Stem screws came loose when riding

[tdm]

So this morning I was going downhill on my road bike and I hit a (small) pothole. I heard a loud crack and looked down to find that my handlebars were loose against the stem. After I finally managed to stop and not crash into anything I noticed that one of the bolts which held the stem face plate on had come loose, and it turns part of the threading inside the stem itself had ripped off and came out with the bolt so it wouldn't fully tighten. Managed to swap some washers around so there was enough thread to reasonably tighten the handlebars down and get home.

I've got a spare stem which I'm going to replace it with but it was a rather scary experience which I don't care to repeat - has this happened to anyone else? Is it a problem associated with 2 bolt stems?

 

[fossyant]

I have had my bolts loosen and this is on Ritchey Pro Stem with Ritchey WCS bars, so not cheap stuff. Not had them de-thread (that's a fitting issue) but had them work loose, so a pot hole has caused them to rotate slightly. That said I have been careful with torque on the modern stuff. The old stuff is fit and forget. You just need to check bolt tightness once in a while.

Was it a cheap stem over tightened. On quality stuff, you need to worry about over tightening, as this can damage the clamped part, difficult to thread a bolt, unless you are ham fisted.

 

[Biker Joe]

Definitely a scary experience.
In over 50 yrs of cycling I have never experienced anything like that.
I don't know if I have been lucky or what.
I've heard of it happening but, so far, not to me. (Touch wood).
I have always been pretty particular about keeping bolts etc. tightened up. Perhaps that's the reason.
I hope you don't have to experience it again.
Take care.

 

[accountantpete]

Sounds like a fault in the metal - which happens very ocasionally.

I have always used 4 Bolt stems. Use 242 Loctite or similar and tighten up carefully.

 

[4F]

Don't get that problem with a quill stem, old school rocks :>)

 

[andrew_s]

It happened to me once, but it was the face plate cracking in half rather than a bolt stripping.