daniell

I have a 25 year old steel mountain bike. I was never able to balance the cantilever brakes. The bike has vertical dropouts. In order for the wheel to be centered between the brake pads, I must put the wheel off to the side. I measured the frame with a perfectly dished wheel and found the frame to be off by several MM. Should I re dish the wheel to account for the frame problem? Now that the weather will be getting cold, I prefer the mountain bike over my road bike.

shelbyfv

Steel? Straighten the frame. Measure it with string before you bend anything.

TiHabanero

If the perfectly dished wheel is closer to the drive side then dish the wheel. If the pulls to the non-drive side then tweak the frame.

Geepig

Before bending anything, does this mean you have tried the wheel in the dropouts or in a truing frame both ways around?

ThermionicScott 

+1 on this. You wouldn't want to bend the frame and then realize the wheel was actually off!

Andrew R Stewart 

Is the wheel being slightly off to one side presenting any problems? Safety? Brakes still stop you? Bike will only steer to one side? (That last one is tongue in cheekish).

Long before you start doing stuff that can harm the frame if not done well make sure you really understand the issues and their importance, or lack of importance. Andy

Iride01 

You are saying the centerline of the wheel isn't in the centerline of the frame? If so, then are the spacers on either side of the hub that can be moved from one side to the other?

As for centering up the brakes themselves, I've no idea on cantilever brakes. But some of the old caliper rim brakes I had were a pain to keep centered on the wheel.

Don't just assume the the center between the pads is the correct center line for the wheel.

daniell

I carefully checked the wheel with a dishing tool. No problem there. If I put the wheel straight into the dropouts (vertical) ?the rim will rub against the rim. I cannot move the brake any further away. What about filing one of the dropouts?

thumpism 

Sure. I've done this. Proceed carefully and check with your wheel periodically so you don't overdo it. You might still have a problem getting the brakes to move evenly against the rim but that's a different problem. Good luck!

Andrew R Stewart 

Just to try to separate two issues that might be independent of each other- With vertical drop outs one can tilt/cock the rear wheel off center a bit in the seat stay plane. If you can do this and then try sdjusting the brake you's have more info about the brake rubbing issue. While a wheel that sits a few MMs off center will sometimes worsen brake rub sometimes it will reduce it, depends on which way the wheel sits WRT which way the brake's centering can't be any longer shifted.

One reason I bring this up is that brake rub can happen very independent of wheel centering and You don't mention of previous rubbing. So if the wheel has been sitting off center since the factory (which would be the case with a less then an aligned well frame from the factory, as in no major incidents happening since the factory) why now does the brake rub? To me this suggests that something with the brake has changed.

A couple of other comments- Miss positioning the rear axle QR spring can cause the wheel to not seat fully into the dropouts on the side that the spring is on (backwards). A bent axle can cause the rim to look off center in one plane (like at the brake) yet check out as dished with a dishing tool. Andy

daniell

The bike has always been this way. I have been through 3 different wheel sets and 3 different brakes. I remember taking off the first pair of brakes that came with the bike. The post on one side was pushed all the way in and the other side was out. I always tilted the wheel to make it work. I recently checked the dish with a dishing tool and found it to be good. A similar problem exists in respect to the front fork. Before putting money into the frame, I wanted to see if I could remedy this problem. One thing is for sure, at my age, I wont have to worry about the bike lasting another 25 years.

70sSanO

This is probably your best answer on a 25 year old winter bike. If the rim is closer to the drive side chain/seat stays, dishing the wheel to fit will theoretically make a stronger wheel.

If the rim is rubbing on the non-drive side, moving the rim towards the drive side makes for a weaker wheel.

John

Andrew R Stewart 

The problem I have with dishing a wheel so the rim sits centered between the seat stays (or chain stays, pick one) when the problem is the frame is miss aligned is that the tire's contact point with the road will also shift over. Basically "fixing" one issue at the cost of the tracking of the bike.

As an example- If the rear rim is too close to the drive side (RH) seat stay the tire's contact point is to the left of the bike's centerline. When the "fix" is done and the rim is dished to the LH directing and is now centered at the brake the tire contact is now further to the LH side. Whether this worsening of the tracking alignment is an acceptable trade off will depend on the rider's ability to feel the tracking aspect. Not all riders are sensitive to this. Andy

This assumes the miss alignment is one side's stay is longer then the other. There are other ways the rim/brake/stays alignment can be off but these are far less common.

daniell

Thank you for your thoughtful and informative reply.
At present I am tilting the wheel in the dropouts. Would that have a different effect than dishing?

CliffordK

It is possible that the dropout was mounted wrong, but I'd start with frame alignment before attempting to modify the dropouts. At least run the strings from the rear dropouts to the head tube and measure at the seat tube.

Read this thread about someone who inherited a bike with a misaligned rear triangle that someone "fixed" with a file.

https://www.bikeforums.net/bicycle-m...-accident.html

GamblerGORD53

Get a long straight edge and see how it lines up with the front wheel as well. That's what I also previously did with my custom tour bike, spreading the D.O from 132 to 135. I had CF on the frame, so eyeballing was all I could do.
This year my brand new $1,000 roadster was lopsided at the seat stays. Didn't look straight with the front wheel either. Was an easy bend the dropouts fix.
It doesn't have rim brakes, but I did it anyway. I need to gauge the gaps to align the wheel, with the old style semi-horizonal dropouts.

Andrew R Stewart 

Yes the affect will be different. The effect would be both the rim/brake/stay and the contact point to the road being closer to on center. This is the goal. Andy

70sSanO

I agree that differences in dropout depth is different than a rear triangle that is off center. Dishing won’t help with that issue, as Andy pointed out, fixing the dish at the brakes just exacerbates the offset where the tire contacts the ground.

As suggested, using a straight edge, more specifically a square might help to show the tilt of the axle.

It might be possible to put the bike in a work stand and with a level get the seat tube perpendicular to the ground. Then with the wheel removed use a level to see how things line up across the dropouts, and maybe other points along the seat stays.

It doesn’t take a whole lot at the dropouts to be off by 4mm at the brakes.

John

daniell

Thanks for your input. I know nothing in respect to frame alignment. In fact, I would have trouble detecting it.

sovende

Before doing any more “adjusting”, I would do the suggested diagnostics to determine if the frame was deformed in any way. “Traumatic” deformity might be easier to tweak back to original shape. Misalignment since manufacture, not so easy. I understand why the OP may wish to ride this bike in the Winter. Wider tires, upright position, more stable, etc. Additionally, probably not riding at road bike speeds or distance. IMHO, perfect alignment might not be of prime importance but I’d certainly want functional brakes! I’d use axle spacers to center the wheel. I wouldn’t file a dropout but place a spacer on the other side to adjust wheel “tilt”. In this case, “better” might be the enemy of “good enough”!

daniell

This is the best that I can do. I put the rear wheel straight into the dropouts. One brake block is now all the way in, and the other one is much further out. I have no trouble braking as is. It has been this way for 25 years, I wont put any major money into the bike. Perhaps I will buy another bike to complement my road bike. On my road bike I am limited to 25 mm tires.

70sSanO

If both pads are contacting the rim at the same time, just ride it. After 25 years of being ridden, it probably doesn’t matter that much.

I’m no expert on frame alignment, but you can probably eye ball it enough to the seat tube to see how straight the wheel sits. After 25 years you know the tire gap to the stays. It isn’t rocket science; although a combination of issues reduces the likelyhood of an easy fix.

It’ll be Spring before you know it.

John