Cracked stem.

Surprised this has happened, I went to use the bike and the handlebar was loose so tightened it. When I returned home after my ride I noticed this had happened, must have been a hairline crack prior to tightening back up. I think it’s machined from a billet of alu??

U sure its not a sticker?

This is when Thomson asked what you torqued the bolts up to….

Looks like the rhs in the pic has been cracked for a while. But yes looks like you’ve overtightened the faceplate bolts.

No idea how much I torqued them up, but I don’t hang off my allen keys.

Time to buy a nice shiny blue, silver or red one! 8)

No waaaaay am I sticking ano blue on my bike

Anywhere I can buy this part without all the bolts etc, as £20 is a bit steep compared to the X2 that’s £6.

I had a thomson stem that started to go in exactly the same way yours has but I noticed mine when it was just hairline cracks at each side.

time for a new one – http://www.i-ride.co.uk/Thomson-SM-H007-X4-Stem-FaceplateClamp-318mm.aspx

Thomson regard face plates as consumables that should be replaced eventually and I agree with that and like the way they don’t charge the earth for replacements. It’s a shame other makes don’t but then Thomson stems are a bit unique in that other designs come and go but thomsons stay popular and hold their price. I’m not convinced on CNC over forging for stems but cracks are rare and i’m sure they know what they are doing. They only charge something like £6.99 for a new faceplate anyway which reflects there attitude that they should be replaced.

Could have been done up to tight or unevenly but another reason could be your bar diameter is slightly out of tolerance. And yes the dirtiness of the crack face on the right of the picture suggests it’s been cracked a while.

I’d just buy a new faceplate and be thankful it didn’t completely fail on a downhill bit leaving you flying forward holding the bars.

Aye, Thomson call it a consumable and make replacements easy to replace. But since 9/10ths of all the stems I’ve seen crack were Thomson, other companies don’t seem to agree…

I’m sure you know this already, but

Stem bolts must be tightened in this sequence. I would go around 3 times, slowly building up to the correct torque. If you’re being extra careful, I’d ask what [if any] lube or paste to use on the threads too.

I heard thompsons are too old school for the wide style handlebars around today, they can’t hack it

Those hex slots in the capheads have seen a bit more than 5Nm. 😉

The tightening torque for Thomson x4 faceplate bolts is just 4Nm which is surprisingly little and easily exceeded. I’ve seen images of Thomson seatposts snapping just below the head due to overtightened bolts; Thomson kit isn’t indestructible.

PJay – Member
The tightening torque for Thomson x4 faceplate bolts is just 4Nm which is surprisingly little and easily exceeded. I’ve seen images of Thomson seatposts snapping just below the head due to overtightened bolts; Thomson kit isn’t indestructible.

Probably is if you use the right torques then 😉

FWIW I had an Elite stem for a little while, it didn’t hold the bars with only the recommended setting, they never ended a ride pointing in the same direction they started (on an Easton alu bar I think so quite smooth in the middle, but still) It was too long for me anyway so I replaced it with a much less pretty, but lighter and cheaper, Pro stem which asked fortwice as much torque and is still going strong.

they do seem rather distorted.