Cyclocross - ?good crankset for two small chainrings
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I did my first CX race today. What a blast! I did it on a loaner. Now I am looking to buy. I was considering some options in the $1,000-1,300 range. What I don't like about those is that they more often than not run 39/53. My friend's bike is 26/44 (12-26) which suited me fine. Redline Conquest Pro runs a 36/46. This is better but it seems 36 is the smallest chainring that particular crank will take. Bianchi Axis comes with small cross-oriented chainrings and seems to have a crank that will take even smaller ones.
I am not interested in the offerings with a triple chainring since they all have a 52 or a 53 as the biggest, which is of no use for me on a X course.
My question is, what is a good crank that will take two small chainrings? I don't want to run a MTB triple crank with only two chainrings because they will not be well aligned (it is desinged such that the middle chainring lines up with the middle cog). I am looking for a product that I can ask a LBS to substitue for the 39/53 monster that most come with (plus I want 175 mm arms).
11-04-02, 10:35 AM
I havent seen a cross race yet where i've needed anything less than a 39 chainring. Typical cross rings are 38 or 39 with a 46 or 48. If you run a single chainring you'll use a 42 or 44. The rear casette should go up to 27 but can be as big as 32. I would recommend racing with a road crankset and vary your rear casette.
11-04-02, 11:00 AM
Specialities-TA make a top quality double with a 110mm PCD, ideal for CX or lightweight road bikes for the slower rider,
Stronglight make a much cheaper one (model 80) which you can run as a double or triple from 28 to 52, using just one set of bolts.
Thanks to CrossProvidence and MichaelW for their excellent replies. I went out and bought an '02 Redline Conquest Pro last night, which has a 130 mm BCD crank by FSA with 38/48 chainrings and a 12/27 cassette. I'll race it a few times before I decide on any mods.
11-06-02, 10:52 AM
Sounds nice! Good luck with the racing. I loved the nationals course in Baltimore last year. I'm trying out the single 42 chainring this year. I just got a Weyless carbon crankset with double chain guards. I think i'm spending too much but oh well. One thing I did learn this year is that you cant run a single chainring withouth the chainring guards. The chain falls off and you dont have a front deraileur to shift it back on. That was a bad race. Have a really good time on the new cross rig.
Congrats on the new crankset. What arm length did you go for? I had talked about wanting 175 mm (instead of the standard 172.5) because that's what I have on my road and mt bikes and I think it gives me good climbing power. But I guess the shorter ones are better on the knees for a shorter rider (I ride a 52 cm frame) and I have some shoe/front wheel overlap that I don't want to make worse.
Also, out of curiosity, when does the chain fall off the single chainring? Over bumps, or when you shift? I remember the five speed bikes we used to have when I grew up with only a rear derailleur. I don't recall the chain ever falling off. (Of course, I never crossed them).
11-06-02, 02:54 PM
I stuck with the 172.5 crankset. I ride a 54 road bike (52 cannondale cross and 54 empella cross). The longer crankset was a trend around late eighties to early nineties with big miguel indurain using long cranks and winning the tour. There has been a few studies where they test power vs cranklength and no one has proven that longer cranks produce more power. I know that physically the torque is increased with the length of the lever arm but the biomechanics of it seem to be a bit more complicated. Thats why you have some track riders on 165 crankarms. I have the 175 on my mountain bike where the lower cadence is more common but when cadence and endurance are involved, i'm sticking with the same size crank as my road bike. Also, my toe can touch the front wheel with 172.5 cranks when i'm clipped in but i've never hit my foot with my tire while riding.
As for chain drops, it happened at two places on the race course. One was a downhill with a bumpy corners where I was leaning over. The other was a really bumpy flat following a remount. I'm not sure if additional chain tension from a shorter chain would have kept it on. It also may have something to do with the chain line. I had the single ring mounted on the inside chainring location and was in a small rear cog (downhill) when it usually fell off to the outside of the chainring.
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