Numpty question but what's the difference between a "road" seatpost and a monutain bike one? Looking at carbon posts and struggling to see why there would be a difference unless mtb ones are way stronger?
You have hit the nail on the head and answered your own question.
yep mtb ones are stronger, Thomson are about the best.
yup, roadie ones will be weaker
but IMO some mtb ones are a bit fimbsy. Bent a EA70 on the first ride out in the Peaks. Swaped it for a titec one and its been faultless. The clamps easier to adjust too.
Road are usually shorter too.
I'd think the size thing would be the big difference, road bikes are nearly all 27.2, with some being 31.6, and probably all quite short. The Easton EC90 layback is one of the few 'road specific' posts I can think of, and I know people using them on MTBs.
If you want a nice *really* light seatpost for a fairly sensible amount of money, for XC riding, I recommend New Ultimate. 135g for a 30.9x350mm.