11-23 vs 12-25 vs 12-27

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2007-11-10 5:10 PM

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Veteran
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Surf City USA Huntington Beach, Calif.
Subject: 11-23 vs 12-25 vs 12-27
I know that rear cassettes is a personally issue but I would like some feeback from some veterans if you have time.

I will be competing in an event next June that has a significant grade for a distance. I want to get thru the bike with some of my legs left. I am not too concerned about my time as long as I am under the cut off.

My current set up is 11-23 with 172.5-53/39 on a Felt S22 Tri bike. It fits me like a glove until I start to climb significantly. I am not fond of hills but I know they are a must. On steeper grades I have to drop to my lowest gearing and I just plod along. It's all I can do to keep pumping. I am considering slapping on a 12-25 for my hill days to get me to spin up a bit more. How big a difference would 12-27 be. Will the last 2 gears be too high?

Edited by Modie 2007-11-10 5:14 PM

2007-11-10 5:43 PM
in reply to: #1047252

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Champion
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Evergreen, Colorado
Subject: RE: 11-23 vs 12-25 vs 12-27

I ride a 12-27 on my tri bike because  I live in a hilly area (and I suck).  I have also screwed up and accidentally left my trainer wheel with the 11-23 on the bike when I took it to Colorado to ride.  Oopsie.   Anyway, I didn't notice TOO much difference trying to ride the 11-23.

But from years of riding the 12-27 there isn't much I CAN'T climb with that thing.  I even rode up a 15% 0.8 mile hill.  That hurt, but I made it to the top!

Honestly...if it was just for one race I would try to make the cassette you already have work.  There isn't all that much difference IMHO.   Maybe just do more training on hills to keep your legs from giving out.

Can you pre-ride the course in the spring to see how it goes? 

2007-11-10 6:11 PM
in reply to: #1047252

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Pro
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Los Angeles, CA
Subject: RE: 11-23 vs 12-25 vs 12-27
It's hard to say without riding the course. I personally run compact cranks and a 12-27 in the rear. You might also want to look at getting compacts and keep the 11-23. It would be close to 11-23 and 53/39, and it would be lighter too.

Toward the bottom of this article link, you see a chart which breaks down some cassette and crank information you might find useful.

http://www.slowtwitch.com/mainheadings/techctr/gearing.html
2007-11-10 8:02 PM
in reply to: #1047252

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Champion
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MA
Subject: RE: 11-23 vs 12-25 vs 12-27

I ride with compact cranks on all my bikes and vary cassette by the terrain. On my training wheel I use 12-27.

My sweet spot of RPM is 97-98, so if I ride the hills and my cadence in my easiest gear is 65 or below 80 and my power is super high I'm trashing my legs so going to a different cassette is key.  

It really depends on you and your cycling abilities what cassette to go with. So on hills when you are in your easiest gear what is your cadence?

For me I'd rather have an extra gear or two rather than kill my legs on the hills.

I just bought a new cassette that is a 11-28 (Sram makes it but is Shimano compatible) so it is similar to 12-27, but goes from 25 to 28 instead of 25 to 27 and the 11 vs the 12. I don't really care about the harder gears. I want to try it out as I think it will help me keep my power more level on steeper climbs.  

If you have a 10 speed bike Ultegra cassettes are about $75 list so on Performance bike or similar lots less...why not go for 12-27 and ride the hills and see what you think then if you find it to easy or you never use the 27 get the 12-25.

I do think with proper cassette I think you'll enjoy hills more. 

2007-11-10 9:48 PM
in reply to: #1047252

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Master
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Harvard, Illinois
Subject: RE: 11-23 vs 12-25 vs 12-27
I have a 12-25 setup with compact cranks on my bike. I love it. I like to ride with a high cadence and the compact cranks made it much easier.
2007-11-11 1:06 AM
in reply to: #1047252

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Extreme Veteran
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Brambleton, VA
Subject: RE: 11-23 vs 12-25 vs 12-27
I am in the process of buying a tri bike (a Felt) and have been giving the gearing lots of thought. Considering that you are looking at one race - this might not apply. I opted for a 50/34 up front and 12-25 in the back. I will eventually switch to a 50/36, but that crank set is non-existant is Switzerland at the moment (?).

Check out the following web site: http://www.sheldonbrown.com/gears/

You can run a bunch of simulations to figure out what you gain (or lose) with different gearings. The long of the short . . . you might what to keep the back as it is and change the front to a 50/34 - you will pick up two extra gears.

Best of luck.

ps: I am not a veteran

Edited by swiss tri 2007-11-11 1:07 AM

2007-11-12 3:10 AM
in reply to: #1047252

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Pro
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, New Hampshire
Subject: RE: 11-23 vs 12-25 vs 12-27
I like the 11-23 and the 12-25 cassettes since the gearing doesn't have major steps. The 12-27 is a bit too open for my taste...

On my road bike, I use a 50/36 with an 11-23, and on my TT/Tri bike a 53/39 with 11-23, but where I race it's predominantely flat...

In your case, I would recommend getting a 12-25 for the hillier rides. It only takes minutes to swap out a cassette...
2007-11-12 6:32 AM
in reply to: #1047252

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Champion
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Montague Gold Mines, Nova Scotia
Subject: RE: 11-23 vs 12-25 vs 12-27
You can use a gear ratio calculator like at www.sheldonbrown.com to compare gear ratios (and speeds at various cadences) to help you decide.

I run a 12-25 and 42/53 on my tribike and can spin most of the hills that I ride. I've been using the same cassette on my race wheels but am hoping to get a 12-23 for racing as I don't need the 11 and except on some coures, don't need the 25.

From Sheldon Brown, at 90rpm, here are the speeds for the lowest gear in your three choices:

39-23 11.9mph
39-25 11.0mph
39-27 10.2mph

So, depending how fast you climb, you can look at what cassette would still allow you to spin the hill

Shane
2007-11-12 8:42 AM
in reply to: #1047252

Master
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Subject: RE: 11-23 vs 12-25 vs 12-27
I say you set yourself up on a single speed, 54x11 and just stop worrying (:

Honestly, I've found that changing the rear doesn't make a huge difference. What does make a difference for me, is to not look more than 20' infront of the bike, so that I don't see the top, and wont beat myself up over it.

2007-11-12 7:02 PM
in reply to: #1047252

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Master
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San Francisco
Subject: RE: 11-23 vs 12-25 vs 12-27

What kind of hills are you talking about?  you can use one of the online gear calculators to see the numerical difference in gearing.  I think the difference between a 39 X 25 and a 39 X 27 with 700c wheels is about 8%.  it was enough difference for me to go for a 12-27 on my tri bike since I know I'll have some major climbs and I'd rather spin than mash if possible. 

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