I bought a vintage Trek frame and was building it up with a modern Ultegra wheelset when I noticed that the rear wheel was about 4mm off-center of the brake nut. My first thought was that the wheel spacer was on the wrong side of the wheel, so I tried threading the axle through the hub so I could place the spacer on the other side. The result was that the wheel was now off-centered to the other side. Feeling that I had a bad frame, I took it to the most seasoned bike mechanic I know. He took a bunch of measurements of the frame and everything looked good. He told me that the bike should track fine because the wheels are in line, I will just have to adjust the brake pads accordingly.

It sucks because the seller of the frameset surely knew about the misalignment without telling me. Has anyone any ideas about what could have caused this?

Did you check the dish first? Did the wheelset come with the frame or from somewhere else?

Try putting the wheel in backwards. If the wheel becomes off-centered the other way it means that the wheel needs to be re-dished. This is a fairly simple procedure and is done by adjusting the spoke tension to center the rim.
It you have horizontal dropouts, couldn't tell from the picture, the axle needs to be adjusted in the dropouts. I'm surprised that the mechanic didn't explain these things to you.

As I said, I bought this '83 Trek as a frameset so I never saw it with wheels until I mounted my modern 28-622's. The frame has been coldset from 126 to 130. I asked the old Bianchi mechanic if the frameset had not been done properly and he said no. He also checked the wheel dish. I was kind of pissed at the mechanic as well because he charged me $40 to hand me back the bike in the same shape it was in when I gave it to him.

The bike mechanic who looked at the bike is one of the best and well established Bianchi dealers in my area. He measured the frame and checked the dish. I was a little surprised that he had no answer to why the wheel was not centered. I assumed, as you suggest, that the axle could be moved over to center the wheel. But, I have to trust the old mechanic if he says that's not the solution.

I agree, that's kinda weak if nothing was resolved. I don't charge if it's not better. Figured you probably checked the dish but it was just a thought... that's a tough one man. Best of luck!

Thanks, the mechanic says the offset wheel should have no effect on riding because the wheels are lined up straight. The problem is that I will never be able to sell the bike because I would feel obligated to point out and explain the offset, which I'm sure will freak-out any potential buyer.

if it were my bike i would just take about five minutes and loosen the driveside spokes about a turn or two then tighten the non-drive side the same amount. if you do, you may be surprised at the result.

flip the wheel in the dropouts, if it's off center the same amount the other direction, you have a dish problem. If it's exactly as off center in the same direction, you have a frame problem.

Horizontal dropouts? try sliding the axle around, you might be able to remove the misalignment. ... if it isn't a dish problem.

+1

Install the wheel backwards and see where it sits then. If it's in the same spot, the frame is probably bent. If it's off to the other side the wheel needs to be re-dished.

Agreed that with horizontal dropouts require you to center the wheel yourself when you install it in the frame, but usually it's off center between the chainstays rather than the seatstays.

Well, we are going around and around. As I said, I tried recentering the axle myself, then, not wanting to screw-up a new ultegra hub, I took it to an experienced mechanic who also thought the wheel needed to be redished. It did not, and he took a lot of time measuring the frame and it is straight. I had assumed that the hub just need to have the axle centered with the right spacers. But, if the old experienced bike mechanic could not see that, either I have misjudged him, or it is something else.

so, did you mount it in the dropouts backwards or what?

not that I doubt an old mechanic, but I do doubt his eyes- it doesn't take much difference in a corner to corner measurement to set a wheel 1/2" off center. Like 1/16" over the run from the headtube to the dropout.

Wondering the same thing.

I’m not sure how you could mount a rear wheel backwards. However, I still think that the wheel should be able to be corrected. The Ultegra hub has about a 3mm spacer on the left side, so when I first mounted my wheelset and noticed the wheel was offset to the right, I assumed that the spacer needed to be on the right side. So, I removed the lock nuts and rotated the cones to thread the axle to the right. Then mounted the spacer on the right. I ended up with the wheel now off center to the left.

Hell, I don’t know, either I greatly over estimated the greatness of this bike mechanic, or something bizarre is going on here.

backwards= put the the cassette on the side without the deraileur/ the lever end of the skewer on the side with the deraileur. Obviously, you can't ride like this, but you can get a great idea of what you need to fix.

I tell my students all the time to not trust the centering of our fancy pants park truing stands and to flip the wheel every now and then to make sure the caliper is still telling the same tale.

I wouldn't loosen the drive side at all. It is a simple matter to tighten the left side spokes to pull it in line and keep the tension on the drive side.

Those look like horizontal drop-outs without the centering bolts installed. If that's the case the wheel looks a little crocked as well as offset. Try aligning the wheel with the chain stays and see what it looks like.

sounds like you are fixated on spacers being the root cause of your problem as described. if the rim just needs to be adjusted left or right by tightening or loosening spokes (aka dishing) as has been suggested here by multiple posters, the mechanic you took it too is right. spacers aren't the issue. spacers can be judged to be appropriate with NO tire, rim or spokes on the hub. so there is no connection between the use of spacers and the problem you describe. spacers serve to position the hub between the dropouts such that when the cassette is mounted there is sufficient chain clearance between the small cog and the dropout and a match to the rear spacing.

Good thoughts, it indeed doesn’t have the centering bolts on the drop outs. But the aforementioned bike mechanic said that he checked the frame alignment and it was straight. It’s either the wheel or the frame. I had the wheelset mounted on a modern bike before and don’t recall this issue, so I’m assuming it has something to do with the spread coldset triangle. Or perhaps a frame building flaw.

Here is the bike that I am working on.

+1

The hub can be correctly spaced out even if it is not laced up to a rim. This is generally correct from the factory, but if starting from scratch there are two simple rules: 1) the cassette/freewheel should be as close to the right dropout as possible without anything interfering. 2) the left side is then spaced out to match the frame's spacing.

Messing with the spacing to fix an off-center is only creating a new problem rather than fixing the real cause of the existing one.

Yes, do this and see where you are at that point.

If your wheel was straight in another frame all signs point to the frame being bent, or the wheel just isn't being centered correctly when mounted.

I get the impression that this is what my Mechanic was referring to when the first thing he said after seeing how I had taken the spacer off the left side and put it on the drive side was, " we need to put that spacer back where it belongs."

Random thought... try measuring the dropout opening. If it's an old frame one could be slightly bent or worn which would throw the wheel off between the seat stays even if the frame is aligned and the wheel is properly dished.

What do you mean by the dropout opening?

The spacing, which, as you already posted has been enlarged from 126 to 130mm.