Thomson stem bolts - made of cheese

[p nut]

Anyone else having issues with the new 3mm Thomson bolts? The older 4mm bolts were just fine. But the new ones, I seem to be rounding out the heads. I use a torque wrench and I'm real careful about inserting the key all the way.

Guess I'll be visiting the hardware store for some better bolts.

[dddd]

It sounds like a case of the hex key perhaps being worn, deformed or poorly-sized. The recommended torque shouldn't round out those hex recesses.

Also be sure that your wrench apparatus isn't tilting the bit, that it is applying pure torque and no off-axis forces. Extended-length bits tend to make this problem more pronounced, and it tends to be worse with a shorter wrench, which needs more side force at the handle to generate the same amount of torque. I use a thumb against the head of the torque wrench to balance the side-load at the handle and deliver just torque and no side-load to the bit. Accuracy is not affected.

Bolts from a hardware store? Be sure that the 8.8 or 12.9 original bolts are being replaced by the same grade, with appropriate washers under the heads.
If the original washers are captured on the bolts then specific-sized (ID, OD and thickness) washers might need to be sourced as well.
Perhaps Thomson could help out here, they are a US company so there's that.

[jbreebs]

I had the same problem, did what I could to get them tight and so far they appear to be holding on alright. Not looking forward to removing them, though...

[p nut]

It sounds like a case of the hex key perhaps being worn, deformed or poorly-sized. The recommended torque shouldn't round out those hex recesses.

Also be sure that your wrench apparatus isn't tilting the bit, that it is applying pure torque and no off-axis forces. Extended-length bits tend to make this problem more pronounced, and it tends to be worse with a shorter wrench, which needs more side force at the handle to generate the same amount of torque. I use a thumb against the head of the torque wrench to balance the side-load at the handle and deliver just torque and no side-load to the bit. Accuracy is not affected.

Bolts from a hardware store? Be sure that the 8.8 or 12.9 original bolts are being replaced by the same grade, with appropriate washers under the heads.
If the original washers are captured on the bolts then specific-sized (ID, OD and thickness) washers might need to be sourced as well.
Perhaps Thomson could help out here, they are a US company so there's that.

I believe the allen key is a craftsman. Maybe I'll need to look at something else. Hadn't been a problem thus far.

I don't think the Thomson bolts come with a washer. I just called Thomson and they just shrugged. Didn't even know what grade is specified. Not too helpful.

[DonH]

Its very important to use a sharp allen wrench or bit. Also, all allen wrenches and bits are not created equal - some may be a couple thousanths of an inch bigger and fit better.
Sometimes I grind the chamfer off the tips to get slightly more bite.
That said, I do prefer the 4mm bolts (they are easier to work with for me).

*EDIT - my comments are regarding the X4 stem - I have absolutely no experience with the X2.

[BikeNY]

I haven't had a problem with the new 3mm bolts. I never had a problem with the old ones either though!

My guess is they changed them to reduce the risk of the damaging the threads in the stem. The idea being the bolt heads would get damaged before you could tighten the bolts enough to damage the threads in the stem itself. That's just a guess of course.

I always use a torque wrench and a good bit, no issues so far.

[benb]

They changed them to Swiss cheese to compensate for the faceplates being shoddy and cracking so easily if not perfectly torqued?

Been there, seen it crack. Never again. :eek:

[BikeNY]

They changed them to Swiss cheese to compensate for the faceplates being shoddy and cracking so easily if not perfectly torqued?

Been there, seen it crack. Never again. :eek:

I had one crack on me before I started using a torque wrench. I've also had other manufacturer's faceplates crack before I started using said torque wrench.

I would rather have to replace a couple of bolts than an entire stem, or even a faceplate.

[veloduffer]

Are the bolts titanium? I had a similar problem with a 3TTT stem and had two bolts snap their heads well before I reached the torque level. I replaced them with steel bolts, as it made me nervous that the ti would break on a ride.


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[djg21]

Anyone else having issues with the new 3mm Thomson bolts? The older 4mm bolts were just fine. But the new ones, I seem to be rounding out the heads. I use a torque wrench and I'm real careful about inserting the key all the way.

Guess I'll be visiting the hardware store for some better bolts.

I just keep a couple of extra Thomson bolts in my toolbox just in case. I’ve never had to replace bolts, except once, where one of the bolts on my dedicated trainer bike started to get corroded from sweat. I from time to time regrease them and check the torque after putting some carbon paste on my handlebar.

[pcxmbfj]

If you have 4mm bolts from an older stem they fit.

[cdimattio]

Anyone else having issues with the new 3mm Thomson bolts? The older 4mm bolts were just fine. But the new ones, I seem to be rounding out the heads. I use a torque wrench and I'm real careful about inserting the key all the way.

Guess I'll be visiting the hardware store for some better bolts.

I thought this had been covered before. The 3mm bolts are awful, particularly with the 5.5 nm torque spec. Replacing them with 4mm was my solution.

If you research the common handlebar slippage on the Thomson X2, bolt replacement is also a frequent recommendation.

[p nut]

I thought this had been covered before. The 3mm bolts are awful, particularly with the 5.5 nm torque spec. Replacing them with 4mm was my solution.

If you research the common handlebar slippage on the Thomson X2, bolt replacement is also a frequent recommendation.

I might be doing just that.

Anyone have a good online source for a bag of 4mm bolts? I've got about 4 stems.

[doomridesout]

This entire thread is why I decided never to buy an X2 again... Plenty of light, stiff, good looking stems without these issues.