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FSA Compact Crank - chainring question(6 posts)

FSA Compact Crank - chainring questionridewt
Jan 9, 2004 7:29 AM
From what I hear, the new FSA compact cranks have chainring options of 52, 50, 38, 36 and 34. I run Campy 10 and have a couple 12-25 cassettes. On a new bike, I'm considering going to the compact crank so that I can get an easier gear than 39/25, for the handful of times when I need an easier gear. I'm wondering what kind of restrictions I might encounter if I run the 52 with a 36 or 34? Would I need to use a longer cage derailleur? My preference is to avoid using a different derailleur. Also, does anyone know where I can find a gear chart that gives the different gear sizes for various chainring and cassette sizes? Thanks. By the way, has anyone heard any rumors of Campy or Shimano jumping on the compact bandwagon? They're missing an opportunity.
I just bought one, and here's a gear chart linklendog
Jan 9, 2004 7:54 AM
just bought the compact pro to replace my Ultegra. I have some very steep hills where I live and wanted an easier granny so I can spin up them easier. Cant speak on Campy, but from the research I have done, I should not have to switch out my DA rear derailer, just remove a link or two from the chain. I also only loose 3/4 of my current top end gear (goes from 119 gear/inches to 112) on a 27/12 cassette. I will post with what I think of the crankset once I actually get it and install. I also got it becasue we are planning to go to the TDF this year and do some of the Alp's climbs.

here is a good gear chart link:
http://www.bikecult.com/works/wheelsizes.html

best,
lenny
BTW - I went with the 50/34. <nm>lendog
Jan 9, 2004 7:56 AM
re: FSA Compact Crank - chainring questionglia
Jan 9, 2004 7:53 PM
I have been using a 50/34 for the past 6 months with a 12/23 cog and love it. If anything you may be considering a 50/36 but that takes away part of the benefit of a really low gear. If you take a 53 or 53 with the 34 the difference between the gears becomes even greater than it is so that you have to shift up 3 gears when you go from the large to the small ring. As it is you already have to shift 2 gears to even it out. That's about the only negative thing I have to say about those cranks.
re: FSA Compact Crank - chainring questionPaul Arlinghaus
Jan 12, 2004 1:10 PM
If put a 53t chainring on the compact with a 34 small ring and run a 12-25 cassette, then technically a standard road rear deraileur does not have enough total capacity. Dura Ace rear deraileur is spec for a total capacity of 29.
For a 53/34 with a 12 -25 cassette the capacity is (53-34) + 25 -12) = 32. This means that with a standard road rear deraileur, if you are in the small chain ring and the smallest cogs, your chain will not have much tension. This is very common for mountain bikes, and since you shouldn't be on the small end of the casettein the small ring, this really shouldn't be a problem.

If you really want a small gear for the mountains, run a mountain bike cassette and rear deraileur with a compact crank.

Campy and shimano will be hard pressed to release compact cranks because there are too many people out there who wouldn't understand that they shouldn't riding in the 39-12.
More importantly...Ian
Jan 13, 2004 6:56 AM
...I don't think the rear derailleur capacity really matters here. I believe the D/A front derailleur has a capacity of 15 teeth, although I have pushed it to 16 teeth before. But on 53-34, that is 19 teeth. Would the front derailleur even shift?

Ian