24 June 2008

bikefix Exclusive Review: USE Sumo Carbon seatpost

I originally posted my review of USE's Sumo Carbon seatpost last December. As Maverick owners, Charlie and I have relatively few options for seatposts (due to the reclined seat tube)- of which the Sumo is one. Charlie has decided to throw his two cents in as well. Read on...

I have been using the USE Sumo post for a while now. I started using it because my Maverick ML7/5 had such a relaxed seat-tube angle that many posts' heads couldn’t tilt far enough forward to provide a comfortable saddle angle. This is not a problem for the Sumo though; it can accommodate pretty much any bike’s seat angle with its rotating head design.

If you’re thinking of the old USE alien head design, this is not it, nor is it flimsy and temperamental like that post could be. The Sumo uses a single circular machined ring that is then bonded to the carbon post. The two drum-like caps with groves for a seat-rail are clamped against the ring. The clamping is done by one bolt which threads through two small pieces of aluminum, also with rail grooves. As the bolt tightens, the metal drums compress against the ring and the friction holds it in place. It is very simple and it works quite well.

The carbon Sumo is light- 185g in the 400mm length (compared to a Thompson Elite's 228g at 33omm), and is also very tough. I have been riding it for about a year with no damage despite some truly nasty riding from Moab to Colorado to my home state of New Mexico. The Sumo is also made in Aluminum, and Titanium (for road), but the headpiece is the same aluminum design regardless of the shaft material.

I use this post on two different bikes and I really like it. Besides being light and tough, it is simple to adjust. It remained trouble-free for almost 8 months. It’s not a perfect system though. Some seat-rails seem to fit better than others. I had one saddle that wasn’t even close to fitting; it made me wish that there was a industry standard for the saddle rail dimensions.

The only real problem have I had was with the head-clamp rotating backwards after “G-outs” and similar hits of body on saddle. Admittedly, I ran this post for more than half a year without this problem, and it only showed up after I changed saddles and had to use some Moly-Dry Film lube to get the drum shaped pieces to release their hold on the center piece. I then cleaned the head with alcohol but it seems that I messed it up somehow. I took it off, cleaned it out again, and it still moved occasionally. I finally tried to use some carbon assembly compound to add friction, but this made no difference. I then called Ibex Sports (the US USE importer) and they said I could exceed the torque rating etched on the headpiece by a bit. This seems to have solved the problem, but I can’t be sure because (it was only infrequent to begin with) only the most technical trails seem to bump me around enough to cause it. Ibex Sports also mentioned that it is possible to “wallow-out” the drum-like pieces and I may need to replace them. I will try that if it happens again, but so far so good. Keep in mind that this whole issue may be my fault (but it was hard to get those damn drum pieces off).

The carbon Sumo is available in 4 different diameters: 27.2, 30.9, 31.6, 34.9. It has a natural 10mm layback and retails for $140.00 to $150.00 depending on the length.




1 comment:

Timothy Takemoto said...

I have mine on a road bike in an attempt to bring the saddle forward to a more "agressive" triathlon position. I have the saddle as far forward as they can go on the rails too.

And even without G-outs I find that the saddle will move. That dos not mean it is bad. But I think that in an offroad situation the friction between those cups and the post are not going to hold the saddle still, unless perhaps you use some glue.