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BB7 Road brake pad tabs hit IS mount

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BB7 Road brake pad tabs hit IS mount

Old 10-21-18, 11:32 AM
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benshares
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BB7 Road brake pad tabs hit IS mount

Hi - I'm currently mounting some Avid BB7 mechanical road disc brakes on a Black Mountain Cycles frame with IS mounts. I got an adapter from my LBS and it seems to be the right size/shape except for one key problem - when I put the front caliper on, the tab for the brake pad overlaps the adapter and causes the pad to be pushed forward, rubbing the rotor no matter how I adjust. Is this just a bad adapter? It's a tektro that the mechanic gave me. If this is something really basic that I'm missing please be gentle, this is my first disc brake build

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Old 10-21-18, 01:15 PM
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I'd first check that the caliper is as far inboard as possible. I like to set up mechanical discs like this by loosening the cable anchor bolt and both caliper bolts (just enough that they can slide), backing off the fixed pad, and then inserting a business card between the moving pad and the rotor and tightening the fixed pad to fix it in place, then tightening the caliper bolts. This should result in just enough clearance to the moving pad without the cable installed that it doesn't rub--if it does (and it can't be fixed by truing the rotor) then loosen the caliper bolts slightly and nudge them until it doesn't. If in this caliper position the pad tab is still hitting the adapter I would, in this case, simply cut off a small amount of the tab so it clears. IS/Post adapters do vary a bit in shaping so a different adapter may work better. You could probably remove the current adapter, mark with a sharpie where the tab hits, and compare it to other IS/post adapters to see which one has a bit more clearance in that spot.
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Old 10-21-18, 02:17 PM
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Consider if you will, .. take the pads out , bend the tab, out of the way,
then put the pads back in?

It is mostly a handle to put the pad into the caliper..


Last edited by fietsbob; 10-21-18 at 02:22 PM.
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Old 10-21-18, 03:33 PM
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I've come across the exact same situation and have just cut off a bit of the tab. I don't see any problem with this, except that pliers are needed to pull that brake pad out for changing. The brakes work normal with this arrangement. It's also a Tektro adapter that I was working this. As I don't have another IS adapter bike with BB7s to compare with, I don't know if this is adapter-specific (though I doubt it).
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Old 10-21-18, 03:45 PM
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Something doesn't quite look right. Is the adaptor facing the correct way? If it is, then yes, there is no harm in cutting the interfering tang off.
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Old 10-21-18, 04:52 PM
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Originally Posted by wschruba View Post
Something doesn't quite look right. Is the adaptor facing the correct way? If it is, then yes, there is no harm in cutting the interfering tang off.
I was worried about this - this is the only IS adapter I've seen that doesn't have any "up" indication anywhere. I'll try the adapter flipped the other way but the rotor looks pretty well centered on the caliper right now, so I can't imagine it will work. The adapter I have in the rear has a machined-out portion that is clearly there to avoid this exact issue, and I just ordered a front one online that has the same cut out. One way or another I'll figure this out.



This is the one I ordered.
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Old 10-21-18, 07:15 PM
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just snip the tang off with side cuts. done. you can still remove the pad with needle nose
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Old 10-21-18, 09:54 PM
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Originally Posted by benshares View Post
I was worried about this - this is the only IS adapter I've seen that doesn't have any "up" indication anywhere. I'll try the adapter flipped the other way but the rotor looks pretty well centered on the caliper right now, so I can't imagine it will work. The adapter I have in the rear has a machined-out portion that is clearly there to avoid this exact issue, and I just ordered a front one online that has the same cut out. One way or another I'll figure this out.



This is the one I ordered.
At least for me, I was in the same situation with the adapter installed by the factory. Trying to flip it didn't help.
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Old 10-22-18, 05:47 AM
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As previously said, just cut some of the pad tab off if you need to.


Why is there a gap between the washers and the adapter?

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Old 10-22-18, 08:34 AM
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Originally Posted by cobba View Post
As previously said, just cut some of the pad tab off if you need to.


Why is there a gap between the washers and the adapter?
Good eye! Just took the pic while loosening and tightening the caliper to see where the overlap happens. It actually overlaps more when the caliper is tightened down.
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