70s fork, 2009 brake -- fit issues
03-26-11 | 01:06 PM
#1
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From: Antioch, CA (SF Bay Area)
Bikes: Trek 520 Grando, Roubaix Expert, Motobecane Ti Century Elite turned commuter, Some old French thing gone fixie
70s fork, 2009 brake -- fit issues
I have a 70s bike with a 70s Columbus tube fork. Currently is has a single pivot Royal Gran Comp brake on it.
It's connects with a bolt that goes through the crown and has a nut on the back.
It really doesn't stop all that well, even with new high quality pads.
I thought I'd replace it with a Shimano 105 front caliper I got on eBay.
The 105 bolt isn't long enough to come out the other side of the fork, and the trick bolt looks like it's supposed to go inside the hole on the fork is too fat to do so.
Is there a solution for me? Would it be wise to drill out the back hole in the fork so the fancy new bolt will fit inside?
It's connects with a bolt that goes through the crown and has a nut on the back.
It really doesn't stop all that well, even with new high quality pads.
I thought I'd replace it with a Shimano 105 front caliper I got on eBay.
The 105 bolt isn't long enough to come out the other side of the fork, and the trick bolt looks like it's supposed to go inside the hole on the fork is too fat to do so.
Is there a solution for me? Would it be wise to drill out the back hole in the fork so the fancy new bolt will fit inside?
03-26-11 | 01:14 PM
#2
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From: Thunder Bay, Ontario, Canada - burrrrr!
Bikes: 1958 Rabeneick 120D, 1968 Legnano Gran Premio, 196? Torpado Professional, 2000 Marinoni Piuma
The newer brake will have a socket head nut, as opposed to a hex nut, to fasten the brake caliper.
Later model brake bolts do not go all the way through the fork crown. Rather, the bolt goes part way through, and then the recessed socket head nut goes part way through also, but from the opposite end.
To make this work, on your fork, you will have to drill the back side hole to 8mm(I think that to be the size but you should measure your socket head barrel to be sure). That will allow the barrel of the nub to pass through the crown and reach the brake caliper bolt.
Does that make any sense?
Later model brake bolts do not go all the way through the fork crown. Rather, the bolt goes part way through, and then the recessed socket head nut goes part way through also, but from the opposite end.
To make this work, on your fork, you will have to drill the back side hole to 8mm(I think that to be the size but you should measure your socket head barrel to be sure). That will allow the barrel of the nub to pass through the crown and reach the brake caliper bolt.
Does that make any sense?
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03-26-11 | 01:17 PM
#3
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Erect member since 1953
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From: Antioch, CA (SF Bay Area)
Bikes: Trek 520 Grando, Roubaix Expert, Motobecane Ti Century Elite turned commuter, Some old French thing gone fixie
Yes, it makes perfect sense. I didn't want to start drilling if I didn't need to, or if it would create a problem.
Time to bust out the drill and locate (read 'go buy') a metric drill bit.
And thanks for the help!
Time to bust out the drill and locate (read 'go buy') a metric drill bit.
And thanks for the help!
03-26-11 | 02:23 PM
#4
Dolce far niente
Joined: Dec 2004
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From: Southwest Idaho
Curtis,
You don't need to buy a metric drill bit if you have a SAE set already. Just pick the closest one and be happy - there's a lip on the recessed bolt that should snug up just fine.
If you're in the neighborhood, bring it by.
You don't need to buy a metric drill bit if you have a SAE set already. Just pick the closest one and be happy - there's a lip on the recessed bolt that should snug up just fine.
If you're in the neighborhood, bring it by.
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03-26-11 | 03:53 PM
#6
SE Wis
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From: Milwaukee, WI
Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400, 2013 Novara Randonee, 1990 Trek 970
When I did the brake bridge on a Trek a couple weeks ago for 6600 Ultegra I meeasured the nut at 0.31" so I drilled 5/16" (.312)
03-26-11 | 03:59 PM
#7
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From: Liberty, Missouri
Bikes: 1966 Paramount | 1971 Raleigh International | ca. 1970 Bernard Carre | 1989 Waterford Paramount | 2012 Boulder Brevet | 2019 Specialized Diverge
The newer brake will have a socket head nut, as opposed to a hex nut, to fasten the brake caliper.
Later model brake bolts do not go all the way through the fork crown. Rather, the bolt goes part way through, and then the recessed socket head nut goes part way through also, but from the opposite end.
To make this work, on your fork, you will have to drill the back side hole to 8mm(I think that to be the size but you should measure your socket head barrel to be sure). That will allow the barrel of the nub to pass through the crown and reach the brake caliper bolt.
Does that make any sense?
Later model brake bolts do not go all the way through the fork crown. Rather, the bolt goes part way through, and then the recessed socket head nut goes part way through also, but from the opposite end.
To make this work, on your fork, you will have to drill the back side hole to 8mm(I think that to be the size but you should measure your socket head barrel to be sure). That will allow the barrel of the nub to pass through the crown and reach the brake caliper bolt.
Does that make any sense?
03-26-11 | 05:21 PM
#9
Thread Starter
Erect member since 1953
Joined: Dec 2006
Posts: 7,000
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From: Antioch, CA (SF Bay Area)
Bikes: Trek 520 Grando, Roubaix Expert, Motobecane Ti Century Elite turned commuter, Some old French thing gone fixie
Success!
Thanks to all! I used my non-metric drill bits and just kept going up one size until it fit. It worked and this caliper sure stops better!
105 brake on older fork by ccorlew, on Flickr
Thanks to all! I used my non-metric drill bits and just kept going up one size until it fit. It worked and this caliper sure stops better!
105 brake on older fork by ccorlew, on Flickr
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