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Old 12-29-06, 09:44 AM   #1
George
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Which Cassette

I have a Trek FX 7300 and it has a 11-30 cassette and the chain rings are 48/38/28. I want to change the cassette out to either 11-32 or a 11-34. Which one would give me a noticeable difference. Also I was told that the Shimano cassette was better than the Sram because the Shimano doesn't wear out as fast. Thanks for any replys,George
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Old 12-29-06, 10:01 AM   #2
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Quote:
Originally Posted by George McClusky
I have a Trek FX 7300 and it has a 11-30 cassette and the chain rings are 48/38/28. I want to change the cassette out to either 11-32 or a 11-34. Which one would give me a noticeable difference. Also I was told that the Shimano cassette was better than the Sram because the Shimano doesn't wear out as fast. Thanks for any replys,George
I never heard that there was a difference in durability. But the Shimano cassette is probably lighter.

Regarding which cassette ... the 11-32 and 11-34 cassettes will result in something like a 6% and 12% easier gear. But you will lose some granularity with the 11-34. My preference is to go with the widest range.
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Old 12-29-06, 10:11 AM   #3
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Originally Posted by invisiblehand
My preference is to go with the widest range.
Yep!
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Old 12-29-06, 10:11 AM   #4
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You could consider changing the 28 ring for a 26 of course.
It may be thAt your existing rear derr, Deore that is, will not handle the 34. I seem to recall I needed the XT.
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Old 12-29-06, 11:39 AM   #5
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+1 for going down a few teeth on the granny. The 11-34 will need a long cage der. and a few more links.
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Old 12-29-06, 12:38 PM   #6
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Originally Posted by GiantDave
+1 for going down a few teeth on the granny. The 11-34 will need a long cage der. and a few more links.
I did not know that a Deore derailer could not handle a 34-tooth cog. Thanks for the info.
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Old 12-29-06, 01:23 PM   #7
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Part of your problem comes from having the higher geared chain rings. There are folks running 24 even 20 on the small ring. Typical is about 26. My dream ring, and I think it is available in 9 speed, is the 14/34 because it has a good low end and a lot of gearing choices, however I prefer 8 speed for touring. You should go over the gear calculator at Harris cycle and run off the 46, 36, 26, 11-34 numbers. Then you can, run off your current numbers

Here is the first above:

64.2 88.9 113.6
54.3 75.2 96.1
47.1 65.2 83.3
41.6 57.5 73.5
35.3 48.9 62.5
30.7 42.5 54.3
27.2 37.6 48.1
20.8 28.8 36.8

You basically can't use the upper half of the low collumn, nor the lower half of the high collumn. The drop from 27 to 21 feels like you broke your chain, and is a real momentum killer. On yours below you will see that the 30 ring is a 14-15% difference from the next gear on the downshift, while the 34 is a massive 24.5% difference on the downshift. This is the type of nuts garbage that happens when you go for a 34 on a touring bike. I don't mind it so much on rapid ups and downs on my MTB because sometimes I am just grabing an uphil gear vs a downhill gear when making a fast gear change. On a touring bike uphill, the whole idea it to have reasonable shifts and preserve uphill momentum.

Here is your current:

69.2 93.9 118.6
58.5 79.4 100.3
50.7 68.8 86.9
44.8 60.7 76.7
38.0 51.6 65.2
33.1 44.9 56.7
29.3 39.7 50.2
25.4 34.4 43.5


These assume 700 x35 wheels and 8 speed. So if you are running something different, enter your own values, however the basic spacing is built into the rear cluster:

http://sheldonbrown.com/gears/


Now hop on your bike with a load on it or memories of when you did have a load on. Ask yourself:

Did I have low enough gear?

Did I really use the high gears a lot?

Did I have enough options in the mid gear to find my sweeet spot in different conditions.

Depending on what you have, and where you want to go. You make adjustments to high, or low range, maximum range, or greater density. Greater density is the most efficient assuming you can trim your range.
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Old 12-29-06, 03:51 PM   #8
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Quote:
Originally Posted by Peterpan1
Now hop on your bike with a load on it or memories of when you did have a load on. Ask yourself:

Did I have low enough gear?

Did I really use the high gears a lot?

Did I have enough options in the mid gear to find my sweeet spot in different conditions.

Depending on what you have, and where you want to go. You make adjustments to high, or low range, maximum range, or greater density. Greater density is the most efficient assuming you can trim your range.
Very good points.

I will add another option, Harris Cyclery sells custom cassettes that could help you maintain the granularity of your present set up. Last I checked Sheldon Brown has 13-34 and 14-34 cassettes available.

Although those special cassettes, if I recall correctly, are nine-speed cassettes. Alternatives are available in the for the 8-speed configuration.
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Old 12-29-06, 05:23 PM   #9
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That's good to know. I must check that out, I coul really get into a 14 34 for an 8 speed with good distribution.

It just seems sad to retrofit a whole drive train and end up with a stock system off the LBS floor, though that has to be right for some people.

Another thing I do is write out (or copy) the actual gearing range. Stuff like 11-32 looks good, but how do you feel about this one, admitedly a 7 speed: 13-32 (13,15,17,19,21,24,32), not bad till you hit that 8 cog jump. How about this one? 14-16-18-20-22-24-28 on 26 inch wheels you ca get a real granny, and it will not leave you like the Cayote with your feet in a blur over a big drop when you reach down for that low gear. Your aren't racing down any steep inclines though.
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Old 12-29-06, 05:33 PM   #10
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That's what I have is an 8 speed and I haven't figured the chart on gearing yet. I was looking at Performance and Nashbar and I didn't see much on 8 speed stuff.
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Old 12-29-06, 05:44 PM   #11
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Quote:
Originally Posted by George McClusky
That's what I have is an 8 speed and I haven't figured the chart on gearing yet. I was looking at Performance and Nashbar and I didn't see much on 8 speed stuff.
I thought that Nashbar sold a few 8-speed cassettes. But I have not looked in months. Performance generally sells the "latest and greatest."

EBay may be the way to go for older stuff.

The Harris Cyclery (Sheldon Brown) will also put together custom cassettes. Although, as you might guess, they get to be a bit expensive.

If you want to play with different cassettes and gearing, a good gear calculator is

http://sheldonbrown.com/gears/

He has a lot of informative pages that will guide you through this process.
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Old 12-29-06, 06:32 PM   #12
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I cant believe it's hard to get parts for a 2 year old bike. They must do that to keep you buying bikes.Thanks everybody for the replys.
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Old 12-29-06, 09:17 PM   #13
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I don't think you should have much trouble with 8 speed yet. There is even some 7 speed still available.

Check out Spicer. Nashbar tends to buy stuff that they can get at an attractive price rather than stocking a full range of gear.
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Old 12-30-06, 01:26 AM   #14
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My bike came with 700x40c tires, a SRAM PG830 11-32 8-speed cassette, and 28/38/48 chain rings.

I wanted a lower granny for loaded climbing. The easiest swap for me was to change to 22/34/44 rings. That dropped my lowest gear from 23.5 gi to 18.6 gi. The ease on climbs more than makes up for any loss at the top end. And my knees love the lower gearing.
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