Jerome Pineau wore the climber's jersey in the 2010 Tour de France thanks in part to Campagnolo's standard 53/39 gearing. But a compact crankset may be a better choice for you.
(Photo: Yuzuru Sunada)
Reader: I ride a regular Tuesday and Thursday shop ride in the Texas hill country. My Colnago Extreme C has standard Campy gearing (53/39) and I use the 12/25 10-speed cassette. My question is: Most of the guys in the front climb in their big ring. I am fit enough to stay with them, but I am not able to maintain their pace without downshifting to the 39. The climbs are not long, but there are a lot of them, and when we hit the tops, I always lag behind while I am shifting gears back to the 53. Some riders say that I should be riding a compact crankset. Would that be more efficient, or would I be losing speed with the smaller 50/34 gearing?
RBA: Although you may be better off conditioning your body to climb in taller gears, in this case, I think you may be better served by a compact crankset. The reasoning is that the switch to a 50-tooth chainring, paired with an 11/25 cassette, offers you a wider range of gearing options in the big chainring. With modern drivetrains all designed to use the extreme crossover gears (big/big and small/small chainring and cassette-cog options), the compact offers a wider range of gearing options — especially for those who prefer to remain in the big chainring.
For instance (and bear with me on the numbers): Shifting to the 25-tooth cassette cog while using the compact’s 50-tooth big ring is a similar gear ratio generated by the standard-crankset’s 39-tooth small chainring paired with a 19- or 20-tooth cassette cog (19.5, actually). That’s a pretty low climbing gear in a fast-paced hill ride. Conversely, the compact drivetrain’s 11-tooth cog paired with the 50-tooth chainring works out to a slightly higher (faster) gear ratio than your Campy’s 12x53 generates. The Campy standard is 4.4166 to 1 and the compact is 4.545 to 1. The bottom line is that using compact gearing will give you the slightly lower climbing gear your body prefers, while remaining in the large chainring and shifting in even steps, using the right shifter. You would no longer get dropped while forcing that big upshift at the top of each climb.
It is interesting to note is that tests carried out by Shimano and independent researchers in Utah determined that there is a significant reduction in friction when the driver and driven sprockets are larger in diameter. The implied benefit of climbing in the big ring is that you are using larger cassette cogs and thus reducing the friction created by forcing the chain around a smaller sprocket in high torque situations. The research implies that climbers may be better off with compact gearing, because they will be optimizing their power with large cassette cogs—and that time trialists would be better served by chainrings in excess of 53 teeth because they would be turning the larger cogs in the center of the cassette instead of the inefficient 11- and 12-tooth cogs that are employed most often today.
FSA's 50/34 Gossamer compact crankset. |