Threaded hole in brake bridge?
06-17-15, 08:45 PM
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Threaded hole in brake bridge?
Haven't been around bikes for a while, ran into this problem on my Specialized Globe Carmel. The hole for the rear brake(caliper brake) is threaded. How do I fit a conventional rear brake caliper? The shaft of the brake caliper is too large to thread into the hole in the brake bridge. I know this is a simple, silly question, but really don't know and could use the help.
Thanks in advance,
Ross
Thanks in advance,
Ross
06-17-15, 08:53 PM
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I took a quick look, and it seems that Globe Carmels have V-brakes, bot calipers. Is yours older or different? Or are you planning to change from V-brakes to calipers?
So, if the bike has canti studs for V-brakes, there's a decent chance that the bridge is tapped for a fender support bolt, and you'll need to do some work to mount a brake there.
OR
The bridge is normal, but has the nut of a recessed brake nut stuck in there, maybe rusted in place. Look at both sides of the bridge, and if you see a 6mm hex socket, then you have a nut to knock out, and the bike is ready for a 6mm caliper bolt.
So, if the bike has canti studs for V-brakes, there's a decent chance that the bridge is tapped for a fender support bolt, and you'll need to do some work to mount a brake there.
OR
The bridge is normal, but has the nut of a recessed brake nut stuck in there, maybe rusted in place. Look at both sides of the bridge, and if you see a 6mm hex socket, then you have a nut to knock out, and the bike is ready for a 6mm caliper bolt.
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06-17-15, 09:11 PM
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Thanks for the reply. It is a older Carmel with V-brakes in front. Looking at the hole in the brake bridge, there doesn't seem to be anything stuck in there, the hole in the back of the brake bridge is larger than a standard brake bolt, no threading. Is it advisable to drill out the hole in the front section of the bridge to accept a standard caliper center bolt?
06-17-15, 09:16 PM
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Get a hold of a recessed brake nut, and see if it pockets into the back side of the hole. If so, then yes, go ahead and drill the front to 6mm to accept a standard brake bolt.
If not, I can't advise without seeing it for myself.
If not, I can't advise without seeing it for myself.
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“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
06-18-15, 02:57 AM
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That looks like a fender mount. Don't you have brake posts on the seatstays?
06-18-15, 09:44 AM
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06-18-15, 09:51 AM
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Wild~ blind guess, it's for mudguards since the Brakes are, as you say, coaster brake , mounted elsewhere.
so just put a bolt in there and that will hold up the fender clip fine..
Drum brake Hubs dont need a Hole in there either..
so just put a bolt in there and that will hold up the fender clip fine..
Drum brake Hubs dont need a Hole in there either..
Last edited by fietsbob; 06-18-15 at 09:57 AM.
06-18-15, 09:52 AM
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Yes, drilling it out won't have any serious consequences, and the bridge seems to be beefy enough to handle brake loads.
The real concern is crushing the tube when you tighten the brake bolt. Usually tubes have a beefed up area to handle that, or one uses half round washers front and back to spread the load and prevent crushing. The small support flat may make using half rounds problematic, but a pocket to accomodate that can be drilled onto the washer to accommodate it.
Lastly, before doing anything, measure the brake to rim distance and confirm that you can source a decent brake with adequate reach. Be sure to allow that the necessary reach is a bit longer than what's measured at the bridge.
The real concern is crushing the tube when you tighten the brake bolt. Usually tubes have a beefed up area to handle that, or one uses half round washers front and back to spread the load and prevent crushing. The small support flat may make using half rounds problematic, but a pocket to accomodate that can be drilled onto the washer to accommodate it.
Lastly, before doing anything, measure the brake to rim distance and confirm that you can source a decent brake with adequate reach. Be sure to allow that the necessary reach is a bit longer than what's measured at the bridge.
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FB
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
06-18-15, 10:24 AM
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Yes, drilling it out won't have any serious consequences, and the bridge seems to be beefy enough to handle brake loads.
The real concern is crushing the tube when you tighten the brake bolt. Usually tubes have a beefed up area to handle that, or one uses half round washers front and back to spread the load and prevent crushing. The small support flat may make using half rounds problematic, but a pocket to accomodate that can be drilled onto the washer to accommodate it.
Lastly, before doing anything, measure the brake to rim distance and confirm that you can source a decent brake with adequate reach. Be sure to allow that the necessary reach is a bit longer than what's measured at the bridge.
The real concern is crushing the tube when you tighten the brake bolt. Usually tubes have a beefed up area to handle that, or one uses half round washers front and back to spread the load and prevent crushing. The small support flat may make using half rounds problematic, but a pocket to accomodate that can be drilled onto the washer to accommodate it.
Lastly, before doing anything, measure the brake to rim distance and confirm that you can source a decent brake with adequate reach. Be sure to allow that the necessary reach is a bit longer than what's measured at the bridge.
06-18-15, 11:19 AM
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Just checked the brake reach, need 95mm and my brakes are 73mm. Quick google comes up with nothing. Good thing FbinNY brought that to my attention. Is there such a thing as a 95mm brake?
06-18-15, 07:28 PM
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Make sure you don't use a V-brake lever with that.
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