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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 06-28-07, 08:15 PM   #1
MIN 
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Bolt of the front brake is too long for my Pista fork. Help!

I'm building up my new Pista and attempting to install the front brakes. Unluckily for me, the bolt that holds the brake on to the fork (the 5mm allen) is too long. I compared against my road bike, which has a carbon fork and the roadie has a thicker cross section. So the brakes I bought doesn't fit on the Pista's fork (the chrome unicrown fork.)

Here is a photo for reference - not mine.



The brakes I tried were $30 Shimano 550s. Suggestions for another brake caliper or alternate installation options?

thanks.
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Old 06-28-07, 08:35 PM   #2
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It is unlikely that the bolt itself (the threaded rod attached to the brake caliper) is too long. If the nut is too long, you can go to an LBS and ask for a shorter nut - multiple sizes are available. Rear brake nuts tend to be pretty short. If the bolt itself is too long, you could risk cutting it shorter (it may take some working to get the threads right after cutting (getting an M6 x 1.0 nut from a hardware store may help you get the threads working without ruining your brake nut). If your fork is really, really narrow, I guess you could use a long nut and a rear brake (which would have a very short bolt).
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Old 06-28-07, 08:38 PM   #3
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Quote:
Originally Posted by eaglevii
It is unlikely that the bolt itself (the threaded rod attached to the brake caliper) is too long. If the nut is too long, you can go to an LBS and ask for a shorter nut - multiple sizes are available. Rear brake nuts tend to be pretty short. If the bolt itself is too long, you could risk cutting it shorter (it may take some working to get the threads right after cutting (getting an M6 x 1.0 nut from a hardware store may help you get the threads working without ruining your brake nut). If your fork is really, really narrow, I guess you could use a long nut and a rear brake (which would have a very short bolt).
Great, you are on the same page as me.

LBS guys gave me a rear unit the first time by accident. So I know that is actually too short for the fork.

Are these nuts pretty universal then? I can simply go and ask for a shorter nut?
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Old 06-28-07, 08:39 PM   #4
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Washers on the front of the fork.
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Old 06-28-07, 08:43 PM   #5
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Washers on the front of the fork.
Not sure about that idea; that would generate to much torque on brake when braking. I would like to keep the distance between the brake and the fork the same.
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Old 06-28-07, 08:57 PM   #6
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As far as I know, all recent road brakes have the same threading, but just bring the caliper with you to make sure. You can always add a washer or two to the back of the fork if need be...
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Old 06-28-07, 11:42 PM   #7
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Quote:
Originally Posted by min
Not sure about that idea; that would generate to much torque on brake when braking. I would like to keep the distance between the brake and the fork the same.
Torque? Are you saying that moving the caliper farther out from the fork crown will make a longer lever arm in the form of the fixing bolt pivoting against the front of the fork crown? It seems to me that the force acting on the caliper while braking would be nearly parallel with the fixing bolt. Perhaps I am misunderstanding your problem, but moving the caliper out a couple of millimeters is not a problem.
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Old 06-29-07, 12:36 AM   #8
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Quote:
Originally Posted by MIN
Not sure about that idea; that would generate to much torque on brake when braking. I would like to keep the distance between the brake and the fork the same.

edited for my bad description.

there is little force perpendicular to the length of the bolt (up and down), so changing that length will not change the torque since there isnt realy one to begin with.

some sort of a washer/spacer is pretty standard on most brake set-ups, and may be easier than a new nut.

Last edited by roadgator; 06-29-07 at 12:43 AM.
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Old 06-29-07, 03:19 AM   #9
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Spacers.......10 for a dollar at any hardware store.
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Old 06-29-07, 12:15 PM   #10
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Like I said before, if you are concerned about the physics, but the spacers in the back.
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Old 06-29-07, 12:23 PM   #11
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I had the same situation--a Pista and a 500Ex brake and put a washer (can't remember how thick--probably a millimetre or two) behind the fork crown. Worked just fine, and it was only slightly unsightly.
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Old 06-29-07, 12:27 PM   #12
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hacksaws can do all sorts of amazing things. or go to your lbs and get the correct length parts.
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Old 06-29-07, 12:30 PM   #13
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UPDATE.

I used a chain ring spacer (10mm deep) around the brake bolt. This was in the back of the fork so the brake is still right up against the fork. Thanks for the great suggestions... I don't know why I didn't think of that.
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Old 06-29-07, 12:35 PM   #14
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you could also have just cut the nut shorter.
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Old 06-29-07, 12:40 PM   #15
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I always approach nut-cutting with some trepidation.
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Old 08-05-08, 09:19 PM   #16
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This proved quite helpful as I experienced the same problem on my 08 Pista with a set of 105 9-speed front brake calipers. Using a washer solved the problem for me. You'd think these kind of minor problems would be something they'd fix on newer models, that and the rather unconventional 1" threadless fork.
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Old 08-05-08, 09:23 PM   #17
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Quote:
Originally Posted by atelierf.lab View Post
I always approach nut-cutting with some trepidation.
as does jesse jackson
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