Singlespeed & Fixed Gear - bullhorns strippin out stem bolts

i dunno if anyone else has had this problem, but i just installed some profile design bullhorns onto a cinelli stem and motherf***er if i can't get that bolt tight enough. i mean, when i'm leaning over to do those 400' skids, the bars just slip on down! now i've stripped out the bolt trying to keep them s**ts solid. damn... someone help me out. oh yeah, i need a new bolt, too...

Bars too narrow for the stem?
Get a shim?

nah, they're a tight fit... no metal scoring though, like on my drop bars. maybe that's it?

I mean, they're obviously not a tight enough fit.

they probably aren't big enough for the stem (26.4 mm). try a shim or aluminum cans or something.

maaaaaybe... i guess i was wondering if anyone's ever had any troubles with seriously torquing bars (more pressure on bullhorns for sure) with an old (circa '80) cinelli stem. the one with the internal mechanism.

cinelli=26.4
profile bullhorns=26.0

i hope you have a good dentist

s**t, man... you just blew my quack theories out of the water...
guess i shouldn't've been so enthusiastic.
is it too tough to find a new bolt for them old stems? (thread sizing can be weird sometimes)

word,

trons is right on it... you either need a different stem(w/ 26.0 clamp) or cinelli bars (26.4 clamp diameter)

looks like i was beaten to the punch, well done bax. for what it's worth if you are lookin' to keep that stem, my lbs has some used cinelli bullhorns, i can connect you with them

Grab an old beer/soda can and cut it into a shim. I've done this on several bikes and all my teef are still in my face.

i actually thought i could pull this off myself with a soda can and a cinelli 2a, but no matter how many cans i shoved in there and how much i torqued that ****er down there was still a wobble in the bars.

cinelli=26.4
profile bullhorns=26.0

i hope you have a good dentist

+1

If your shims are slipping, try some locktite in between the layers. I had to do that on a cruiser with ape hangers. Be careful to use the right kind, or you'll never be able to get them back out again. If that matters to you.

Another solution, which I posted about once before and was thoroughly scolded for, is to get the bars lined up just how you like them with shims in place and tight as can be, then drill a small hole through the stem and into the bars and put a bolt in that fits tightly (preferably, one that you have to screw into place). (The bolt functions like the pin in a cottered crank.)

When I mentioned this a while back, everyone said I was going to die, but I used the set-up with some cruiser bars on a fixie for over six months without any slippage or catastrophic failures, and I skid a lot and hard. (And nothing bad happened after six months - I just had one of my periodic adjustment manias and went with different bars and stem for a while.)

they probably aren't big enough for the stem (26.4 mm). try a shim or aluminum cans or something.

If it is good enough for Lemond, it should be good enough for you. Eight Seconds.

word,

trons is right on it... you either need a different stem(w/ 26.0 clamp) or cinelli bars (26.4 clamp diameter)

looks like i was beaten to the punch, well done bax. for what it's worth if you are lookin' to keep that stem, my lbs has some used cinelli bullhorns, i can connect you with them

thanks... as it were, i switched back to my cinelli drop bars and found that i like them better anyway, but that doesn't solve the problem of my dang stripped stem bolt (6mm allen, shouldn't be too hard to replace, though past experience has shown that to find the perfect length, width, thread can be like finding a needle in a haystack). i'll be more careful next time...
just outta curiosity, maybe you should give me a # to that albequerque bike shop.

but that doesn't solve the problem of my dang stripped stem bolt (6mm allen, shouldn't be too hard to replace, though past experience has shown that to find the perfect length, width, thread can be like finding a needle in a haystack). .

length - various lengths are available, but no big deal if you have a saw or roto tool
Width - what are you talking about? 6mm end of story, heads are pretty standard too
thread - standard size - fine thread are the hard ones to find, and since the stem is Alum, very unlikely that it will be fine thread.

Actually, I am really surprised that you managed to strip the threads on the bolt. The bolt is harder that the (is it alloy?) stem, so the stem should strip out first, in which cast you are really screwed.

On shiming, a "sparks" can shim will bump up the dia by .0075" which is just short of .2 mm , so 2 layers will do the job. If you are going to the hardware store, and you may be able to find some brass sheets from "K&S Engineering". They make smalll brass and alum tubing, shapes and sheets. A 4" X 10" X .010" sheet will cost $4 and will make lots of good shims for your set up and even better ones for Nitto bars (25.4mm to 26.0mm)

Sorry about the attitude Gnarboots, really I should tone it down. But something about people who can't screw really set me off

Peace !

the bolt on the stem attaches onto another piece of steel on the other side, not the stem itself. but (at least on my stem) the part with an allen fitting is what the bolt goes into, not the bolt itself. i'm not sure how easy it is going to be for you to find a replacement.

F shims. You should just get a bar and stem combo which are compatible. That will always be more solid than a rigged shim job. It will be more worth it in the end. Same thing goes for seat posts. Just find the right size before you seriously F your bike up and ruin it.