Bicycle Mechanics - 24mm bars with a 23.8mm stem clamp?
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09-28-09, 06:04 PM
I'm looking for some bullhorns for my mid 80s bianchi roadbike>fg conversion. The stem has a 23.8mm clamp but the closest size bars I can find is 24mm. I know I could just flop and chop the stock drops but I'd prefer not to in case I want to go back to them later. So I'm wondering will 24mm bars fit in my clamp?
09-28-09, 06:57 PM
It is a bit of a stretch to do. Will they fit, yes. Will you break your stem, maybe. Will your scratch up the new handles putting them into the stem, probably.
That being said you have 2 options
1-get a new stem to go with the new bars-this is the best option and will be safest too
2- you can force this bar into this stem and here is how to do it. Use a small torch to heat up the stem at the top of the clamp(side opposite where the bolt goes. Once heated up you can use a large flathead screwdriver to pry the clamp open a touch more. You should be able to squeezee the new bars into the now larger clamp. The trick will be getting the bolt to screw back in. You may have to use a file or dremel to open the non-threaded hole at the bottom of the hole just a bit to make up for the new threaded hole angle.
Fudging it is very prone to issues, I wouldn't do it with a cheap cast quill stem, but a forged stem I might try it on.
Dangers are you will break your stem when trying to bend it open(heat will help). The other problem is not being able to screw the set bolt in after prying it open a bit.
Also please be aware that doing this may CAUSE CATASTROPHIC FAILURE on a ride, ie you stress the stem more than it can handle and then it breaks in the middle of a hill climb or something.
I'd just get a new stem to go with the new handlebar, or do a flop and chop on your drops.
09-28-09, 06:59 PM
if you want to cut your handlebars use a pipe cutter rather than a hacksaw. It is cleaner and more precise, and a cheap pipe cutter is a good investment.
09-28-09, 07:00 PM
You can also try getting some smaller handlebars and shimming them up to fit your stem using strips of metal cut from an aluminum can.
09-28-09, 07:01 PM
RVA holla- Dude, go to recycles and see if they have a stem that will work for you. They probably have something cheap. Or if you want i can get you in touch with my boy Dirty Dan who has all kinds of old parts in his garage.
09-28-09, 07:45 PM
I've always read that the 25.8mm and 26mm bars/stems were compatible so I would imagine that 23.8 and 24 would be, too. If it were me, I'd do it.
edit: I just looked up my Ritchey stem and found that it is 25.8, so in fact, I have put 26.0 bars (Syntace) in a 25.8 stem.
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