What does Compact crankset mean
|By Per Bausager
FSA are the inventors of the compact cranks. It is an invention which is a ingenious as it is simple. The concept is really an answer to the same need that triple cranks arise, to achieve gearing ratios that enables recreational riders to climb the hardest ascents without "breaking" their legs.
The concept of the compact cranks is to reduce the number of teeth on the chain rings, so e.g. instead of using the traditional 39/53 combination, one uses 34/50. By this one will by e.g. using an 11/25 cog achieve gear ratios that is otherwise only available by using triple cranks. And the bigger gear 50x11 will advance the bike further pr pedal round than the alternative 52x12, as it equals to 53x11,7. The lowest gear in this combination 34x25 refers to 39x29.
There are several advantages with this solution:
1. A much lower weight than with the triple equipment which requires a longer bottom bracket axle, a longer cage, and 3 (bigger) chain rings.
2. The solution can be used on the same bike without changing anything but the cranks.
3. A shorter axle (which means a lower Q-factor, again meaning better transmission of power, better aero dynamics and lower weight)
Additionally Campagnolo also now offers compact cranks and even special front derailleurs for this in the chorus and record groups.