Record-12 brake clearance update

[Ozz]

Originally Posted by RoosterCogset

in today's world, that's kinda scary if a modern 12s caliper rim brake can't accommodate 25s.

It might depend on the brake bridge and fork crown placement....

[joevers]

You need to attach the cable. The return spring is pushing the arm down towards the tire with no tension as you're seeing.

[ntb1001]

Originally Posted by RoosterCogset

in today's world, that's kinda scary if a modern 12s caliper rim brake can't accommodate 25s.

It is a vintage steel frame so I get that tolerances are different now...but I’ve built vintage frames with 11 speed campy group sets without any problems before.


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[Mark McM]

Originally Posted by Keith A

Just curious, is this adjustment only on the 12-speed and not the 11-speed?

The centering adjustment screw is found on nearly all dual pivot brakes, and is a necessity on direct mount brakes.

[Mark McM]

Originally Posted by RoosterCogset

in today's world, that's kinda scary if a modern 12s caliper rim brake can't accommodate 25s.

The biggest variable in clearance above the tire is the height of the brake mounting hole, and that is dependent only only on the frame/fork. Caliper design can only get a few more millimeters at best. With a frame designed for them, modern 12spd calipers can easily fit 32mm tires.

Another factor is that modern rims are getting wider, which lets the tire expand out wider/taller, so a "25mm" tire might end up being closer to 28mm on a wide rim.

[Keith A]

Originally Posted by Mark McM

The centering adjustment screw is found on nearly all dual pivot brakes, and is a necessity on direct mount brakes.

Thanks. Yes, I'm familiar with the centering adjustment screw, but I thought the adjustment being discussed here would modify the height of the calipers.

[Mark McM]

Originally Posted by Keith A

Thanks. Yes, I'm familiar with the centering adjustment screw, but I thought the adjustment being discussed here would modify the height of the calipers.

The centering screw won't modify the height of the caliper at the center pivot, but it can modify the height of the offset pivot, and the arm that rotates on the offset pivot. First you adjust the centering screw to move the caliper closing point to the left, then you rotating the entire caliper on the center mounting bolt back to the right. This rotates the offset pivot up and to the right, raising the arm that rotates on the offset pivot.

[Keith A]

Mark -- Thanks for the explanation.

[Black Dog]

How much clearance are you getting when the pads are a few mm from the rim? Where are the pads located in the slots on the calliper arms?

Also, if the frame is 90's vintage it is almost certainly designed with 23 mm tires and narrow rims in mind.

[ntb1001]

Originally Posted by Black Dog

How much clearance are you getting when the pads are a few mm from the rim? Where are the pads located in the slots on the calliper arms?

Also, if the frame is 90's vintage it is almost certainly designed with 23 mm tires and narrow rims in mind.

With the cables attached and set up...there is a bit more clearance. It should be enough to make it rideable, but it’s still tight.
I built up other bike and have never had it this tight. This frame must have closer tolerances. Might have to look for some 23mm tires for a little more room.


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[Black Dog]

Originally Posted by ntb1001

With the cables attached and set up...there is a bit more clearance. It should be enough to make it rideable, but it’s still tight.
I built up other bike and have never had it this tight. This frame must have closer tolerances. Might have to look for some 23mm tires for a little more room.


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You can add a spacer to the rear brake to get a bit more clearance. Make sure the nut is long enough if you do. I had to do this on one of my bikes to run 25mm tires. Works like a charm.

[alexandrumarian]

I would say there is no going around the fact the new brakes have less clearance than the old. And no faffing around the screw will change it much, besides that screw is supposed to be used for centering not maxed on some weird spot... The truly important parameter is how the fork is drilled, period.

I am a big Campy fan but I felt cheated after spending 300e on my SR12 only to find the marketing was bull (more clearance). I had switched to 27mm tubs from 25, and clearance (2015 Record) was tight, about 2mm. I could feel debris or twigs sometimes getting caught. I hoped the new brakes will have about 1-2mm extra making it perfect, but no. With the new brakes it would not work at all, had to change back to 25. In retrospect I should have sent them back, even if they look pretty cool...

BUT in retrospect the screw method does seem to help. Wish I had figured it out before tearing that tub So basically, unscrew the centering bolt almost fully (you still want a modicum of easy adjustment) then recenter the brake from the main mounting bolt.

[jacrider]

Originally Posted by RoosterCogset

in today's world, that's kinda scary if a modern 12s caliper rim brake can't accommodate 25s.

I just re-built a 25 yr old steel frame with new Campy Chorus 12 speed. I have no problem with 28mm tires. Could probably fit 30's. I think this issue is the height of the brake bridge. As noted by others and the OP's subsequent posts, cable tension will make the two brake arms go up, providing better clearance, but the brake bridge will be a critical factor.

[fignon's barber]

I think the issue is not so much the brakes, but the frame and tires. Remember Vittoria Corsa Control are oversized 25mm. On most rims, they run closer to 28mm. Framesets of that era ran 19,21,23mm tires usually, and Pinarellos were known for their tight geo and snappy handling.

[oldpotatoe]

Originally Posted by RoosterCogset View Post
in today's world, that's kinda scary if a modern 12s caliper rim brake can't accommodate 25s.
...

Originally Posted by Ozz

It might depend on the brake bridge and fork crown placement....

Not might but does. BTW-Chorus calipers of this era have more clearance, clarence.

Vintage Pinarello frame...