How much layback on the Spesh seatpost? Trying to work out (without actually sitting on one!) if a small would fit me better than the medium. I’ve been riding a medium with a 60mm stem, an inline I-beam post and the saddle slide all the way forward. I figure with the small, possibly 75mm stem, layback post and saddle mounted in the middle I might have about the same reach. Plus there’s a small going on eBay local to me! Thanks.