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Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

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Old 05-31-07, 10:50 PM   #1
KeatonR
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Help me understand compact gearing

I apologize in advance for my ignorance on this topic.

Over the winter I bought a carbon crankset for my Poprad. Looked cool, was carbon, weighed less than my existing crankset, and had similar (so I thought) chainrings -- the original Poprad (Bontrager) rings were 46/38, the FSA rings are 46/36. The FSA crankset I bought and installed is a compact crankset. I had no idea what that meant when I bought it. After one ride on the flats, I realized I was missing gearing on the high end.

My question is, how off am I now, and what might I do to get back to where I was? I have two wheelsets, a cross set with 12-25, and a road set with 12-26. I thought the gearing was perfect then. I climbed well with those setups, rarely dropping to the 38 when climbing, and I live in CO (which makes me wonder if I'll ever use a compact 36) so I'm worried that I screwed up by unknowingly going to a compact crankset.

So do I need new rear cog clusters? Or get bigger rings for the compact crankset?

Thanks,

Last edited by KeatonR; 05-31-07 at 11:04 PM.
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Old 06-01-07, 01:26 AM   #2
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this explained it all to me, at least: http://bikeforums.net/showthread.php?t=241679

HTH
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Old 06-01-07, 03:57 AM   #3
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Quote:
Originally Posted by KeatonR
I apologize in advance for my ignorance on this topic.

Over the winter I bought a carbon crankset for my Poprad. Looked cool, was carbon, weighed less than my existing crankset, and had similar (so I thought) chainrings -- the original Poprad (Bontrager) rings were 46/38, the FSA rings are 46/36. The FSA crankset I bought and installed is a compact crankset. I had no idea what that meant when I bought it. After one ride on the flats, I realized I was missing gearing on the high end.

My question is, how off am I now, and what might I do to get back to where I was? I have two wheelsets, a cross set with 12-25, and a road set with 12-26. I thought the gearing was perfect then. I climbed well with those setups, rarely dropping to the 38 when climbing, and I live in CO (which makes me wonder if I'll ever use a compact 36) so I'm worried that I screwed up by unknowingly going to a compact crankset.

So do I need new rear cog clusters? Or get bigger rings for the compact crankset?

Thanks,
A lot of riders that switch to compact swap cassettes to an 11 tooth version. See if you can beg/borrow one and try it out. It will return some of the top end you are missing. Good luck

Tim
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Old 06-01-07, 06:40 AM   #4
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I don't understand how you are loosing speed in the flats when you're highest gear (46-12) is the same as with your old cranks. The only difference is going to be if you are in your smaller chain ring (a 36, as opposed to a 38).

Technically, both of your cranks would be considered "Cyclocross Compacts" because the rings are different than a traditional Road compact (a 50/34).
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Old 06-01-07, 06:44 AM   #5
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I dunno, felt like I had a lot more pedaling that I could have done when I went out.

From what I've now been reading from the link above, it appears I've been overthinking this a bit. One thing I will do is order a new 38 inner ring from FSA and ditch the 36, and then I'll think about going to a cogset with an 11 for the road wheelset, and leave the cross wheelset the same.
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Old 06-01-07, 07:00 AM   #6
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Have done some more digging and this is looking really useful:

http://sheldonbrown.com/gears/

Especially for someone who is (obviously) not a math guy.
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Old 06-01-07, 12:23 PM   #7
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yeah, 46 = 46. Doesn't matter if it's a compact or standard crankset. Did you perhaps change the crank arm length as well?
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Old 06-02-07, 03:48 AM   #8
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Quote:
Originally Posted by KeatonR
I dunno, felt like I had a lot more pedaling that I could have done when I went out.

From what I've now been reading from the link above, it appears I've been overthinking this a bit. One thing I will do is order a new 38 inner ring from FSA and ditch the 36, and then I'll think about going to a cogset with an 11 for the road wheelset, and leave the cross wheelset the same.
If your problem is top end gearing, don't waste any money on a new inner chainring. It has ZERO effect. Get the new cassette. Good luck

Tim
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Old 06-02-07, 08:26 AM   #9
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Definitely now understanding that a 46 = 46. Was in a bit of a late-night panic when I first posted, thinking I had screwed up by going to a compact crankset without even knowing what it was.

I think I will try an 11 on my road wheelset and from there think about a 38 inner ring. I never use the third ring on my mountain bike, and I liked the 38 on my previous setup for climbing.
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