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12-25 or 12-27 cassette?(10 posts)

12-25 or 12-27 cassette?Captain Napalm
Jun 19, 2002 4:24 PM
I just bought a used road bike with a 9sp Dura-Ace 11-23 cassette installed and want to use this primarily on the coast outside of San Francisco (hills!). I'm figuring that I need to swap in a new cassette but am undecided between the 12-25 and 12-27. Which would you go with and why?
re: 12-25 or 12-27 cassette?Ian
Jun 19, 2002 4:41 PM
I ride the 12-27. The 12-25 has a 23 and 25 tooth cog, while the 12-27 is a 24 and 27 tooth, everything else is the same. Down in that range I find the extra two teeth much more important than the smaller gear range. And in San Fran, your hills hit grades in the high teens? I would certainly get the 27.
why not go triple? nmMJ
Jun 20, 2002 1:59 AM
have bothPaul
Jun 20, 2002 4:43 AM
I just use the 27 for our Century which has some big hills. When you're tired, you'll love the 27. Overall, I prefer the 25, find that I spin too much when using the 27 cog for general hill riding. Suggest you get both, and swap off when needed.
Absolutely. Buy both...Sintesi
Jun 20, 2002 5:12 AM
Get a chain whip and the cassette removal thingy and switch 'em out when you feel like it. Once you know how it's the simplest thing in the world to do. Takes 3-4 minutes if you're slow.
Absolutely. Buy both...niteschaos
Jun 20, 2002 8:41 AM
the 25 will give you about 8% more torque than the 23T rear sprocket. You could get a custom casset made though. I'm planning on getting a custom cassette for all the mountains I ride. 2 miles at a 14% grade sucks. I'm thinking of a 13,14,15,16,17,19,21,23,25 setup myself. I never use the 12T because on decents fast enough to use it I'd be coasting and resting for the next climb.
13-25, it includes a 16 (nm)Chen2
Jun 20, 2002 7:18 AM
re: 12-25 or 12-27 cassette?No_sprint
Jun 20, 2002 10:36 AM
This topic was visited a couple of weeks ago. For purely rec riders, things may differ, however, for racers like many of us here, in my experience, 27s just don't exist. Almost everyone on my team is running 11-23, especially if we're road racing. Most road races do indeed have descents where the 11 is necessary to not spin out and to keep up with the pack. There aint a hill in a race or really anywhere that I've ridden that was impossible (though they could be really really tough) to conquer in a 23 as well. Some of our training rides here at least make it almost necessary to train with a 25. Thus, most of us consider the 25 our trainer. Latigo, Piuma, Angeles Crest and Bouquet Canyon come to mind immediately.
Don't make my mistake!!empacher6seat
Jun 20, 2002 12:35 PM
I bought a used bike with a double chain ring (53 x 42) and a 7spd casset (11-21) without knowning anything about bike gears. Well, I now know that I picked a pretty hard combination for a beginner. The steepest hill in my area is around 28%, and I can barely turn the pedals going up that sucker.
12-27 is a safe betcyclopathic
Jun 20, 2002 9:00 PM
as was said above the diff is 2 top bail out cogs.

I use 12-27 on 42 and never find jump from 21 to 24 is to be a problem. Yes it's marginally bigger then 15 to 17, but in situations you use it it hardly matters. I had never found a hill which had a grade tuned to 23 or to 25. Most of the longer climbs are shallower /17-21t range/ or if the grade is right it is too short to matter. 27 can make the diff btw walking and riding, esp on century+ rides