[NoobHill]

OK, so I set up my old 90's Trek as a single speed and was going to use it as a trials bike for me to learn how to handle better. I picked up this bike like 6 years ago at a garage sale and never rode it very much because the derailleurs didn't work and I had a bmx bike back then. Well I decided to do some bunny hop practice first with this bike by putting an old shoe box on its side and going over that.

I made it over but when I landed the bars rotated like I was giving it gas on a dirtbike. Not to big of a problem right... wrong. When the handle bars rotated it pulled the front brake cable tight :eekster: - Whoever built this bike must have been trying to cut weight by trimming down all the cables. The front brake locked up hard :madmax: and somehow with my wrists turned below the bars I was able to skid this thing to a stop. Thank god I was doing this on grass and it was kind of wet.

So this bike has the old style threaded headset where the stem is intergrated into that whole deal. There is only one bolt to tighten the handlebars with. Is there anyway to make this secure and worry-free other than just tightening that bolt till my hands bleed?

 

[Bikinfoolferlife]

First unclamp the handlebars and take them out and inspect the bar's clamping surface and the clamping surface inside the stem, also remove the clamp bolt and clean it/regrease it. Was the bar knurled and is now stripped? Is it free of rust? If it all looks good put it back together and torque correctly (over torquing won't solve any problems but rather create them). Test before you ride!

 

[NoobHill]

The clamping surface is pretty much the same as modern bikes. It uses the parallel, linear grooves like my new bike has. The surface had quite a bit of metal dust on it that I wiped off.

I wasn't sure where to look for torque specs so I just tightened it really hard... I really ripped on it and it doesn't seem to be moving. It may have just loosened with time, but I was wondering if there were any tricks besides keeping the bolt tight.

 

[i like downhill]

chances are you probably tightened too much haha. usually bolts have a torque spec of 5nm which isnt that much to the touch. you can re-knurl it if you wanted, but you have to buy a knurler.

 

[Mr.Bob]

The clamping surface is pretty much the same as modern bikes. It uses the parallel, linear grooves like my new bike has. The surface had quite a bit of metal dust on it that I wiped off.

I wasn't sure where to look for torque specs so I just tightened it really hard... I really ripped on it and it doesn't seem to be moving. It may have just loosened with time, but I was wondering if there were any tricks besides keeping the bolt tight.

The trick is to make sure the bar/stem interface is clean, as mentioned above. Degrease and remove all residue and then don't touch it with your greasy paws before you put it back together . That's basically it though, a clean interface and properly tightened bolts.

 

[Bikinfoolferlife]

The clamping surface is pretty much the same as modern bikes. It uses the parallel, linear grooves like my new bike has. The surface had quite a bit of metal dust on it that I wiped off.

I wasn't sure where to look for torque specs so I just tightened it really hard... I really ripped on it and it doesn't seem to be moving. It may have just loosened with time, but I was wondering if there were any tricks besides keeping the bolt tight.

My modern bikes have no knurling (the parallel, linear grooves), varies with quality. The metal dust was from your knurling disintegrating most likely.

Torque specs start here http://www.parktool.com/repair/readhowto.asp?id=88

Hopefully you've got your current problem solved unless you really over torqued your stem's handlebar clamp bolt.