16 April 2009

bikefix Quickie Review: Race Face Evolve XC seatpost

The seatpost is an under-appreciated component. While building a tube that will support the rider's weight isn't particularly difficult, it turns out that mating that tube to a pair of saddle rails in a lightweight, adjustable manner is pretty difficult. For ages, the serrated cradle did the job without complaint. With the advent of mountain bikes, however, the weakness of a single highly leveraged bolt and a handful of aluminum serrations became clear and alternative designs emerged. Two-bolt setups (such as those from USE and Thompson are lighter and stronger than single-bolts and more easily adjusted, but incorporating the offset that may riders require is difficult and their adjustability can be difficult with folding trailside tools.

When I first saw Race Face's unnamed seatpost design, I was surprised than no one had thought of it earlier. A pivot at the top of the seatpost is attached to a supportive 35mm long rail cradle, to which the saddle is attached with two clamps. Downward forces are supported by the cradle itself and not the bolt, which should greatly reduce the likelihood of bolt failure. At the rear of the clamp is a second pivot, to which a dogbone is attached. The dogbone runs in turn to a band around the post itself. Sliding the band up and down the post provides angular adjustment and a second bolt holds that adjustment.

At $55, the Evolve XC is the less expensive of two RaceFace mountain seatposts using this design (there are three roadgoing versions). It is available in three common diameters (27.2, 30.9 & 31.6mm) and one odd one (30.0mm) and reasonably light at 265g. That's about 30g less than competitively-priced models though 30g heavier than the offroad benchmark Thompson Elite (which runs about $40 more).

For an OEM or replacement-level seatpost, the Evolve XC does a great job. The clamp is easy to adjust and the independant angle and fore-aft adjustments make getting the saddle just so an easy task. With just six weeks on the Race Face I do wonder about the pivots' potential for slop or squeaks over time- though nothing I've seen so far indicates that this will be a problem. Charlie has been using the carbon fiber Next SL version for a few months and hasn't had any problems yet. The design is unique and has quite a bit to recommend it. For the price, the Evolve XC looks to be a sturdily-built, well thought-out option, particularly for those who can take advantage of its 1/2in of setback.



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