Campy chainring bolt hole size question...

[ultraman6970]

Ok this is a questions for the ones that think out of the box and try to fix stuff themselves...

At some point 11 speed chainrings started using a small diameter hole (record or sr i think), from my measurements roughly like 8.xmm ID and the regular hole for 10 speed is 10 mm ID. Talking about outside chainrings only, the small ones kept the 10 mm hole in them (depending on the group)

The only problem that i found is that at the time to put the bolt the bolt doesnt fit all the way down in the sit carved hole thing (no idea how is call in english sorry) but sure you guys got the idea.

Anybody have reamed a chainring hole to fit??? is like 1 mm maybe less.

Thanks.

[oldpotatoe]

Ok this is a questions for the ones that think out of the box and try to fix stuff themselves...

At some point 11 speed chainrings started using a small diameter hole (record or sr i think), from my measurements roughly like 8.xmm ID and the regular hole for 10 speed is 10 mm ID. Talking about outside chainrings only, the small ones kept the 10 mm hole in them (depending on the group)

The only problem that i found is that at the time to put the bolt the bolt doesnt fit all the way down in the sit carved hole thing (no idea how is call in english sorry) but sure you guys got the idea.

Anybody have reamed a chainring hole to fit??? is like 1 mm maybe less.

Thanks.

Crank arm spider holes got smaller, carbon cranks. I purchased a carbon crank with the larger, standard CR bolts forced into the crank spider holes. Really no big deal to make the spider holes a little larger, imho.

[ultraman6970]

Ok that means that I can actually ream the chainring big time. Since i cant find a reamer in the area of that size, next step is a file or a drill bit then. Hmm my next door neighbor has a push down drill machine thing, Will ask him. Even if the hole is tad bigger the head of the bolt fits perfect.

Gonna check the drill bits I have moving around.

[oldpotatoe]

Ok that means that I can actually ream the chainring big time. Since i cant find a reamer in the area of that size, next step is a file or a drill bit then. Hmm my next door neighbor has a push down drill machine thing, Will ask him. Even if the hole is tad bigger the head of the bolt fits perfect.

Gonna check the drill bits I have moving around.

It isn't the chainring but the crank arm spider holes.

[ultraman6970]

In my case is not, the crankset spider holes are ok, is a 10 speed chorus UT.. no idea the year... but the holes of the spider in the 11 speed chainring i want to install are like 1.5 mm smaller than any regular 10 speed chainring and 11 speed athena UT (1st gen) chainring.

[oliver1850]

Drill to 3/8" in drill press, then run this through.

http://www.ebay.com/itm/Solid-Carbide-Reamer-10mm-or-3937-in-0005-/232038354006?hash=item3606904c56:g:qEMAAOSwaB5Xo0X E

I'm assuming 10 mm is what you need.

Counterbore is the word you were looking for. Without it, the heads of the bolts are going to stick up about 2 mm rather than being flush. Here's a Daytona crank that I put the big ring on backwards to illustrate. To do the counterbore in a drill press you would need a 12 mm end mill with a 10 mm pilot. Not sure if such a thing exists. It could be done with a plain end mill, but you'd need to be able to clamp the ring to a table with x and y adjustment and center each hole with the machine spindle.

[ultraman6970]

Exactly like in the picture is what is going on, the new UT bolts for chorus and record have like a double neck and the litle neck is 10 mm, so in this chainring in particular since the hole is like 8.5 mm instead of 10 the bolt gets exactly like in the picture.

Gotta ask my neighbor he has a press drill.

Thats a nice reamer but what i need would be better an adjustable one, so I can just adjust till I get to the right size.

[ultraman6970]

Ok... went to my life saver neighbor and we use his small press drill, I can say that the process worked like a charm overthought still need to file like a tiny tiny tiny bit at each hole because the bit bit was tiny smaller than 10 mm but so far I can say that it worked. Besides I have some aluminum to cut from the edge of the holes that is natural that happens.

While watching tv will have fun with the file.

Darn aluminum is super hard, insane.

[ultraman6970]

Ok, like 3 minutes of filing each hole so the bolt sat perfectly flush.

Mission accomplished :D