Water bottle boss repair advice needed

[jwb96]

I'm trying to finish building up a Ridley aluminum cross frame that I'll be using as a winter commuter, using a 53t road crank instead of a smaller cross crank. Doing this, the front derailleur clamp lands exactly on the water bottle boss. My original plan was to find a way around this with a different derailleur or using a braze-on with an adapter, but I just ran into another issue: in threading the bolt into the same water bottle boss, the insert came loose. This has created both new options and problems - any ideas on which might be the best solution? Can I have new bosses installed in a better location? If I don't move them, what's the best repair for the loose one? Will something like JB Weld work?

Thanks,
Jim

[Jeremy]

If your bosses are riveted, you can usually tighten them up again by using the riv-nut installation tool. The threads need to be in good shape for this though. New bosses can be installed in a different place if you (or your shop) has the right tool. However, this requires drilling holes in your frame (there will also be a hole where the old boss came out). You can remove a damaged one by drilling it out and pushing it into the seat tube and removing your saddle. Then you can install a new one. If you don't want to use the boss, or try to find a different derailleur that will solve the problem (MTB derailleurs will not index properly with STI as the throw is different), you can mill a recess in the back of the derailleur clamp so that it fits around the boss. A drill press and a spherically shaped rotary file can do the trick. I wouldn't use JB-weld for this application.

Jeremy

[DfCas]

While the Riv-nut tool works great,if you do not have access to it,you can make a suitable tool.

Use a steel,hex head bolt that is ~40-50 mm long.Threads are M5x 0.8 pitch. Put a nut on and turn it up about halfway.Apply a mix of grease and oil on 5 or so washers that fit the bolt well and slide them on.

Turn the bolt in the rivet about 10 revs,then turn the nut down until it starts to tighten on the riv nut. Use a wrench to keep the bolt from turning while you use a second wrench to tighten the nut securely.

After its well tightened.while holding the bolt from turning,back off the nut,then remove all,and the rivet will be tight. I've used this successfully several times.

If the threads are bad,drill out the rivet and it will fall into the seattube,then install a new one using the above method.

hope this helps,

dan

[Jeremy]

Dan,

Cool tip for making your own Riv-Nut tool.

Cheers,

Jeremy