-15, 08:40 PM
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Last night I remembered something that might be relevant. While I was waiting for my Surly single-speed cog to arrive, I set up my Highlander as a single-speed using a 7-speed cassette and using the long dropouts to adjust chain tension to keep the chain on the correct cog. I rode easy and this worked for the most part but there were a handful of times when the chain jumped to next larger cog and immediately locked the cranks. Each time I was simply sitting and pedaling, rather than hammering it, but it still pulled the hub out of alignment in the dropouts. Might this have possibly bent something? It's the only thing I can think of that might have caused the widening issue.
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Old 01-03-15, 10:05 PM
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Six jours
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Honestly, it really does seem to me that the seatstays are being spread/bulged/sprung which is causing the dropouts to move apart. I strongly suspect that the frame is simply not strong enough for the OP. Perhaps the gentleman can hold a straightedge against the seatstays and see if they are perfectly straight.
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Old 01-03-15, 11:05 PM
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Originally Posted by Six jours View Post
Honestly, it really does seem to me that the seatstays are being spread/bulged/sprung which is causing the dropouts to move apart. I strongly suspect that the frame is simply not strong enough for the OP. Perhaps the gentleman can hold a straightedge against the seatstays and see if they are perfectly straight.
I've built and have had a number of frames with seat stays which weren't perfectly straight. A slight dog leg at the bridge is pretty common. Besides the seat stays are much less stiff or strong compared to the chain stays. Andy.
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Old 01-04-15, 01:33 AM
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CliffordK
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Originally Posted by corwin1968 View Post
Last night I remembered something that might be relevant. While I was waiting for my Surly single-speed cog to arrive, I set up my Highlander as a single-speed using a 7-speed cassette and using the long dropouts to adjust chain tension to keep the chain on the correct cog. I rode easy and this worked for the most part but there were a handful of times when the chain jumped to next larger cog and immediately locked the cranks. Each time I was simply sitting and pedaling, rather than hammering it, but it still pulled the hub out of alignment in the dropouts. Might this have possibly bent something? It's the only thing I can think of that might have caused the widening issue.
Ok, so you had it setup with no derailleurs. perhaps a poor chain-line, and a short chain.

I usually have my QR tight enough that normal pedalling won't budge the axle, but this may be something extra when the chain jumps a cog.

It is has been a long time since I've allowed my rear axle to slip, but I could imagine forcing it to slip could potentially bend something.
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