Chainstay Misalignment!!
 

Right when I thought I was finished cleaning and rehabbing a mucked-up 1982 Univega Viva Sport 12 spd, I noticed that the brakes didn't align with the wheel. The wheel was centered between the chainstays at the BB, but it was about 4-5 mm off center at the brake mount.

When I was servicing the pedals, it was clear that the bike had been through a couple of nasty spills. The derailleur hanger was torqued in some weird way as well, but I was able to get that nicely aligned to the chainring, or so I thought.

Chain replacement and brakepad replacement were the last two things I did. The chainline is off to the point that there is significant rub on the large chainring when the smallest rear and front gears are in action. The brakes can be set off to the side and work fine, but it's clear that they are crooked.

I really don't want to strip the bike back down and cold set the chainstays back into alignment. Plus, I don't have a gauge, so eyeballing it might not give me the result I am looking for (i.e. might f*** it up worse). I don't think I have an alternative, though, besides just leaving it. The fact that it's symmetrical at the bottom, but off on the top leads me to believe that it's twisted.

I'm mostly just sounding off my frustrations here, but if anyone has advice, I'd appreciate it. I think I'm just going to do my best to twist that metal till it looks right...

:backpedal:

If you don't have access to tools and have never done it before, I'd take it to a good LBS.

I bought the bike for a bit of prechewed bubblegum and one isotoner glove. I'm trying to dress this thing for sale, and that would definitely kill my profit. There's one place in Sac with an honest mechanic, so I might give him a call...

ride it. 4-5mm is not that much, if the bike is already built ride and see if it tracks OK. if there are issues perhaps there is someone near you willing to help. there is some home method using string but I never tried it and would not recomend to a newbee.

what kind of brakes? there should be flats on the back side of the centerbolt so you can use a 14mm (maybe 13) come wrench to center them on the wheel

Get a two by four and a string and align away. Honestly, this is How I Check and then Align Stays. The task is not all that difficult but I would suggest getting a friend to assist.

http://www.mytenspeeds.com/My_TenSpe...k_String_1.jpg

You might want to look through the whole article, since other things should be checked and adjusted as you center the stays.

I actually had the same problem, but, it may have been a different issue: chainring flipped around
That's easy to check for. You should have 8mm spacing (assuming 5x2 speed) center-to-center. I had 5mm spacing. The chainrings had no markings at all, through me off. Hope this helps...

One side of the rear triangle must have been bent upwards to cause the brake bridge to wheel misalignment. sight down the tubes from the dropouts and see if you can see a bend or curve at the bottom of one of the chainstays. You can also do a string test and compare the distance from the dropouts and the seat lug centerline or head tube. If you are willing to, you might try to do your own cold setting if you can pinpoint exactly where the bends are and where you might want to apply some force to get it back to alignment....at your own risk, of course.

Chombi

Search online and find the string/measurement system of aligning the dropouts. Also might check if wheel is dished correctly. You could check that in the frame once the dropouts are centered by flipping the wheel. Not an impossible fix, but requires a little care and precision: easier with the tools.

Oh, I'm willing to. I hadn't thought of the string gauge method, though. That might be the assurance I'm looking for.

I was just incredibly po'd to figure this out after I spent all that time getting everything mounted and adjusted. I want to market my bike as "pristine", not "slightly bent" :)

I'll go back and measure, then decide if I want to take a chance testing the physics of cro-mo

This is definitely my backup plan, but I gotta try to get it juuuust right, you know?

As Chombi said, if the wheel is dished correctly but it is offset at the top of the wheel, then one of the DOs must have been moved up or down. It's hard to imagine how that would happen without visible damage to a seat stay. The other possibility is that the wheel isn't dished correctly. In that case it would be offset at both the top and the front but you (or anyone) might correct for that simply by repositioning the axle before tightening the QR skewer. Since we don't know how you are positioning the wheel we can say no more about that.

However...if the stays are just pushed to one side you can re-dish the wheel to re-center it. As long as you don't move that wheel to another bike or dish it so much that the drive side is over-stressed it will end up perfectly aligned. The DOs and therefore the entire axle and hub will be a bit to one side, but the dishing will have brought it back to center.

Got down to it this weekend and cold set the rear triangles back into alignment. They were a few mm off, as noted, and now it's as good as new. The string measurement method, plus Sheldon Brown's leverage technique for cold-setting did the trick. One dropout was higher than the other, but that was due to the fact that the bend occurred at the brake bridge, creating a swinging motion.

Once that was taken care of, The chainline was better, but still off. I needed to re-space the axle, which was fairly simple and involved getting a new, thinner cone on the left side and adding a commensurate spacer to the drive-side. I dished the wheel about 3mm to the right, and I think all of my problems are fixed. This thing's ready to go!

Thanks all!

Congrats man. :)