Snapped Bolt

[HLaB]

I was fitting a new stem last night and one of the 4 bolts (in this case) that attaches the front plate of the stem, the bit that goes round the bars snapped/ the head came off. BTW I've never had a bolt snap before. The handle bars seem secure enough is this something that'll:
a) wait I can cycle the bike up at next oppurtunity to lbs to have it corrected.
:?: is dangerous/ shouldn't cycle with and I'll need to put it in the back of a car.
c) nothing really to bother about, the other three bolts are holding it fine and secure. For cosmetic purposes I would want to get it sorted but its no biggie.
d) something else that I have thought about.

Cheers again

 

[mickle]

Very unusual, I've never seen a stem bolt fail. I wouldn't ride it, if the bolts are faulty another could go the next time you hoik on the bars.

Either it's a warranty issue or you've over tightened the bolts.

 

[GilesM]

Personally I wouldn't ride it ride now, although I am sure that three bolts could hold the bars in place okay, it is designed to have four bolts, I expect it snapped because you tightened it a bit too much (very easy to do), if it's an Aluminium stem it will have aluminium bolts and they really do not need to be tightened very much, most of the Stem makers recommend the required torque which will be low around 6Nm. My concern would be that the other bolts could also be too tight and hence they have a chance of shearing when you ride it. For safety reasons I would suggest taking it by car to your LBS, it might be sensible to ask your LBS to replace all four bolts, just in case they have been over stressed . If you happen to be anywhere near East Lothian shout, and I could give you a hand.

IHTH

Giles

 

[mickle]

if it's an Aluminium stem it will have aluminium bolts

No it won't, there isn't and never has been a stem on the market with aluminum bolts. Steel or maybe Ti.

 

[GilesM]

No it won't, there isn't and never has been a stem on the market with aluminum bolts. Steel or maybe Ti.

I'm happy to be corrected, but I fitted a Hope Stem about a year ago, the bolts definately were not Ti, but they seemed to be too light for steel.

I could well be wrong, but it doesn't alter the fact that the torque settings for tightening these bolts is very low.

 

[yenrod]

Bolts are available in halfords - something they are usefull for ! finding bolt fastener shops is quite difficult !

 

[gbb]

For a bolt head to snap before the alloy stem stripped infers a definate weakness / failure of the bolt. Sounds obvious, but steel is usually MUCH stronger than alloy. A stripped thread would usually be the first outcome.

It really does sound like a defective bolt. Good grounds to have it sorted under warranty.

 

[HLaB]

I popped to the lbs at lunch time, they said it shouldn't happen either, just bring it in and they'll sort it. Its a bit of a pain I've got to put the bike in the car and drive there though, there's something ironic about driving a bike to a bikeshop thats only 5 miles away. I might do it tonight, they're open till 7 or then again I might not bother with the rush hour traffic and leave it til the weekend.

 

[Scoosh]

Could you not just remove the stem completely, use one of the other bikes from your stable, put the stem in your pocket and cycle it in ?

 

[LLB]

For a bolt head to snap before the alloy stem stripped infers a definate weakness / failure of the bolt. Sounds obvious, but steel is usually MUCH stronger than alloy. A stripped thread would usually be the first outcome.

It really does sound like a defective bolt. Good grounds to have it sorted under warranty.

This would depend on whether the stem has been helicoiled to increase the strength of the tapped hole - common practice on ally components in the aerospace subcontractors where I used to work.

 

[02GF74]

I wold be very surprised if it is an aluminium bolt. Of the stems I have seen, they use 12.8 steel allen head bolts -these are strogner than the usual 8.8 bolts.

you would have to really tighten it up for the head to ping off and the thread would have stripped. I have yet to see a stem with helicoil or some other inseert fitted.

Undoing the other 3 bolts and assuming the front plate comes off, the broken bolt would be sitting in the stem and sould be undone with pliers or by sawing a slot and undoing it with a screwdriver - it shouldn't be in tight

 

[GilesM]

My mistake, I checked, the bolts are all steel in the Stems on my bikes, thinking about it, Aluminium would be a bit dumb. Makes it even more of a surprise that the bolt snapped, just good to hear that HLab's LBS was happy to sort it all out.

Giles

 

[HLaB]

Could you not just remove the stem completely, use one of the other bikes from your stable, put the stem in your pocket and cycle it in ?

I thought it was jammed but I was wrong done exactly that Got the new stem sitting in front of me maybe I'll get round to fitting it and hopefully the bolts don't snap this time.

 

[LLB]

I wold be very surprised if it is an aluminium bolt. Of the stems I have seen, they use 12.8 steel allen head bolts -these are strogner than the usual 8.8 bolts.

you would have to really tighten it up for the head to ping off and the thread would have stripped. I have yet to see a stem with helicoil or some other inseert fitted.

Undoing the other 3 bolts and assuming the front plate comes off, the broken bolt would be sitting in the stem and sould be undone with pliers or by sawing a slot and undoing it with a screwdriver - it shouldn't be in tight

You would do if I made them for a living