IthaDan 

See? there we go. Too bad you've already started messing with your spoke tension. You've got to learn somehow I guess.

Chris Chicago

what model trek is it?

rothenfield1

This is an ’83 Trek 500 frameset that I am trying to mod into a 9 spd. The crank isn’t 9 spd, but it seems to shift fine up front on the stand. Once I have the bike running, if the FD shifting is rough, I’ll get some ramped and pinned inner rings. I’m getting ready to take the frame to the frame builder. Hopefully he will be able to swing the rear triangle back into straightness.

cny-bikeman

I'm beginning to believe you should be very careful about building up the rest of the bike, as you don't seem to be digesting information very well. After asking for advice it took you quite a while to accept and understand what to check to see what the problem was.

Now you say you are lead to "believe" it is the frame, but your picture clearly shows you have a string run that would allow you to easily confirm that "belief." One problem, though - the strings are tied to the seat stays, not the dropouts - as both my earlier instructions and Sheldon's specify (although I would note that the illustration on Sheldon's site incorrectly shows the one side tied to the top of the dropout braze-on). On top of it the strings are at different heights on each stay, which guarantees an inaccurate measurement.

At least you are having someone competent correct it, though there's no need to "sort it out," as it's very straightforward to track a rear triangle.

p.s. Are you sure your tire is pointed in the right direction?

rothenfield1

Well, perhaps you haven’t been reading my responses; it was hard for me to check anything when I first posted the question since I was out-of-town without the bike until yesterday. I think I’ve done what any backyard bike enthusiast would do, I first try to correct the problem myself, then took the bike to the best LBS in my area with no solution, then posted the question here and through the back and forth process of this open forum have found the problem.

Thank you for your participation.

p.s. Yes, I am sure the tire is pointed in the right direction. It is backwards as the wheel has been reversed which was wisely advised that I do to confirm that it was the frame, not the wheel, that was misaligned. Have a nice day!

cny-bikeman

Sorry, missed putting in the smiley face on the tire direction - I was joking at that point.

But I stand by my feeling that you need to put a bit more thought into the process and more respect for those giving advice, as shown by the incorrect string routing and the post below:

2/7 2:14am So there's 6-7 people that suggest flipping the wheel in the frame to see if the offset reverses and you still won't try it.

Why not?

The reason I don't feel that that will do anything is because my first reaction when I saw it was to try and put the spacer from the left to right side by threading the axle through. It resulted in the offset being exactly wrong on the left side as it was the right. Go figure.

_______________________________________________________________--
There was no clear message from you that you did not have the bike available until you had made multiple posts that questioned or ignored the “reverse the wheel “ suggestion, and the above post shows you still did not accept that solution.

As for “Go figure” - it’s simple math/geometry. If you subtract 3mm from one side and add 3mm to the other you change the wheel position by 6mm – 3mm back to center, then 3mm to the other side.

Finally, regarding spacers, previous posters gave incomplete info, as spacers also affect chainline. Check Sheldon's info on that to understand why you can't just move spacers around according to the hub alone.

FBinNY 

Many assume that a wheel off center in the seatstays means the rear triangle is asymmetrical to the centerline (assuming wheel is dished). That's the most likely cause and needs to be checked by the string method.

However there's another possibility and that's a wheel that is not lying in the plain of the frame, ie not vertical when the bike is. That's more common on new bikes because it only takes a tiny error in the heights of the two dropout slots to produce a visible error - the rim will move by 4-5 times the error in the dropouts.

I detailed a method for checking this on another similar thread using a bubble level, but it takes a sensitive level (they vary). It can also be done on a flat table or floor, but probably needs two people. Tools required include a level and sliding tri-square, or other height gauge.
1- remove the rear tire and mount the wheel with the bike on the floor to ensure it's fully pocketed seated at the top of the dropout. If bike has horizontal dropouts center it in the chainstays, and tighten.

2- lay the bike on the surface with the seat tube resting on 4x4, or two equal height supports so it's parallel to the floor. Confirm with level, of height gauge at each end.

3- support the headtube or rear triangle on shims so the bike is also level in the other axis. Confirm by checking that top tube is horizontal.

4- with the bike horizontal, the rear wheel should be also, use height gauge to measure bottom and top (if in riding position) of the rim which should be equal, or lay the level on a tangent across the rim in what would be vertical if the bike was upright and confirm.

5- optional, remount rear wheel cheating so it centers on the bridge and remeasure to confirm that this solves the skew.

You repair non vertical wheels by carefully filing the tops of dropouts, but go slowly and check often because the rim moves 5 times more than the axle, so the OP's wheel would need less than 1/32" adjustment (if that's the problem).

cny-bikeman

Yes, I actually mentioned that as a more remote possibility. As the OP is having a frame builder check alignment I'm sure he can determine if that's the issue.

FBinNY 

I came to this thread kind of late, and scanned the responses before posting. I missed your1. If I'd seen it I would have opened with a +1, then moved to the method by which the OP could check for himself.

Homebrew01

The "String test" as mentioned earlier should confirm any dropout mis-alignment. You just need a long piece of string and a ruler.

FBinNY 

The string test only measures one type of mis-alignment, namely horizontal deflection. But it doesn't measure or detect errors in other planes.

hueyhoolihan

generally, the primary reason i ever concern myself with alignment is because it can effect tracking when riding handsfree. if the bike rides handsfree without pulling left or right, it is straight enough for me, and i will dish the rear wheel until it is running equidistant between the seatstays and chainstays. if it the rim cannot be positioned equally between the chainstays and the seatstays, it may be caused by a frame alignment issue, but i wouldn't worry about it. they are all bent to some degree.

bradtx

rothenfield1, I suspect that the shop is going to file the RHS drop out. Also try to pick up a pair of locater screws for the rear of the drop outs so that it's easier to align the wheel.

Brad

mrrabbit 

Are you saying that you are an advocate for building wheels that are off-dish for use in frames that are supposed to be symmetrical?

=8-)

hueyhoolihan

that sounds like a trick question. =8-)

but i'll venture a guess and say yes.

...although i'm a poor excuse for an advocate.

FBinNY 

it's a viable option if one knows exactly what the error is. OTOH it has the disadvantage of being a non-interchangeable wheel, which can be a pain later on.

FBinNY 

First rule of mechanical work, what works is right. So this might make sense for you, but again before adopting it be sure the diagnosis is correct, and it's a horizontally displaced wheel and not a non-vertical wheel.

SweetLou

I'm not sure his string test can confirm anything. I might be wrong, but I don't think the string is going around the head tube. It looks more like it is going around the seat tube. If this is the case, then nothing can be learned from his test. Oh, I just saw the top picture, it is going around the seat tube. This test shows nothing.

Also, I am wondering how the mechanic tested the frame alignment. If he did test it and everything came out fine, was the wheel in the frame? I am wondering this because the OP said it was cold set to 130, but a 135 hub is in there. The frame could be aligned, but when the stays are spread to allow the insertion of the hub, only one stay might be giving. This could lead to the problem. The only other thing I can think of is if the wheel was in the frame when tested, is that the dropouts are not aligned properly. Were the dropouts tested?

mrrabbit 

Exactly my point - doing such things are band-aids - and become someone else's mess to deal with later. If you know what the problem is - why not simply fix it. Band-aids should be a last resort...not an up front option unless the customer flat out pushes for it...

=8-)

dnomel

Are there other ways of fixing a vertical misalignment besides grinding away material? Could a framebuilder bend the frame somehow?

FBinNY 

Yes, for some adjustments, a seatstay can be bowed which will lift the corresponding dropout. But it's hard to do without being visible. But I'll answer the question with one of my own. Why not file it?

The best solution is the simplest, filing the top of the slot, both for vertical and horizontal dropouts. The next best solution, or actually just as good is to fill the high dropout by the same amount. This should be done with something with a bit of structural strength such as a bit of shim stock at the top, and JB Weld or similar to hold it all together.

I've done it this way in the past using shim stock and body filler and it held up very well, but since it'll need filing anyway I prefer to cut to the chase and file the low side higher. There's plenty of meat on a dropout and removing 1/32" or so has no negative consequence. Also, fill can break down, or fail to bond well, whereas a filed surface is every bet as good as the original.

BTW- if you have an expensive custom built frame, there's a fair chance that this was already done to super precisely dial in the wheels position.

mrrabbit 

As FBinNY mentioned, filler and file - or essentially a re-slot. Framebuilder can also heat up 'til braze filler melt point and then "slip" the joint and then check results. You can read up about the method in the Paterek frame building manual.

=8-)

FBinNY 

Yes, rebrazing the seatstay/dropout joint is always an option, and might make sense if the problem were detected during the build. but on a finished frame it's like using a shotgun to kill a mouse.

rothenfield1

I don’t know where you got the idea that I was “messing” with the spoke tension, did I say that? When I first discovered the issue, I took the bike in for professional help. It was the LBS that redished the wheel.

You know, I’ve used the BF Mech forum for a long time as my go-to place for answering questions that I could not find elsewhere, but I’m starting to feel like this forum is filled with a bunch of arrogant a-holes.

dnomel

Thanks, I feel better about filing now. But if I thought I could put a nice gentle curve on a seatstay with enough precision I'd be really tempted. Would be interesting to see someone do that.