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Old 10-07-09, 12:36 AM   #1
brendon_ak
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Chainring Size w/ Compact Crank, and Wheel Questions

Hey,

I have recently become the owner of a Ridley Crossbow (yay me), and I am absolutely in love with the machine. I have a few go fast bits that I'd like to install, but I'd like some opinions first.

I have an extra Red compact crank. It's got the 50/34 combo. I was assuming that the Crossbow would have a compact crank and I could simply switch the rings, such is not the case. What is a good ring combo? Can I keep the 34 and swap out the 50, or do I need to ditch both and run the typical 38/46? The cassette is a 12/25.

For wheels it comes with some seemingly bombproof fulcrum racing rims. I have some leftover Real Designs Ultrasphere rims from my Litespeed. They are 20/24 spoke, same as the Fulcrums, and weigh much less too. I have read about some people having problems on the road with the Ultraspheres, and others not. I've got a couple thousand miles on them and they're fine, but I don't want to destroy the wheels during cross (I could sell them for some coin and build up a set of tubulars, rather than make more scrap).

Any thoughts?
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Old 10-07-09, 09:11 AM   #2
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Do you have a sense of what your race courses are like? Do you even need to run a double? What does the Crossbow come with? Do you tend to mash a big gear?
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Old 10-07-09, 10:38 AM   #3
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36/46 and 12/25 is a pretty common setup for cross, depends on the course, obviously.
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Old 10-07-09, 12:48 PM   #4
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Quote:
Originally Posted by MONGO! View Post
36/46 and 12/25 is a pretty common setup for cross, depends on the course, obviously.
Yeah.

If we want to talk about common setups, here's what I've been seeing the last 3-4 years (I can only speak to Shimano setups):

46/34
46/36
46/38
48/38
39 single
40 single
42 single
44 single

A combo that has me intrigued me now that CW World is making smaller outer rings is 42/34 and 44/34.
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Old 10-09-09, 12:09 AM   #5
brendon_ak
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Thanks for the responses.

No idea what the courses are like, I'm in Salem, OR and will be racing in the NW (and nationals in Bend)

Crossbow came with a SRAM S300 crank, no markings of chainring size, I'd say 38/46 though.

I threw on my extra Red compact crank and was able to get a 46t outer ring from my LBS. I was hoping for a 42 or 44 since I'm working with a 34 inner ring, but we were unable to find any outer rings with 110bcd that were 42 or 44.

I've only ridden cross once, and it was on a practice course. I've got my first race this Sunday, and I can already see the appeal of a single chainring up front. That said, we'll see how the race goes...
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Old 10-09-09, 06:54 AM   #6
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cyclocrosswold.com has 42 and 44 T outer rings:

http://cyclocrossworld.stores.yahoo.net/thkoouch.html
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Old 10-09-09, 07:55 AM   #7
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go find a gear inch calculator and look at speeds around 60rpm in your smallest gear and around 90rpm in the biggest gear. If they cover the speeds you'll hit in a race then you're all set.
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