wild man walt 

Hello,

A friend has a custom titanium Guru frame with a no-name carbon fork. The front brake defies staying in adjustment. She has taken it to several bike shops in town to try and have the front brake calipers centered. Whenever the problem of brake being off center and rubbing one the rim is "fixed," the adjustment only lasts for a few miles then becomes off center and begins rubbing on the rim again.

She has been riding with the quick release partially open so that the brake pads do not rub on the rim, not the ideal solution.

All my bikes are Old Skool with steel forks and Campy brakes that are centered with a 13mm cone wrench. I am thinking that applying maximum torque to the nut at the back of the brake is probably not a good idea since the fork is carbon.

Anyone have any suggestions?

Thank you.

Walt

Iride01 

If these are old single pull calipers then those were a problem sometimes. Various brands needed different things and how the bike manufacturer mounted them made a difference too.

Dual caliper should be as easy as can be. So if the bike shop mechanic couldn't do it, then you must not have the dual pivot brakes. Or you didn't see a real mechanic.

The tires wheels might be the real issue. Maybe the spokes are too loose. Or the wheel bearing wobbly.


Telling us the exact model and version of the brakes will help. Also a pic or two. But you'll have to post the images somewhere else and obfuscate the URL and put it in the plain text of your message.

SpedFast

They can be very tricky and require a few tweeks after use before they stay centered. Getting the torque just right on the rear nut is key and using a wrench on that nut to literally pull them back into position each time they move and then adding just a tad more torque to it, eventually they end up centered and stop moving. With that said, I'm assuming they're not dual pivot and simply lower end brakes. I've tweeked on friend's bikes with one pad worn down and the other looking like new because of what your friend is going through. Unless it is causing a lot of drag, it's only frustrating and not overly serious. Loosening the QR to accommodate the dragging pad is much more serious. Good luck. My advice is simply carry the right size wrench with and keep playing with it till you get it right.

Andrew R Stewart 

Both single and dual pivot versions used a star washer/spacer between the mounting bolt/center bolt and the fork crown. This helps to "dig into" the two parts to better hold the rotational effort to center the pads in the rim. If this star washer is missing the mounting nut will need to be REALLY tight to hold, (and with some carbon forks this is not a good idea). If the cable casing is too short it will want to rotate/pull the caliper off center with each application of the brake. If a dual pivot version the relative motion and arrangement of the two arms comes into play. One side will move further than the other side (different length of the arms above their pivots) so for the pads to contact the rim at the same time (what my goal in "centering" the brake) means that when not being applied the pads are not the same distance from their sides of the rim.

Of course a true rim, not sloppy loose bearing adjustments both are assumed to not be at play too. And that the caliper's pivots are freely working. If a pivot wasn't free moving that pad might not retract fully. Andy

KerryIrons

My first suggestion would be to find a different bike shop. The "fix" they applied appears to be "just push the brake over" without actually moving the brake body like you did with your Campy brakes and the cone wrench. I keep my brake bolt tight enough so that I can move the brake body with strong hand force. That way the brake can get knocked off center without being damaged (like in a crash, in the car trunk, etc.). Also, she should consider riding with the brakes set a little farther from the rim. You get the most effective brake modulation when you can just about pull the levers all the way to the bar. Many people ride with their brakes set for "instant grab" and that results in poor modulation.

icemilkcoffee 

The length of the cable housing is important. If it's too short or too long it will tend to push the brakes one way or the other.

alcjphil

If the rear nut is too long the threads may be bottoming out before the calliper is tight

ClydeClydeson

It's likely that the material at the crown of the fork through which the bolt runs is aluminum, not carbon. The legs are likely carbon legs bonded to aluminum crown and dropouts.

Other things to check (most mentioned above):

1. That the 'nut' is not bottoming out on a too-long bolt and preventing it from clamping properly
2. That the wheel is in repeatably straight (axle fully seeted in the dropouts on both sides), QR springs on the correct direction and not throwing things out of whack
3. Cable is not too short or significantly too long

curbtender

Do they transport the bike with the front wheel off? Maybe they are knocking it out of alignment or not getting it centered before they shut the quick release.