5

I've just bought a new (Planet X) Holdsworth Stelvio (http://www.planetx.co.uk/i/q/CBHOLSTELTIAG/holdsworth-stelvio-shimano-tiagra-4700-touring-adventure-bike) and am having a problem with the front disc brake rotor being too close to the brake mount/adapter.

The lower bolt & washers holding the caliper to the adapter are less than 1mm away from the rotor and the caliper is adjusted fully outwards (away from the rotor) at this point. On spinning the wheel there is no contact, but whilst riding and putting any pressure through the frame there is nearly always contact between the rotor and the washer/adapter.

rotor1 rotor2

Note: next two images with bike upside down

rotor3 rotor4

The brakes are Avid BB5s as come standard on the Tiagra build of the Stelvio.

So far I've tried: - tightening the bolts holding the adapter to the fork, - adjusting the caliper position (though there is little movement since the rotor is too close), - wheel is correctly seated in the fork, - checking the truing of the rotor - it is true (brand new rotor).

I can only think that there might be an issue with the hub, somehow placing the rotor too far out on the left hand side? So far, the manufacturer have been helpful, but have only suggested things I have already tried.

Any ideas?

  • How do you know there's contact while you're riding? I had an MTB with very close spacing, but not that close. Adjusting the caliper position can be tricky - perhaps you could have your bike shop take a look? – kabZX Jul 7 '17 at 17:21
  • 1
    Hey thanks for the reply. When there's contact, there's an audible dinging noise. Not disimilar from pad rub, but much louder and more metallic. It's almost impossible to adjust the caliber position since it's basically in contact with the rotor at all times. Local bike shop suggested it would be better to get the manufacturer to deal with it since it's so new and under warranty, but I think it does need a hands on professional opinion. – phzdw Jul 7 '17 at 18:58
  • Did you back off the inboard pad before trying to recenter the caliper (the "out" direction on the inboard adjustment knob - last photo)? If the inboard pad is already set close to the rotor (as it should be for Avid mechanical) this could be the reason why you got little movement when you tried to adjust the caliper position. – Rider_X Jul 7 '17 at 19:16
  • Hey thanks for the comment. The issue is not related to the caliper position, it's that the rotor contacts the washer on the bolt holding the caliper to the adapter. This part is fixed relative to the rotor and doesn't move on caliper adjustment. – phzdw Jul 8 '17 at 12:44
3

It's not the hub's fault unless somehow its axle hardware is put together wrong or it's otherwise not putting the rotor in the right spot, but that would be a weird problem, whereas forks and frames with the issue you're having are an unfortunately common one. Step one could be downloading the IS disc mount standard and confirming it's the fork's fault.

It appears the fork tabs are unfaced. It's possible that simple facing, or even just sanding off the powder/paint, could buy you the space to make it work.

If not, the main option to make this physical combination of parts work, presuming there's adequate material for it, is file off some material from the tabs and then finish by facing it again (don't try to do it all with a facer). Either that, messing around with filing the washers (might actually be a better approach if they're what's seeming to invariably hit first), or a different brake that might have marginally better clearance, or get them to send a less borderline defective fork.

  • 1
    @Criggie Edited to clarify. – Nathan Knutson Jul 8 '17 at 3:08
  • Having worked on this a little more, it seems like the only real issue is with the positioning of the fork tab. Either it has been badly designed so that it's 1-2mm too far in, or it has been brazed on incorrectly somehow. Perhaps it's just not straight. Alternatively, it could have been bent/twisted in transit. Or like you say Nathan, it's that the fork tabs are unfaced. – phzdw Jul 8 '17 at 12:49
0

I had a look against my BB5s and the problem is your pads are retracted way too far into the rotor body.

I would loosen the adjustment bolts, make sure the pads are at least 2mm closer to the rotor by using your barrel adjuster (on the BB5, this is your only point of adjustment for the outer rotor) and then recenter the calipers and then tighten the adjustment bolts.

  • There's no room, look at the second to last picture. – Nathan Knutson Jul 8 '17 at 4:27
  • 1
    I think that's the symptom not the cause. It's not even clear if the outboard rotor is properly installed. – RoboKaren Jul 8 '17 at 5:05
  • Hi @RoboKaren, thanks for the comment. Just to reuse a comment from another reply: "The issue is not related to the caliper position, it's that the rotor contacts the washer on the bolt holding the caliper to the adapter. This part is fixed relative to the rotor and doesn't move on caliper adjustment." – phzdw Jul 8 '17 at 12:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.