Clamping down- bad mix of post and saddle?

[Robbos]

I've just installed this Specialized Power Expert with ti rails on my vintage USE seatpost. Anyone think there's an issue with clamping forces on hollow ti rails? Bonus points for those with actual experience with this set-up/issue
Thanks!
PS- Specialized says I should size down to the 143, but this 155 feels mighty comfy, cannot wait until it's warmer for me to test it out!

[pdonk]

Not the exact same setup, but with a similar design (vintage syncros seatpost) and ti rails (turbomatic 2 with ti rails, another saddle with ti rails I can't remember), I had rails crack due to the bottom cradle creating notches in the rails.

This was before the use of torque wrenches was common, and I likely tightened the clamps down too tight. I would tighten the bolts as loose as possible, but tight enough to keep things in place. That is a big advantage to this design, things only need to be tight enough to offset the force from the other bolt.

[.RJ]

I would be worried about all the hard edges on that clamp

[osbk67]

I’ve used a PMP Italian seat post with a very similar lower cage together with a Selle Italia Flite Max with titanium rails (I think they’re hollow, but not certain) off and on over about eight years and perhaps 12000-15000km in total.

No issues to date. I’m c. 83kg. All road usage.

[dddd]

I had constant slipping issues with my old USE seatpost using a ti-railed saddle.

The bending forces on the rails also meant that the saddle top angle changed a lot as I tightened the tiny clamping screw, making saddle leveling with titanium saddle rails a nightmare.

I'm assuming that current USE seatposts use a more-evolved saddle clamping design than mine from 2008 or so. Mine is very different than yours, having two lower cradle pieces that get squeezed together F/R to achieve tightening. The even older ones with two super-tiny screws going through the lower cradles are even harder to adjust and the screw heads tend to round out. But I think yours is yet quite a bit older!

[Robbos]

Originally Posted by dddd

I had constant slipping issues with my old USE seatpost using a ti-railed saddle.

The bending forces on the rails also meant that the saddle top angle changed a lot as I tightened the tiny clamping screw, making saddle leveling with titanium saddle rails a nightmare.

I'm assuming that current USE seatposts use a more-evolved saddle clamping design than mine from 2008 or so. Mine is very different than yours, having two lower cradle pieces that get squeezed together F/R to achieve tightening. The even older ones with two super-tiny screws going through the lower cradles are even harder to adjust and the screw heads tend to round out. But I think yours is yet quite a bit older!

I think you are talking about the USE Alien seatpost clamp. They're notoriously awful, I've one on a USE seatpost and it does not work well at all. Disappointing from USE as I think most of their stuff is really nice. My suspension post from them is much older and still works great, and their new suspension stem looks great. Yes, mine is super old, probably mid to late nineties. There are newer, better posts out there but it's light and simple!