double vs. compact double

[VeloVT]

Yay! Shopping for bikes is so much fun.

1. Double vs Compact Double (vs Triple). This refers to the number and ratio of the FRONT chainrings on your bike. A standard double is usually 53/39 (that's the number of teeth on each chainring, respectively). Some bikes have triple chainrings, with an extra-small chainring allowing lower gears for extended or hilly touring. A common ratio for a triple might be 52/42/30. A compact double basically splits the difference, giving you some lower gears than you'd get with a standard double, but without the additional weight/slower shifting of a triple (though I've read mixed reports on the latter count with compacts). A common compact ratio is 50/34.

2. 9sp vs 10sp (or 8sp!). This refers to the number of gears on the REAR cassette on your bike. More gears gives you... well, more gears... but the important thing to remember is that you are not **necessarily** getting more high gears or more low gears in say, a 10sp vs a 9sp, they may simply be more closely spaced. You'll also see the range of gears in the cassette specified -- it will look like 11/23, 12/25, etc, and again refers to the number of teeth on the largest and smallest cogs.

Good luck!