RoadBikeReview.com's Forum Archives - Cyclo-Cross


Archive Home >> Cyclo-Cross(1 2 3 )


Gearing for new CX Bike(5 posts)

Gearing for new CX Bikelexington476
Dec 13, 2003 6:49 AM
I almost have all the money saved for the CX bike I am building; yes now that the season is over, next year . Anyways, I am most likely going to get at 12-27 for the rear, but cannot figure out what I want for the front. I want a double up front so this bike is not for just pure CX racing. In racing my MTB hardtail all CX season it has a 44/32/22 in the front, I only used the 22 a few times on steep hills I should have run (the MTB racer in me, trying to ride it [it only worked about 25% of the time]), I used the 32 most of the time, and the 44 a few times on the pavement. In the 32 ring, I would make pretty much full use of the 11-34 in the back. When going down hill a few times on pavement I would spin out in the 44/11, this only happened one or two times. This bike is going to be outfitted with approximately Shimano 105 parts level overall.

Therefore, I would like to get some suggestions on what I should start with in the front?

I think I will end up getting several rings anyways, as time goes on, as I get use to the bike and/or stronger.
Compact double 110mm BCD best betpitt83
Dec 13, 2003 12:47 PM
If you go with a standard double, practical limitations dictate lowest to be a 48/38 combo. The 38 with a 12-27 is OK, but you'll likely be jonesin' for something lower. If you go with a 110, you'll have infinitely more small ring choices for chain rings to gear where you want.

OR: Go with 11-34 rear and MTB read deraileur and chose a standard 130 BCD double.

I have the 48/38 130mm BCD with 12-27 and it's OK, but sometimes, I click and nothing. I'm already down there. Makes you stronger though.
Compact double 110mm BCD best betlexington476
Dec 13, 2003 6:02 PM
Oh, so Shimano I will not be able to get lower then a 38? I think I will need something lower then that. Just so I know for sure, what is 110 vs. the 130? What size is that?
Compact double 110mm BCD best betdamon
Dec 14, 2003 1:46 AM
110 vs. 130 BCD (bolt center diameter) refers to the size of the bolt pattern. You know how in the mountain bike world there are "compact" and "standard" cranks that require different chainrings, due to the bolt holes not lining up? This is exactly the same thing. 130bcd is a standard shimano road bolt pattern, while 110 is a fairly common mtb bolt pattern.

You should be able to see how a larger bolt pattern limits how small of a chainring you can install. A "standard" mtb crankset with a 110bcd is really a good idea for a 'cross bike intended for a lot of dirt use.

http://www.sheldonbrown.com/gloss_bo-z.html

Good luck,
-Damon
A crankset with 110 BCD will give the most flexibility...The Walrus
Dec 13, 2003 1:04 PM
...in your choice of rings. I like a 48/34 or 48/36 combo, and I'm using RaceFace, Cook Bros. and old Shimano cranksets. A number of companies (TA, FSA, Sugino, Ritchey, etc.) are making cross-specific cranksets supplied with rings; you can check out some of these at www.schwabcycles.com. Sounds like these would be a good match for the gearing you're used to on your hardtail.