Attaching handlebars to a threadless headset

[terrordactyl]

I just recently bought a bike online, and had received it with minimal assembly required. I'm having a tough time attaching the handlebars to the headset, however. When tightening the four clamping bolts, I end up at a point where one usually snaps out and sounds as if the the threading has been stripped. I immediately stopped, and noticed that the threads were not damaged, tried again, and it happened yet again. I'm thinking I should probably grease the bolts, or maybe this thing is messed up. Anyone have any idea as to what is going on?

[DaveM]

If you're tightening a bolt and it suddenly 'snaps' and gets loose, soemthing is definately stripped. I'm guessing you're looking at the threads on the bolt and they look ok. Unfortunately, it is likely the threads in the stem that are stripped.

Bad news is that if this is true, you probably need a new stem. Those bolts are too important to ride with one missing. If the bars slip or break off, you're going to crash hard.

You should probably take it into a shop and have them check it out.

good luck

[cyclerUK]

The headset bolts should really be "torqued" as they can snap if overtightened.

Somewhere on the stem it usually gives the maximum torque the bolts should be done up too. As DaveM says, if it's the internal threads then it means a new stem.

A friend had one of these screws snap last week while out riding. He was on the "hoods" and the bars rotated down. He was very lucky as he was going downhill at the time !!!.

[awmeat]

I think by "snap" you mean that you get to a certain point where the bolt gets pretty tight and then "snaps" when more pressure is applied. If that's the case then take the bolts all the way out grease the threads and also the inside edge of the bolt where it contacts the stem body. What you're probably experiencing is what happens when two different metals such as the aluminum of the stem and the steel of the bolt are put in contact with each other.