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I have a 2015 Specialized Roubaix SL4 Disc with a CG-R seatpost, and recently bought a Fizik Vento Argo R1 short-nose saddle for it.
Knowing it has ovalised carbon rails and not the standard 7 mm alloy rails, I ordered a different clamp for 7x9mm rails. I was dismayed to discover, however, that the Vento Argo R1 actually has 7x10mm rails.
Will this work? Is it safe? Is there another clamp I can put on a CG-R seat-post which is specifically meant for the rails on the Fizik saddle?
I’m going to attempt an answer since someone else had this problem.
Some seatposts clamp the rails from the top and bottom. If you know what a Thomson seatpost looks like, those are to to bottom. Some seatposts clamp the rails from the sides. The CG-R is one of those.
Carbon rails are ovalized, with 9 or 10mm being the vertical dimension. Clamps that go top down should be fine with either height. I am assuming the heights are actually different. Given the 1mm difference in nominal dimensions, I would assume this is the case. Note, however, that everyone uses the 31.8mm handlebar clamp standard, but Deda (at one point?) reported their diameter as 31.7mm. I think the actual dimension may have been 31.75mm nominal, but most people rounded up.
I would assume that rails clamping from the side need to explicitly state compatibility with 9mm or 10mm rails. So, if I were in the OP’s position, I would consider using a different seatpost, not that there are a whole lot of direct alternatives to the CG-R. The Canyon VLCS seatpost has a similar aim to the CG-R, but it’s been reported as out of stock for a long time.
