General Discussion Triathlon Talk » Need some opinions on rear cassette. Rss Feed  
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2006-05-25 8:41 PM

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Subject: Need some opinions on rear cassette.

Ok, I've got my Tri Bike out on the road and I've noticed a couple of things.  On one end I don't have the gearing in order to spin up the hills and on the other end I don't have the gearing to maintain pedaling down the hills.  Here is the setup:

Chain Rings:  44/56
Cassette:  12-13-14-15-16-17-19-21
Derailleurs:  Shimano Ultegra 600
Tires:  650's
Bike Overall:  Bike has been fit to my size and rides very well, got a very good deal on it and would like it to last several years.

Any recommendations on how to change the setup to get more low end and high end?

Thanks,

Chris.



2006-05-25 8:58 PM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.

As an expert on not being able to get up the hills and just having order a bike that I will be able to climb hills better on I'd suggest do some math to figure out what gearing you need.

Max is great at helping with this, or there is a link you can do some calculations, then compare if you change your cassette what the difference is. Changing the cassette is the cheapest way to go.

The actual formula is:  FRONT TEETH divided by REAR TEETH times your wheel diameter.

I'm getting a 12-27 as I'm doing some hilly courses and I struggle with some hills. When I get stronger on the bike, lose more weight, or both, I'll get a 12-25.

I wouldn't worry as much as having enough gears pedaling isn't as important as down hills can be a nice time to recover a little. My coach recommend a compact crank as I want to stay away from a triple and this gearing will be similar but a little harder than what I currently have. I'll lose some fine tuning in gearing but getting up the hills spinning is more important. I'll also lose a little going downhills as I know I won't use the most difficult gears on the flats.

2006-05-25 10:02 PM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.

The times where you'll be in 56x12 are few and far between.  If you're spinning out in 56x12, it's time to coast anyway. 

Worry more about having enough 'low end' so that you don't cook your legs grinding up every hill.

I ride a 12-25 rear cassette.  I've never needed an 11, and there's been many times where I was thankful for the 25.  I ride flats to rolling.

Unless you're doing 15% grades all the time, I think 12-25 is probably a good all around, any situation cassette.

-Chris 

2006-05-26 12:14 AM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.
Not sure what is avialble for the 8 speed 600 setup. Try a 11/23 cassette if they make one. You'll have one more gear for the down hill and one more for climbing but the split will be bigger between gears. If that doesn't do it you can combine two different cassettes. I do and like the result on my road bike. 11/25 on a 10 speed 7800. Not sure what a 8 speed casette will do with that set up. Should be something like this 11/12/13/ 15/17/19/21/23. or 11/12/13/15/17/21/23/25

You have more climbing gears than most just by having the 650s instead of 700 wheels so 11/23 will make a difference.

Edited by Nob 2006-05-26 12:15 AM
2006-05-26 5:13 AM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.

This is a matter of preference, but I'd agree that if you are spinning out a 56-12, it's time to let gravity work for you and give your legs a rest.

I have found that it's nice not to blow out your legs on climbs, so that drove my gear selection of 53/39 on the front, with a 12-25 on the rear (10-speed setup).

If you were do do any one thing, I'd change the front chain rings.  Maybe your LBS has some extras laying around that you can try.  You should be aware of what this would do to your ratios and shifting patterns.  Maybe an on-line gear-inch calculator would be helpful: http://www.sheldonbrown.com/gears/

Good luck!

2006-05-26 8:22 AM
in reply to: #434885

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Subject: RE: Need some opinions on rear cassette.
tnt2tri - 2006-05-26 5:13 AM

This is a matter of preference, but I'd agree that if you are spinning out a 56-12, it's time to let gravity work for you and give your legs a rest.

With 650 wheels, spinning a 56-12 at 120 rpm is only 40.5mph, some folks like to go a little faster on the downhills. An 11-tooth cog will take that to over 44mph.

One of SB's choices in his calculator is a "MegaRange" 8-speed: 11-13-15-17-20-23-26-34. This would give you the best at both ends, but would (IMHO) make for some weird, inefficient shifting.



2006-05-26 8:27 AM
in reply to: #435000

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Giver
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Subject: RE: Need some opinions on rear cassette.

Nashbar has an 11-28 8sp cassette, but you may need a long-cage rear deraillure (definitely would need one with Bear's mega-range cassette).

http://www.nashbar.com/profile.cfm?category=87&subcategory=1109&brand=&sku=6215&storetype=&estoreid=&pagename=

2006-05-26 8:38 AM
in reply to: #435000

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Cycling Guru
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Subject: RE: Need some opinions on rear cassette.
And you would definitely need a long cage rear derailleur, which means going with a Deore model since there were no long cage rear's in the 8-speed road grupos. Also, getting an 11 for an 8-speed cassette is tricky. You may also have to end up going with a mountain cassette there as well.

Now the cassette hub for an 8-speed is the same for a 9/10 so you could always upgrade. Just means chain, derrailleurs (ideally) and shifters. Gets a bit more expensive .......

Edited by Daremo 2006-05-26 8:40 AM
2006-05-26 9:07 AM
in reply to: #435032

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Subject: RE: Need some opinions on rear cassette.

Daremo - 2006-05-26 9:38 AM And you would definitely need a long cage rear derailleur, which means going with a Deore model since there were no long cage rear's in the 8-speed road grupos.

Nashbar's (I swear I'm not a Nashbar shill) got an LX 8/9sp. compatible derailleure that would do the trick nicely. Match that up with their 11/28 cassette and your good to go for only 55 bucks.

One note: with a wide range cassette, you'll sacrifice fine differences in gearing, which may make finding the "right" a bit frustrating. But you would have the top and bottom end you're looking for.

2006-05-26 9:35 AM
in reply to: #435069

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Subject: RE: Need some opinions on rear cassette.
run4yrlif - 2006-05-26 10:07 AM
One note: with a wide range cassette, you'll sacrifice fine differences in gearing, which may make finding the "right" a bit frustrating.


Totally ....... I just ordered an 11-21 10-spd yesterday because on my 11-23 I kept looking for the 18 that wasn't there and I want it for my race wheels since my "A" race is flat. Only problem is they only have the Dura Ace model in an 11 - 21 which means just more big bucks I have to spend ..... ugh!!
2006-06-02 6:42 PM
in reply to: #435129

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Subject: RE: Need some opinions on rear cassette.

Thanks for all the input, went and bought myself a 39 tooth chain ring and a 12-28 cassette.  For now I've installed the chain ring, that was the much easier job.  It should help on the hills on Sunday so I don't fry my legs before the run.

Chris.



2006-06-02 7:00 PM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.
I'm a little late as you've done your shopping...
On my old bike (also an 8 speed) I have 52/39 and 12-23. Whenever I went to the mountains I replaced the cassette with a 12-28, and could get around fine. As you have 650 wheels you should have no problem with your new equipment.
I would though suggest putting back you old cassette on flatter terrain as you will probably miss some speed in the middle range, and you probably won't ever need anything above 23.
Good luck
2006-06-02 8:44 PM
in reply to: #434759

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Subject: RE: Need some opinions on rear cassette.
I'm late also, but I wanted to mention that I have the exact same setup (56/39, with 12-23 on the back, 650c wheels) on my tri bike. It's been enough to do races in Clermont without blowing a gasket, so far. The front shifting isn't exactly "click-there" like my road bike since it has the big size differential, but it does shift.
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General Discussion Triathlon Talk » Need some opinions on rear cassette. Rss Feed