WannaB wrote:
I raced a few Cyclocross races last fall on and old roadie with some knobby tires. Have since purchased a 2018 Crux with plans to start racing regularly in the fall, as well as start riding some gravel events (when they come back).
Have a 46/36 in the front. In training and riding hills, the 11/28 cassette leaves me feeling a bit under geared.
Am planning to upgrade to a long cage derailleur and swap out the rear cassette. Was planning 11/32, but mechanic suggested might as well go to 11/34.
Is there going to be a big difference? I know more is more. But am thinking the 11/32 should be sufficient?
Since I still plan to race, would I be losing something having the larger spacing at the lower end gears?
Am I overthinking this?
Maybe a bit. You're certainly overthinking the last part. Once you have the right tools, swapping cassettes is a few minute task. If the race course calls for tighter gearing, just swap back to the 11-28. A GS "mid-cage" derailleur (there really aren't SGS "long cage" road derailleurs) will shift an 11-28 just fine, even if the chain is a few links longer than optimal. My bike came with an GS RD and an 11-34 cassette, but it's quite flat locally so I ride with a 12-27 cassette most of the time. I keep that 11-34 handy, though, in the event that I travel someplace hillier. I didn't take any links out of the chain, so going between cassettes requires only a B-screw adjustment and sometimes a fine-tuning of the RD cable tension. Shifting has been just fine on the 12-27.
For cyclocross/gravel, I would recommend a clutched rear derailleur like an Ultegra RX or one of the new GRX, especially if you're going to run an 11-28 with a chain that has enough links for a 11-34. If you were
really doing it right, you'd have a specific chain for each cassette that had the optimal number of links for that cassette. For a couple races a year? I personally wouldn't bother.
As for whether an 11-32 or an 11-34 would be better, it's a tough call. The 11-34 has at least a 2-tooth gap on every step, while the 11-32 has single-tooth gaps for the 4 tallest gears. It comes down to a couple questions. 1st, are you a cadence slave, only comfortable with extended pedaling in a fairly narrow cadence range? 2nd, are you looking to maximize your performance all the time, intent on using the cassette for racing or for hard group rides that are a real challenge for you to keep up with? If the answer to both is "Yes," get the 11-32.
If you can pedal as easily at 65 rpm as 95, or you can just back off a touch without fear of getting dropped by selecting the lower gear when you find yourself "between gears," and you want the lowest gearing possible to extend your capacity to climb, it's the 11-34. Or spring for both, and have 3 cassettes at your disposal to cover a broad variety of situations.
"They're made of latex, not nitroglycerin"