I'm planning on doing the C2C this summer on my singlespeed jump bike with the missus, but as its a small (14") frame with a low BB, ordinary length seatposts aren't long enough to put my legs in a sensible position. It's a 30.8mm (nice and awkward) diameter I'm needing, but I've got a 27.2mm shim to hand, but I'm thinking with a long post, the larger diameter will be lot less stressful on the bike.

I've done a look around, and so far I've only found the Thomson Elite 30.8 x 430mm (£66.95 at wiggle), and the Roox S4 XL in 430mm x 27.2mm (£39.99 at billys.co.uk).

I also have to buy a saddle to match because at the moment I'm running the Macneil seat and post combo for "proper" riding :D. Because of that, the Thomson is a wee bit expensive for me, and I'd be a lot happier with the Roox if it came in a bigger diameter (it comes in 30.9mm unfortunately).

Hope one of you can help

Cheers.

you could buy a TiTec Telescopic post and just use the Lower part of this as the upper tube is 27.2 well it is on mine.

That'd give you a nice extension.

p.s. your mad C2C on a SS jump bike LOL

Apologies if this sounds stupid, but I don't see how this will help? It says it goes up to 410 mm max.

Just use the Lower, with your existing 27.2mm seat post, you could add @150mm's maybe 170mm's onto your existing post.

Don't worry about the strength reduced with Shims it doesn't really matter and your bike was built strong to jump so the frame will be fine.

Pretty sure my bike is a 30.8 and I've literally put a 27.2mm post into it to test a Suss Post while waiting for a shim.

your seat should still work, if you using the same seat post to :) double result :)

After some faffing and guesstimation, I think 430mm should be enough for my needs - just have to see if I can find something a little cheaper first...