Any cycling jersey that makes your biceps look bigger and your stomach look smaller has a clear edge over the typical sausage casing that passes for a riding top, but Descente’s Optima Ice offers more than just a flattering cut. The road jersey is treated with xylitol, a natural sweetener derived from birch trees and fruit that acts as a phase-change material—it absorbs heat to keep you cooler. Descente claims this technology, which it calls Icefil, can actually reduce surface temperature of the jersey by up to five degrees Fahrenheit.

It sounds nutty, but phase-change materials do work. Outlast is perhaps the best known—it uses micro-capsules of paraffin (essentially, wax) that absorb heat by melting, then release heat back to you by solidifying when external temps drop. The question about xylitol, then, isn’t whether it’s effective in theory but whether it’s effective in the real world.

The answer is, probably. The Optima Ice is the most comfortable jersey I’ve worn in ages, so comfortable I wore it three days in a row and was in no hurry to take it off after the rides. The temperature range was mid-60s to high-70s, and with the sun beating on my back the black-colored jersey did seem cooler than most—and that was my perception before I knew what the jersey was made of. Ideally for testing, though, half the jersey would be treated with xylitol and half wouldn’t and the tester wouldn’t know which was which.

Until a hybrid jersey shows up or the temps climb into the 80s, my conclusion is the xylitol very likely works, but this is such a great jersey it really doesn’t matter. The Optima Ice is comfortable and flattering, and, at $90 ($80 street), it costs about the same as other high-end jerseys. Two open and one zippered pocket stash your Gu, phone, and other essentials. The grippy elastic hem keeps the jersey from riding up on you (though it will do nothing about friends who attempt the same). And the full-length zipper and four mesh panels will do far more to cool you than any phase-change fabric, anyway. Very sweet.

Tagged as: apparel, cycling