Choosing a Shimano DuraAce Cassette for 53 X 39 Chainrings

2011-03-08 • SEND FEEDBACK •
Related: gear, Road Bikes, Shimano

Shimano offers a versatile selection of DuraAce cassettes. But what I really want is a 12 speed cassette, so that I can have a well-spaced 11-30!

The discussion that follows pertains mainly to use with the standard front 53/39 chainrings. Any using a compact double (50/34) will definitely want a cassette that has an 11-tooth rear involved. There are also 53/42, 52/39, 54/42, 55/42 and 56/44 chainrings.

I’ve tried three cassettes on standard 53/39 front chainrings:

• 11-25 (nice on flats, but too limiting when it gets steep).
• 12-27 (best all-around choice).
• 11-28 (not entirely a win compared to 12-27)

My recommendation for all-around best choice for mixed riding is the 12-27, which is what I’ve ridden for years on 53/39 chainrings. Riding an 11-28 is making me notice the middle gap a little more than the slightly easier 28 ring.

The 27 ring provides very good uphill climbing potential, and the 15-tooth gap of the 12-27 provides a spacing that never leaves you looking for that intermediate ring you don’t have, especially in the middle of the cassette. The 12-tooth small ring is just fine for most everyone, almost all the time, so losing the 11-tooth ring is not important.

The big jump from 24 to 28 teeth is more than one would want in the middle of the cassette, but on steep uphills the 28 provides a 3.7% easier gear than 27 teeth— which is a small but noticeable difference.

Aside from the 11/12 and 28/27 difference, rings 2/3/4/5 are identical. But the jump from 15 to 17 teeth instead of 15 to 16 teeth does show up as a difference: it’s right around there that a lot of riding is done.

DuraAce sprocket teeth layout for 12-27 vs 11-28

Note the inflection point from gear 6 to gear 5 with the 11-28 cassette. Since this is a very common gear to ride right in the middle of the cassette, it might or might not feel right. I notice it when I ride the 11-28, and I’m not sure getting that one extra tooth (28 instead of 27 is worth it). I think a 12-28 might be ideal, but it’s not offered.

Gear ratios (39 chainring) with 11-28 and 12-27 cassettes

Cassette choices

All the choices shown below. Only the latest derailleurs can handle the 28-tooth ring.

DuraAce CS-7900 (2011) cassette choices with sprocket teeth combinations