I want to fit some bar end brake levers to set of bullhorn bars. The internal diameter of the end of the bars is about 18.2 mm. The brake levers need 19.6 mm. I'm thinking the best way is to ream out the end of the bar - they are pretty thick so I'm not worried about weakening them.
Can anyone suggest a reaming tool for the job? Bars are aluminium.
I'd file the bungs on the brake levers first. That's a lot of metal (0.7mm).
I'd suggest using a die grinder with a diamond bit.
I did wonder about a die grinder. I'm just not sure if I could do a neat enough job.
Filing the lever bung is plan b, because the bars are too tight anyway to get normal bar tape bungs in (haven't decided yet if I want bullhorn brake levers yet)
i had the same issue and filed down the lever bungs. I am guessing same cheap bullhorn bars - I wouldn't want them any thinner - the alloy was very soft
You just let the die grinder run it's own way around, looks easy, although I'll be honest I've never tried it. You could always practice on a spare bit of tube.
Looks like you have about 1.4mm to take off, thats too much for a reamer in a single step really.
If you had some adjustable reamers, you could do it in steps, or even if it was a standard imperial size you go up in reamers in stages, but 19.6mm is not really any commonly sized reamer, the nearest youre likely to find would be 49/64ths , which comes out at about 19.4mm, but I doubt you'd find a decent one anywhere.
If you decide to go the dremel or cordless drill route, bear in mind that the soft alu will clog and glaze any abrasive stone used, so maybe make up a simple wooden mandrel and glue emery to it, or even better cut a slot in the mandrel to take easily changed strips of emery. Also you could use a small rotary burr, which takes slivers off, but be warned it can be very aggressive when cutting and leaves a dogshit finish, like very bad chatter. Might not bother you but it would bother me immensely.
Probably your best bet would be take a bit off the bungs and open the hole up slightly with emery, best of both worlds then, no one component is significantly weakened. Not an ideal situation but it is what it is.
Thanks for all the tips. Will have a play with Emery cloth first and look at the bungs. I read elsewhere that someone was able to remove part of the bung to reduce the size by quite a bit.