As Dr Hutch once remarked, no one ever suffered from slipping seatposts until torque wrenches were invented.

They just specced silly small bolts, that’s all.

They didnt even spec silly small bolts – just 3mm Allen heads on a bolt that everyone else puts 4mm heads on. Nothing to stop you swapping them for normal bolts except Thomson Warranty (but how would they know???)

Counter intuitively, if you have a stuck bolt, you can often release it by tightening it slightly before immediately undoing it.

Sometimes you just need to break the grip, and if it wont go one way it might go the other then whip it out.

It does sound like Thompson’s gear is a bit suspect though!

drill it out from the back side rather than the head side. 9 times out of ten the drill will jam and that will free the bolt and spin it out.

So with a bit of trial and error I’ve got the bolt out.

Drilling from the back the bolt spun and caught. It spun halfway and stuck.

I cut it in half again and drilled the last 1/4 out.

I think it will be fine. It’s missing a mm or so from cutting the bolt out.

I’ve replaced the offending bolt with a Thomson one, copper slipped all the bolts and done the bolts up with a torque wrench.

I’ve got a thompson stem on my road bike and that’s been absolutely fine. Hopefully this one will go back to being the same.

Cheers again for the help 😀

As mentioned cut through the gap..then drill from the stud side(NOT HEAD SIDE..this is under tension on the bike wont go through right..) then undersized drill the file out remnants if neccisary only if it doesn’t unwind with a extractor..clean threads copper slip/grease new (4mm!!) Allen bolt or better a t20/25 then that almost certainly wont round out even when stuck..also try bashing it with a soft hammer(breaks the bolt thread tension a bit)..

As mentioned cut through the gap..then drill from the stud side(NOT HEAD SIDE..this is under tension on the bike wont go through right..) then undersized drill the file out remnants if neccisary only if it doesn’t unwind with a extractor..

Username checks out.

I know what to do and I’m having a hard time following that.