Cyclocross - low gearing
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04-25-10, 07:40 PM
I'm working with a bike shop on a cyclocross bike. I like it, except the compact double gearing. I'm wondering if you all have any suggestions.
I'm not racing this thing, but I am climbing some single and double track (by riding, not running up on foot!) and a lot of hills. With my old bike, by the end of the day, I want to use the granny gear to climb, using 24x24 or 24x21 (with 26 inch wheels).
This new compact cross bike has a lowest gear of 34x27 with 27 inch wheels.
What are my options?
- go to a triple - apparently this might be expensive, most of the drivetrain would need to be swapped
- get a 13-29 cassette - cheaper, but still not quite as low as I'd like
04-25-10, 08:07 PM
A cassette with a 30T low will get you about the same as the 24x21 gearing you were used to, you'll need a 36t to get as low as the 24x24. You'll likely be able to run a road rear der with a 30t, but a 36t will take a long cage mtb der.
04-25-10, 08:45 PM
I should have also mentioned that this is a 10 speed (Shimano 105).
30t sounds nice. But is there a 30t 10 speed cassette? 10 speed jumps from 29t to 32t (edit: on Sheldon Brown's web site).
04-25-10, 09:00 PM
Yes, and on the Harris Cyclery (Sheldon Brown's employer) page you'll find the "century special" which is a 14-30.
Personally, looks like you're needing a mountain bike rather than a cross bike. But, you could run mountain bike gearing on it with the STI's. I converted one of mine to it for some strange reason. Then quickly converted it back. I used a Deore crank, front and rear derailleurs and a 12-34 cassette. There wasn't much I couldn't climb with it, but it wasn't that great for the road. I think I picked everything off ebay for about $150-200.
Edit: opps, that cassette is a 9 speed. I wonder if you could simply add another cog and spacer to it? Bet you could.
04-25-10, 09:20 PM
IRD makes, even though Harris doesn't list it, 10s cassettes with final of 28, 30, 32, 34 teeth.
I only know one 36t and it's a 9s.
04-25-10, 09:23 PM
Another option may be to switch to a "Super-Compact" Double, using a triple crank but with only two rings, double shifter and double derailleur, you could get down to a much smaller inner ring.
04-25-10, 09:42 PM
Yeah, this is unusual. I do use a mountain bike now. I wanted a light mountain bike (cross country, maybe) with drop bars, but cross bikes seem to be the closest beast unless I go to something much heavier - like a Fargo.
I guess I should have also mentioned that this is going to be my commuter bike. To stay off the numbered routes during rush hour, I take snowmobile trails and washboard dirt roads. That's 1/3 to 1/2 of the route (the fun part!). The rest of the route is pavement.
Anyway, if I could make that CS922 Century Special 13-30 a 12-30 by adding a cog, that would be just about perfect!
04-29-10, 08:37 PM
Well, the triple wasn't an option. And the store didn't want to put anything lower than a 27t on the bike, they said they didn't want to support it if it shifted poorly. I bought the darn bike anyway. Call me a fool.
Also, no go on adding a cog to 9 speed. Maybe with friction shifters, but not with STI. Spacing is different.
So. I read that Shimano will release a 10 speed 11-34 mountain cassette (http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/news_and_info/news/dyna-sys__shimano.html).
Is the MTB Shimano cassette compatible with road? I'm trying to decide if I should buy a 11-28 Ultegra and tune it myself or wait for the wider range MTB cassette.
04-30-10, 08:33 AM
Shimano is going 10sp. Sram already has a 10sp MTB group. Also, the Sram Apex group has a 11-32 cassette. I would do a MTB der and a bigger cassette and leave the crank be.
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