Mounting brakes on a road bike
09-26-08, 05:28 PM
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Mounting brakes on a road bike
I'm in the middle of doing my first build of a road bike, i'm trying to mount stock Shimano Ultegra 6600 brakes on the bike, but it appears that the stock brake bolts that came with the brakes are too short too mount the rear brake ... Is this somewhat common? Do I just need a longer bolt for the rear, or am I doing something wrong?
09-26-08, 06:05 PM
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It would be uncommon, but if you're sure the recessed bolt isn't long enough - your LBS should stock longer ones. They come in various sizes.
09-26-08, 06:20 PM
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Is this an older frame? Is the rear tubular nut going down into the brake bridge or is it just on the surface? If the hole on the front side of the brake bridge isn't big enough to let the shank of the tubular nut fit into the tube then you'll need to drill that out. This is a tough one due to restricted access in the opening and the topic of many a past thread.
09-26-08, 06:43 PM
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Is this an older frame? Is the rear tubular nut going down into the brake bridge or is it just on the surface? If the hole on the front side of the brake bridge isn't big enough to let the shank of the tubular nut fit into the tube then you'll need to drill that out. This is a tough one due to restricted access in the opening and the topic of many a past thread.
09-26-08, 10:36 PM
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Are you sure you don't have your brakes reversed front to back?
09-27-08, 01:27 AM
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The longer bolt goes in front right 
The frame is fairly new (2007 Trek 2100, one of the last US made Aluminum trek's I believe). The rear seatstays including the wishbone area are CF, so it's pretty thick (about 35mm total thickness). As far as I can tell, I can't get the flared allen-key end of the nut to fit into the hole, so my only other option would be to get a longer brake nut?
Looking at my other bike with Aluminum stays, the distance is much shorter, so i'm assuming it's the thick wishbone area of the carbon stays that's causing the problem. Does this sound right? The frame is anything exotic, which is why i'm wondering if this is a common issue.
The frame is fairly new (2007 Trek 2100, one of the last US made Aluminum trek's I believe). The rear seatstays including the wishbone area are CF, so it's pretty thick (about 35mm total thickness). As far as I can tell, I can't get the flared allen-key end of the nut to fit into the hole, so my only other option would be to get a longer brake nut?
Looking at my other bike with Aluminum stays, the distance is much shorter, so i'm assuming it's the thick wishbone area of the carbon stays that's causing the problem. Does this sound right? The frame is anything exotic, which is why i'm wondering if this is a common issue.
09-27-08, 11:34 AM
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So the issue is that the head (not a flare) of the nut won't fit down into the hole. OK.
Is there a shoulder down inside the recess in the bridge that the head would rest on? If not then the nut is intended to have the head stay out and exposed. If there is a shoulder in the hole then the head of the nut is just a little oversized and you can fix that by mounting it in a hand drill and hold a metal file up to the head to slightly reduce the diameter until it does fit.
But from what you're saying I get the impression that the nut isn't threading onto the caliper's bolt at all. That's a whole other issue. In total you must have the nut thread onto the bolt by at least 5 turns. And even at that I'd be looking for a longer nut that provides more like 6 to 7 with 8 turns being even better. If it's not even hitting the threads or is only turning on a thread or two you'll need to look in the hole and evaulate how many more turns you'll get by reducing the head diameter if it has a shoulder inside to seat onto.
Lots of "if"s but hopefully that'll help you out. They make the holes in the frames pretty tight. If you're running with a higher end Campy or Shimano brake the tubular nuts were finely made to tighter tolerances. I've seen some that look like they came from the high end aerospace industry and others that look like they were whittled out from a bar of soap and then half melted to smoothen them up. The chromed ones in particular can be pretty cheezy looking and I can see one of those not fitting properly quite easily.
Is there a shoulder down inside the recess in the bridge that the head would rest on? If not then the nut is intended to have the head stay out and exposed. If there is a shoulder in the hole then the head of the nut is just a little oversized and you can fix that by mounting it in a hand drill and hold a metal file up to the head to slightly reduce the diameter until it does fit.
But from what you're saying I get the impression that the nut isn't threading onto the caliper's bolt at all. That's a whole other issue. In total you must have the nut thread onto the bolt by at least 5 turns. And even at that I'd be looking for a longer nut that provides more like 6 to 7 with 8 turns being even better. If it's not even hitting the threads or is only turning on a thread or two you'll need to look in the hole and evaulate how many more turns you'll get by reducing the head diameter if it has a shoulder inside to seat onto.
Lots of "if"s but hopefully that'll help you out. They make the holes in the frames pretty tight. If you're running with a higher end Campy or Shimano brake the tubular nuts were finely made to tighter tolerances. I've seen some that look like they came from the high end aerospace industry and others that look like they were whittled out from a bar of soap and then half melted to smoothen them up. The chromed ones in particular can be pretty cheezy looking and I can see one of those not fitting properly quite easily.
