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jeffgre's picture
Joined: Mar 22 2010
Posts: 177
Gearing selection for Hilly Ironman

Hi everyone,

I'm trying to plan ahead for Ironman Mont-Tremblant in August and I've been thinking a lot recently about changing my cassette to something more "hill friendly". I know many of you have done IMLP, IMCA, IMSG, and IMCDA. What gearing did you use? Did you wish you had more? Looking at the bike profile, most of the hills seem to be in the 4-7% range, though I see 1 section at 12%.

So far I've found that, if I ask 5 people, i'll get 5 different answers.

Currently I have compact cranks(50-34) up front, and 11-23 on the back, and my fitness is at about a 6hr bike split(+/- 15 min), on a flat course.

I've seen mentions of going anywhere from 11-25 all the way up to 11-28.
- Is 11-25 enough gears?
- Is 11-28 too many gears?
- Something in the middle?

Thanks,
--Jeff

dkhartung's picture
Joined: Jan 7 2009
Posts: 1175
12-27. Rationale: If you

12-27.
Rationale: If you are going downhill so fast that you're spinning out and "need" the 11, then you should probably be coasting and saving energy anyway. And if you need more than a 27 on the back with a compact crank, then you're gonna have problems on the climb anyway.

TriSooner's picture
Joined: Dec 20 2007
Posts: 3376
dkhartung

[quote=dkhartung]12-27.
Rationale: If you are going downhill so fast that you're spinning out and "need" the 11, then you should probably be coasting and saving energy anyway. And if you need more than a 27 on the back with a compact crank, then you're gonna have problems on the climb anyway.[/quote]

That's pretty much it. 12-27. Or put another way, on a hilly course with 26.2 to come, you can never have too many granny gears.

jarhead's picture
Joined: Jun 23 2009
Posts: 1113
the above sounds right. I'm

the above sounds right. I'm in pretty good bike shape, but when I climbed mt. lemon in Tucson, AZ last month (9K ft @25 miles) I was using 11-25 (avg. grade 3-6%) with a compact, all the way up and was in the 23-25 most all of the time. At times I wish I had one more gear so I didn't have to work so hard. at gear 25 I was humming around 215 watts, easy (HIM are 240) but when your going 7-8 min / mile 215 watts seems very very hard.

Definitely loose the 11, seeing that your not a 5 hour guy, you will never be in that gear anyways.

jeffgre's picture
Joined: Mar 22 2010
Posts: 177
Thanks for the advice guys.

Thanks for the advice guys. I'm definitely not a 5 a hour guy, and can't say for sure that I've ever used the 11. I hadn't thought of the 12-27 though. The 11-28 seems like such a huge range of gears. I was afraid I would be giving up too many gears in the middle(that I always use), just so I could have gears 11,28(that I might use).

Boo
Boo's picture
Joined: Jun 12 2010
Posts: 79
Compact with 12-27 for sure!

Compact with 12-27 for sure! 11-28 costs you a key increment around the 23 miles p/h (36kmph) mark when on a compact crank. If you can't go 34-27, you'll struggle anyway as prior mentioned. Even a 12-25 cassette would work well with a compact. I'm on a compact with an 11-28 due to the hills I train and ride through at the moment. Great for long climbs with double digit gradients.

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