uprightbent

Sorry for my mechanical inabilities, looking forward to the great advice always found here.....

So my back wheel on an old Trek sits squarely inside the chainstays. The dropouts are Campy and they have adjuster screws. The problem is viewing from the rear, the rear wheel does not sit at 12 o'clock under the rear brake bridge. It's slightly tilting to the non drive side. Maybe between 11 and 12 o'clock. My first thought was the dishing might be off, but if so, how can it sit so perfectly between the chain stays? Can it be straight on one axis, and tilt on another? I should insert here that while the wheel sits evenly inside the chainstays, the dropout screws are set much differently since the non drive side axle tip is further back into the dropout than the drive side. There is a small amount of vertical play in the drive side dropout, but not enough to tilt the wheel to 12 o'clock under the brake bridge. I hope I've given enough clues. This problem is making fender alignment over this rear wheel nearly impossible.

Many thanks in advance for any tips....

Bigbus

I'm fighting the same thing on my Giant MTB. I just relaced the rear wheel and trued it and it sits perfect between the chain stays but rubs on the seat stay like it's not sitting at 12:Oclock vertically. I spent most of the morning trying to straighten it out. If the dishing was off it wouldn't sit evenly between the chain stays. I'm about to take the rat tail file to the drop outs and give it a little tilt. Sorry I can't give you advice, but I'm going to be watching this thread too. Good luck

uprightbent

Thanks Bigbus. Glad to hear you also believe if the wheel sits evenly between the chainstays, it can't be a dishing issue. This is what I've been assuming.

Bigbus

That doesn't necessarily mean we're right, haha

nesteel 

Verify wheel dish before speculating any further. Also, it doesn't take much play in the dropout to affect the rim alignment as it sits over 13 or so inches away from the axis. A tiny movement of the axis grows rapidly the further from the axis you measure.

alcjphil

" while the wheel sits evenly inside the chainstays, the dropout screws are set much differently since the non drive side axle tip is further back into the dropout than the drive side"

Sure sign that the wheel dish is off

obrentharris 

Yes it can.
An incorrectly dished wheel can be made to run centered between the chain stays with the dropout adjusting screws, but it will remain off center between the seat stays.

As @nesteel says, verifying that the wheel is correctly dished is your first step to solving this problem.
Brent

Unca_Sam

An easy way to check dish is to flip the wheel around so the NDS is on the right and the DS is on the left. If the tire moves under the brake bridge, it's probably dish. How many mm are you talking about?

Can you fix dishing? I check with a cheaper one-armed truing stand, digital calipers, and lots of frustration. A dishing gauge would make it faster, but isn't necessary.

SurferRosa

I measure dish the Sheldon way, with a table, metric ruler and two stacks of cd jewel cases. I measure in two different places on each side, just in case the wheel isn't perfectly true.

You may also check frame alignment using a taut string wrapped around the head tube anchored from one rear dropout to the other. Measure from the seat tube to the string on each side.

repechage

Measure
then flip the wheel and measure again
the truth is out there

JohnDThompson 

If the wheel is properly dished, as @nesteel and @repechage suggests, and is centered at the chainstays but not at the brake bridge, the issue is likely the frame: one of the seat stays is slightly longer than the other, or the brake hole in the bridge is off-center. As long as the frame tracks straight while riding, it is a cosmetic issue that you can safely ignore.

cudak888 

If the wheel dish checks out, check the frame alignment. Your choice of the string tool or Park's alignment gauge (I prefer the Park - quicker).

Chances are the rear triangle is tweaked to the left or the right and needs to be re-aligned. Brake bridge misalignment will show up this way, even if the seatstays themselves aren't specifically bent to one side at the bridge.

-Kurt

Bigbus

I run over-sized tires (2.5") and have very little clearance to begin with. I can center it in the frame with the skewers, but the first jump I drop off it seats all the way down and the knobbies start rubbing against the seat stay again. Not exactly cosmetic haha. I also have disc brakes, but they're not effected by the movement for some reason. So confusing. Sorry uprightbent, I don't mean to hijack your thread, but our problems seem very similar.

Unca_Sam

You'll need to increase that clamping force on the QR. Does this bike have vertical dropouts?

repechage

extraneous.

Remove the tire, take advantage and insure the wheel is true.
measure the RIM to the Seatstays, Flip the wheel and measure again.

The string method is good for understanding if the frame is off to the right or left, but if a dropout is above or below the other, the string will tell no tale of that.

At the shop long ago we also had a known flat, straight rectangular extrusion about 1" x 2" and 7' long
set that to the sides of the rims as high as possible before the spokes interfere. using the rear wheel as the datum.

Unca_Sam

I've had brand new machine-built wheels that have been as far as 2mm out of perfect dish out of the box (annoying for brake setup, but that's about all). I've had used (presumably trued once or twice) wheels that want to settle out farther from 'perfect'.

uprightbent, are there any other issues besides fender difficulties? I was thinking about the 'precision' I use to center the wheel in the dropouts between the chainstays, and I'm just sliding my thumbs or fingers between the wheel and the chainstays.

Bigbus

Yeah, vertical dropouts. I might have to put my 2.35" Wardens on the rear to get the clearance. That 2.5" might be just a tad too wide. But it still bothers me that the wheel moves when it shouldn't. Right now I only have about 1/8" either side before the lugs on the tire starts rubbing. And I can tighten the QR to the point where I fear breaking the little arm off and the first time I go off a drop or slam the brakes at the same time I hit something hard and the wheel moves against the chain stay and it's rubbing again.

Bigbus

I''m sorry uprightbent, after re-reading your original post, I'm thinking our problems might not be as similar as I first thought. Have you made any progress on yours?

jackbombay

Some frames are just built crooked.

I fought this same issue with a 1988 Schwinn Premis, I measured the frame every way possible and came to the conclusion that it was "built wrong", I then had my frame builder buddy look at it, he quickly came to the same conclusion and recommended adjust the drop out with a file, but I instead chose to JB Weld a piece of sheet stainless steel to the drop out to get the wheel to sit properly. Luckily I could "lose the space" in the drop out as this frame has a Sturmey Archer hub in the back and due to the flats on the axle there is extra space between the drop outs and the axle...

uprightbent

Thanks so much for all the great advice I knew was here, allowing me to remedy this problem today.

The dishing was the issue, as I should've mentioned I recently replaced each spoke one at a time, since I've never done any sort of wheel building. This must've caused the dishing to go off center. Flipping the wheel around showed at least 5mm off center. Taking the 1/4 turn advice, which took several stages, I've moved the wheel over and it's now centered perfectly permitting an ideal fender line and alignment. Each time I've tried something I'd normally take to a shop, I realize there's so much more I can do at home and enjoy it at the same time.

Bigbus

I took the rat tail file to the drop out and modified it slightly, Then I added a grooved washer between the drop out and the skewer. I gave it a good test today, even went off a 3 foot drop as well as bouncing over some rocks and roots, hitting things at speeds I normally wouldn't and nothing moved. Everything worked fine. Merry Christmas Everyone!

SurferRosa

What? Why? Pic?

unterhausen

Campagnolo dropouts are slightly tilted down, so if an out of dish wheel is centered at the front of the chainstays it will be off at the seat stays.