- How to get rounded bolt out of a Thompson stem?
Like an idiot I’ve rounded one of the steerer bolts in a Thompson stem.
I’ve tried torx bit- to big or to small, no purchase.
I’ve tried a different size allan key, no purchase.
Next option (s)
Cut a slot. this will involve cutting a signigificant amount of stem- difficult and unlikley to work as the bolt head is so small.
Drill it out. Last time I tried to drill an steel bolt out of alloy, i made a right hash of it.
Cut the bolt through the gap? Might lead to damage to the fork steerer.
Take it to the bike shop.
Any better suggestions? Its soaking in wd40 nowPosted 1 month ago
Thanks for the suggestions!
I’ll clamp up the other bolt, try and get it in the vice and drill it with a fresh bit. Then drill from the other side.
I can’t get anything to catch as it is now.
I’ve got a set of bolt extractors from my last adventures in drilling a stripped bolt out of a crank.
I’ve mentally written the stem off. So if it’s ok, That’s a bonus.
Photos tomorrow 😀Posted 1 month ago
When i say impact driver i mean something like this one, not a battery or air powered tool btw.Posted 1 month ago
I had the same recently, also in a Thomson stem.
Didn’t think about tightening the other bolt and easy outs didn’t work.
Ended up cutting it with a dremal through the gap. Very easy to do and causes no damage to the stem of your careful, but beware of the tension it is under.
The bolt head went with such a force that it made quite a clatter as it hit the garage door – wouldn’t want to be in its path.
Still leaves half a bolt on the thread which I haven’t yet got out as the stem is only used on an indoor trainer so 1 bolt will suffice.Posted 1 month ago
I used a dremmel to cut the top bolt.
It went with a bit of a ping!
Ran out of garage time to drill the other half of the bolt out.
I’ve gouged the gap between the two sides of the stem slightly. Perhaps doubling the size of the gap.
Would you ride a stem like that? This is assuming I can get the other half out.
MartinPosted 1 month ago
The problem was caused by a slightly under sized hex key on the multi top that lives on my bike. Used that,felt the bolt go a bit.
When I got home and tried a park tool one it rounded completely. The same park tool one has now twisted getting the other bolt out. 🙄Posted 1 month ago
Worth loosening and retorquing your other bolts I’d suggest to prevent a recurrence.
Oh and I’d probably use the stem but get a new one for Christmas or birthday!
My mate has a habit of putting a ‘farmer’s nip’ on all his bolts, thus ensuring they are impossible to remove again!Posted 1 month agokerleyMember
I still find them very delicate (using a torque wrench with decent allen key head).
And all very well designing them to round if over torqued but how do Thomson then expect the ham fisted person to get the rounded bolt out. Other stems don’t resort to silly little sizes do they?
I like Thomson stems and have one on my bike but the bolts are a pain.Posted 1 month agotrail_ratMember
A few reasons:
1. We think they look nicer.
2. Serrations have been removed to lessen corrosion.
3. Most importantly, the Allen socket has been dropped from 4 to 3mm. This will act as a torque limiter as in most cases you cannot get the bolts tighter than 55 inch pounds. The 4mm socket bolts could get as high as 150 inch pounds. This should help riders without torque This should help riders without torque wrenches avoid damage to stem, bar and steerer.
55in-lbs is 6.2nm – the spec for the x4 is 4nm and the x2 is 5.1
people were overtightening them and splitting the faceplace across the middle – as folks still do with hope stems.Posted 1 month agoTiRedMember
I found the bolts to be as soft as cheese and rounded too easily. That’s using a torque wrench. And every time I hit a pothole, my Ritchey bars would rotate. I eventually binned a 120mm stem for this reason. Still have a 110 mm stem on another bike, but I haven’t needed to adjust that.
They also scratch more easily than any other stem I own (and I own over 25).
Ritchey also spec small bolts on some of their high end carbon stems. I have yet to round one of those bolts.Posted 1 month agosimons_nicolai-ukMember
Bolts are soft as cheese and rounded too easily, even used with a torque wrench. for the remaining bit of bolt you try pushing it out from the other side with a small screwdriver – it should turn easily now (that’s how we got the rest of the bolt out of katie’s stem)
Issue we were having before is that the lower torque they’re speccing wasn’t enough to keep the stem straight – even a very minor low speed off would turn the stem on the steerer. All very well using a torque wrench in the workshop but it’s not going to happen at the trailsidePosted 1 month ago
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