Recently installed a syncros stem and realized that I needed a torx 25 bit to tighten the bolts.
Fortunately, I had the bit, but I needed various adapters to fit the torque wrench.
I went back to the spec, and nothing was mentioned about the torx socket head cap screws.
The next problem is if you are on a long ride or Brevet and need to adjust the handlebar or take up some play in the aheadset. You'll need the torx bit and a lever. To me this seems like a hassle.
Usually, with a couple of allen wrenches you can handle all the bolts on the bike.

Does anyone know a good reason why unusual bolts were used?
Thanks
YannisG

Can't say why they would use Torx but they are harder to strip the heads on and less likely to get removed by thieves. Both of these are really trivial advantages and easy enough to replace with some allen head bolts with no loss of strength or safety.

Quite a few road bike parts use torx bolts now. Also MTB disc brake rotor bolts have used them for years. Multi tools tend to include them as standard now. They are generally harder to strip out when using small bolts, not sure that is the reason though.

Thanks for the response,
I never though of checking my multi tool. It has a #25 torx. So I am good to go. No need to replace them.
YannisG

Not really an issue with stems since they are Al alloy and the threads will strip before the tool interface.

More likely Torx are used to look cool...

On the Ritchey C260 stem, from what I've read, they started using the T20 bolts because the hex bolts they originally used were getting stripped at the head.

I'd be fine if all the bolts on a bike were torx. I don't like that only some are as it just makes on the road repairs more difficult. Not all of my multi tools have them (some are a few years old)..

Shimano now uses T30 Torx chainring bolts on their current cranksets. They are getting more common.

Sounds like cheapo hardware...

Yeah, I have a set of FSA chainring bolts that are Torx, but those make sense because they are aluminum...

Yea, could be, but they are tinier bolts than what you find normally on a stem, which I think was the reason given - that going that small increased the liklihood of stripping with hex, but not torx. But I can't say from experience because the C260 stem I used for a while had Torx. I got rid of the stem because the design almost defeats the purpose of a open face stem and it's a PITA to get bars mounted on. Certainly I didn't need whatever design advantages they were trying to accomplish so wasn't willing to use it. I switched back to a normal WCS stem.