disc brake caliper rubbing against spokes

[grani]

Solved this exact problem permanently with my Spyre and PD-8 hub with a disc spacer (washer). It is the most sensible and simple decision. I did not have nearly enough adjustment in the caliper to move it enough sideways to clear the spokes.

[Gattonero]

Then one has to be careful with the rotor clearing the inside of the forks.
No surprise that Fox is developing new forks with tapered bottom end, right for htis purpose

[jonowinter]

Thanks again for all your replies, It's a 6-bolt PD-8 hub. I had a bit of a tinker with the calipers last night an it needs more than just an adjustment there. If I move the caliper as far as it can go to clear the spokes it's then bang up against the rotor so it definately needs "something else". I've ordered a rotor spacer as I reckon the suggestion of a rotor spacer then a washer before the fork mount (cheers reohn2) is definately a logical place to start. I've also ordered a caliper mount to try the 180 disc as I have spare rotors from my mtb so that's another fairly easy trial. I did ping off an email to specialized and my local spec lbs to get their take on the 180 rotor as that cautionary note is something i hadn't considered.

[updated] yep, lbs confirmed upgrade to 180 is not a problem and does not affect the warranty, good times !!

I have the same bike, same brake, same hub and same problem.

I was trying to sort the issue about a year ago, I ended up puting a 1mm spacer under the rotor to push it closer to the fork, this still makes the caliper very close to the spokes and the rotor very close to the caliper mount. At the time Specialized advised me not use a 180mm rotor due to safety concerns.

How is it working out for you? Does the 180 rotor give much more clearance? Any other issues you have come across?

Cheers

Jon

[virtualdynamo]

8 years late to the party . . .

I built a wheel for friend using a SON 28 ISO-6 (59mm PCD, 22.5mm center-to-flange) QR dynamo hub. The bike has a TRP Spyre calipers and I discovered the spokes rubbing on the caliper when I installed the wheel. Google helped me find this thread. First, I offset the pads inboard so I could slide the caliper outboard and the spokes were still rubbing the caliper. Second, I put 1mm washers between the rotor and hub so I could slide the caliper another mm outboard. The spokes are no longer hitting the caliper, but now the rotor bolts were rubbing the fork. I found some rotor bolts with a thinner head and now all is "well". In the not so distant future, I'll rebuild this wheel with a SONdelux Centerlock (54mm PCD, 23.0mm center-to-flange) QR hub. That is, after I check the geometry change actually gets me something.

[mattsccm]

I had much the same. Spaced the rotor out and reset the caliper.

[Brucey]

FWIW if you use 'aero' bladed spokes rather than PG you can get another ~1mm clearance. You only need to change 1/4 of them in a built wheel.

[freiston]

I had this issue with my new bike. It was a very fine clearance rub, a small fraction of a millimetre. My first thought was to use some shim washers on the disc and reset the caliper position but on inspection, the caliper was already as far out as it could go. I replaced the 160mm rotor with a 180mm one (after checking maximum rotor size advised by the fork/frame retailer) and spaced the caliper on the mount accordingly with an adapter.

Incidentally, my calipers are TRP Spyke. I haven't looked for caliper dimensions, but does anyone know if some caliper brands/models are "usual suspects" for this issue?

[Cyclothesist]

I replaced the Hayes CX comp calipers on my cyclocross with Spyres a couple of years ago. The main reason was to improve braking with twin piston rather than single piston brakes. I learned that the problem was rotor and pad contamination and I just needed to up my rotor degreasing. The Hayes were in fact just as good as the Spyres. The Spyre caliper sits significantly nearer the wheel than the Hayes. So another solution is to switch the Spyre for a Hayes CX.
There are other good single piston brake calipers out there (Avid BB7) but I don't know how inboard they sit.

[Cyckelgalen]

I am also using Hayes CX currently, and they are fine, but I was considering replacing them with some second-hand Spyres I have lying around. On a previous attempt, I gave up because they also fouled the spokes. These type of dual moving piston brakes are more likely to cause this issue because they need an actuating arm also on the inward side, and they protrude more towards the spokes.

Spyres have many other shortcomings that have been amply discussed in this forum, but I am nevertheless ready to give them a try if simple shimming and spacing out the rotor allow it. I would have thought that Spyres brake better, not because of the much-hyped dual piston actuation, but simply because the pads are two or three times bigger than the miniscule Hayes pads. The terrain around my place is very hilly, and I go through loads of Hayes pads. Spyres use the much larger and most common Shimano pad, easy to source in varying qualities and prices.
Am I correct in thinking that a larger pad, with larger friction area, will provide better braking?

Re shimming out the rotor, one good option may be cutting out the innermost section of a discarded disc to use as a shim. Regular steel or stainless washers probably work fine, but they are normally made by punch and die tooling and tend to be curved ad burred at the edges. I wonder if that is an issue that might affect the correct alignment of the rotor.

[JohnR]

Incidentally, my calipers are TRP Spyke. I haven't looked for caliper dimensions, but does anyone know if some caliper brands/models are "usual suspects" for this issue?

IRC, I had this problem with a Spyke caliper and a wheel where the spoke hole PCD on the hub was bigger than average. I fixed it with some 0.5mm washers between brake rotor and hub. Not a lot of clearance but no subsequent problems. Another alternative is to fit hydraulic brake calipers which tend to be thinner than the mechanical calipers and, for flat bar bikes, the Clarks hydraulic brake sets are very affordable.

[freiston]

Re shimming out the rotor, one good option may be cutting out the innermost section of a discarded disc to use as a shim. Regular steel or stainless washers probably work fine, but they are normally made by punch and die tooling and tend to be curved ad burred at the edges. I wonder if that is an issue that might affect the correct alignment of the rotor.

The sort of thickness that I was thinking of shimming out would have been in the region of 1mm (or less); I would think that a DIN988 shim washer, compressed by a torqued up machine screw, would cause no significant issue due to alignment. Also, I believe that purpose-made shimming rings are available.

[Brucey]

.....Am I correct in thinking that a larger pad, with larger friction area, will provide better braking?....

only if the smaller pad routinely overheats. The larger pads ought to run cooler and last a bit longer too, but if you really want a hub brake where the friction material lasts well, get a drum brake.

[Cyckelgalen]

My prime concern is improved braking performance, rather than pad durability.

Not that I know anything about tribology, but, out of common sense, I would assume that a larger friction area will improve the brake's performance. Or is it only if more force is applied in conjunction with a larger friction area?

Braking is essentially converting the bike's kinetic energy into heat through friction, that then dissipates into the air from the pads and rotors. A larger pad should be more efficient in both converting and dissipating that heat. Plus, it might take longer to overheat, that leads to reduced friction: brake fading we cal it.

To the untrained eye, it appears that a larger a friction area is always desirable, or is it? Motor vehicles tend to have larger pads on the front wheels, where most of the braking happens. And they have larger tyres when more grip, that is friction, is needed.

[Jdsk]

My prime concern is improved braking performance, rather than pad durability.

Not that I know anything about tribology, but, out of common sense, I would assume that a larger friction area will improve the brake's performance. Or is it only if more force is applied in conjunction with a larger friction area?

Braking is essentially converting the bike's kinetic energy into heat through friction, that then dissipates into the air from the pads and rotors. A larger pad should be more efficient in both converting and dissipating that heat. Plus, it might take longer to overheat, that leads to reduced friction: brake fading we cal it.

To the untrained eye, it appears that a larger a friction area is always desirable, or is it? Motor vehicles tend to have larger pads on the front wheels, where most of the braking happens. And they have larger tyres when more grip, that is friction, is needed.

The first trick is to realise that what we are commonly taught as the "law" of friction is only an introductory taster to a very complicated menu. F ≤ µ N implies independence of both area of contact and relative speed, but neither of these is necessarily true in real situations. And the coefficient of friction may look like a constant but be something quite different in practice.

"Friction":
https://en.wikipedia.org/wiki/Friction

Jonathan

[plancashire]

...
Yep, lbs confirmed upgrade to 180 is not a problem and does not affect the warranty, good times !!

My touring bike was built from the start with a bigger rotor at the front. You want more braking power there as it's more effective.