Front brake calliper attachment to fork crown

geoff_ss

I've just built up a bike with a Kinesis Tk Racelight frame. It has mudguard clearance and eyes.

I'm using Shimano RX100 (57mm drop) callipers. I find the fork crown is so wide (it's the recommended 12K carbon fork) that the pivot bolt is only just long enough for the allen nut to engage the threads. It just reaches with the front mudguard bracket (about 1.5mm) behind the brake but not by much. Even without the mudguard there don't seem to be many threads holding the nut on.

I'm concerned that under heavy braking on long descents (the bike's set up for hilly riding in mountains) the thread could strip under tension with obvious and unpleasant consequences. A possible solution is a longer reach nut. Are such things available? I suppose I could drill the fork crown out so that the nut recess is deeper but that doesn't appeal though I think the crown is aluminium rather than carbon.

Ideas?

Thanks

Geoff

redddraggon

You should have got longer nuts with the fork if it's a carbon fork.

I think you may need to contact the seller of the forks if you didn't receive any longer nuts.

geoff_ss

Ah, thanks for that RD. I was going to give the shop a ring today but they're closed on Thursdays. I'll give them a ring tomorrow and have a ride over if they have some. They got me the frame in and I've bought a lot of the stuff from them so it shouldn't be a problem. They're very knowledgeable and helpful.

Is this a common problem with carbon road forks?

Geoff

redddraggon

Geoff_SS wrote:

Is this a common problem with carbon road forks?

I've only got one carbon fork and that came with the longer nuts, so I think it's only a problem if you don't get the nuts initially.

I tried looking on the web for any references about the longer nuts, but I can't find any, so I don't know where I got the info from. I think most, if not all, CFRP forks come with the longer nuts though.

andyrr

Ultegra brakes I bought the other day had 3 or 4 different length nuts for the brake bolt included as part of the package.

JWSurrey

Dude, if no luck, check out SJS Cycles' website - type in "bolt" in to the search criteria - then spend the next millennia going through the 10+ pages of bolts available for online mail order purchase!

Clerkenwell Screw in London is my normal point of reference, but it's probably a bit far, and I couldn't guarantee the quality of the bolt itself!

redvee

I made my own when I got a pair of Ambrosio forks, grabbed an old pair of canti forks and chopped one of the studs off as along as possible and screwed a shortened canti bolt in added some threadlock and put this through the forks and cut/filed to length to suit the forks. Probably could have bought one easily enough but liked the challenge to solve the problem.

geoff_ss

Well it's a regular problem it seems so I suppose there must be a readily available solution. Thanks for all the suggestions, gentlemen. I'll phone the local bike shop tomorrow am and see if they've got anything that'll do the job before I start searching elsewhere.

It's interesting that Ultegra brakes have alternative lengths supplied as accessories.

Geoff

southernfriedchicken

I had the same problem when I built my Kinesis Racelight with carbon forks. Ribble do the longer brake caliper nuts, I bought the longer one of the two so I could cut it down to size if need be. They are listed under Brake Spares.
Hope that helps.
Phil

Streak

I had the same problem when building my new Ribble winter trainer. Allister Gow of Wheelcraft ( North of Glasgow) got me the Shimano longer bolt, (there are 4 lengths listed on the Shimano website) but is also able to get one that has a threaded section sticking out the rear of the bolt, this can be used for attaching the front mudguard bridge instead of clamping it between the caliper and fork.

Streak

geoff_ss

I contacted Stanley Fearns (my LBS) this am and they'll get me a suitable allen nut for tomorrow or Monday so it looks like the problem is solved.

This is the first bike I've assembled for 12 years or so and things have changed quite a lot in some respects not always for the better. I've come across a few little snags but nothing insurmountable and (hopefully) I'll be riding my new bike in a day or so. I've learned a bit too, which is always a 'good thing' (tm)

Thanks again everyone for your help.

Geoff

secretsam

JWSurrey wrote:

Dude, if no luck, check out SJS Cycles' website - type in "bolt" in to the search criteria - then spend the next millennia going through the 10+ pages of bolts available for online mail order purchase!

Clerkenwell Screw in London is my normal point of reference, but it's probably a bit far, and I couldn't guarantee the quality of the bolt itself!

...or the gloriously named S&M Tools on Leather Lane (I kid you not)