Fizik saddle carbon rails vs K:ium rails - are they the same size?

Triathlon Forum
1

I thought I read somewhere they were slightly different sizes but cannot find anything other than a weight weenies forum post about some not fitting all seat-posts.

I’m not specifically looking for carbon rails but there’s some saddles on Ebay that are the color I want that are priced well.

Anyone have experience with the carbon rail versions?

2

Says right on their website that carbon is 7x9mm. Kium is round. Doesn’t matter if you have a vertical clamp but if your clamp goes on from the sides, then you need a specific 7x9 shaped clamp

3

Thanks so much for finding that for me.

4

The Kium rails are 7mm round. The carbon are are 7x9, with the 9 being vertical. A saddle clamp that presses vertically instead of laterally will work fine. I rode Fizik carbon-railed saddles for more than five years with vertical saddle clamps on 3 different bikes.

5

Not to derail the thread, but if you have a specific 9x7mm lateral clamp, will it work with 7mm round tubing?

6

No. The rail would have 2mm vertical play and potentially ruin the clamp if you torque down on it enough to hold the seat in place

7

Thanks
.

8

This is just a PSA about carbon rail saddles and a 2015 Cervelo P2 and I assume P3 seatpost compatibility

I had a hard time finding anything about the seatpost on my P2 and its compatibility with carbon rails, maybe my google skills are going away but I finally found these so I can use a carbon rail saddle:

https://www.treefortbikes.com/Ritchey-Carbon-1-bolt-Seatpost-Clamp-Kit

This is the clamp kit you need. Choose 7X9.6mm