The SDG I-Beam system isn’t new, but you’ll be seeing a bit more of it in 2012 as several other manufacturers have licensed the design. The seatpost uses a tough single pivoting head and a pair of pinching clamps all working off a single 5mm bolt.
You have to use it with an I-Beam saddle; various models are available, all of which have a single central rail with serrations on the underside. Loosening the seatpost bolt allows you to adjust the tilt of the saddle and slide it fore or aft.
While it doesn’t look like much, it’s actually pretty bombproof – the fact that many downhillers run the system is testament to that. The 350mm-long post can be had in carbon fibre or alloy and with inline or 20mm set back clamps. We chose the alloy inline version which doesn’t weigh much more but costs a lot less.
Conventional saddle design often uses flex in the rails to add a little comfort; there's none of that with the I-Beam system, which results in quite a 'direct' feel. The post does flex slightly though, if you've got enough exposed shaft, which takes the edge off bumps. This feeling is ampliﬁed a little more (adding to the comfort) in the more expensive (and lighter) carbon version.
This article was originally published in What Mountain Bike magazine.