I have a 10 speed Cervelo P2 (the OG!) with 50/34 chain rings and have been riding a 12/25 Ultegra cassette on various wheels for years. I’m about 77kg on race day and have an FTP of about 240. Thinking about what cassette would be ideal for these hilly courses next year. Any suggestions? Stick with 12/25, or maybe go for 11/28? Thanks!!
I used 11-28 for 2019 IMLP 70.3. The elevation gain is real.
28 if you like doing long climbs seated
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Would 11-28 be useful on a flat course like IM Florida / 70.3 Gulf Coast too since it’s 11 rather 12? I just did 70.3 GC this year in 12-25 (10sp.) Or might the wider range of 11-28 in 10 speed (bigger jump from one gear to the next one) be a downside on a flatter course? Flatter courses tend to get more wind so that’s another factor increasing resistance.
The climbs at Placid aren’t generally steep. I used 36/25 without drama for both of those races this year. If you’re nervous then 34/28 would give you plenty of room.
You won’t want a 28 on a flat course and might miss a 16. The 12 will net you 30 mph at 90 rpm, 11 is 33 mph.
You could also swap to a larger chainring like a 52 if that would help.
With a 50, you might be fine with 11-23 on a flat course. Given the cost of those events, I’d be inclined to swap to an optimal gear for the course, 10 speed stuff is cheap.
To answer your original question, IMLP with 50/34 and 12/25 cassette will work just fine. I have 10-speed on the same compact crank and same size cassette, have ridden that course 5 times and don’t recall ever needing more gears even on the “3 Bears” climbs. For reference, I am 70kg and FTP about 230.
@Kid
I have a 10 speed Cervelo P2 (the OG!) with 50/34 chain rings and have been riding a 12/25 Ultegra cassette on various wheels for years. I’m about 77kg on race day and have an FTP of about 240. Thinking about what cassette would be ideal for these hilly courses next year. Any suggestions? Stick with 12/25, or maybe go for 11/28? Thanks!!
You and I are very close in gear, FTP, and weight. 2011 P2. I just did Chattanooga full with the 50/34 12/25 combo.
Iwith 50/34 chain rings and have been riding a 12/25
I can’t speak for placid.
Choo 70.3 isn’t a hard course, at all. Just under 1900 ft of climbing and only 1 real climb that is short. The shitty road surface is a bigger factor imo. (fwiw I rode 2:19 on 216w this past year)
If you stick with the 50/34 I think you’ll want to get a cassette that has more mid gears, maybe a 12/23.
What I would probably do is find a 52/36 crankset to put on if I wanted to stick with the 12/25. That will give you a bit bigger gearing up front and still allow you to be a billy goat when climbing.
"The shitty road surface is a bigger factor imo. "
What is your recommendation/strategy for that factor?
To the OP - I have done both races - you are both a little bigger and a little stronger than me. At LP (x4) I have had 36 and 39 chainrings w/ 11-25 in back and no problems. At Choo (x3) your setup will not be an issue.
What you want is a big range of gears for hilly courses. Everyone is too focused on the uphill part of the course. There is just as much downhill as there is uphill. I’ve raced IMLP I think 5 times and always spun out in 54X11. You can lose a lot time going too slow on the long descents and you don’t want a cadence of 120 when racing long course.
Biff
Castelli Multisport Team