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Discussion Starter · #1 ·
Well, I love my Fulcrum compact cranks. Except when I want to descend fast and I'm spun out. SO, here's the question...can I put a 52 tooth chainring on my compacts for mountainous races? Anyone?
 

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Don't see why not - the FSA K-Force Light compact crankset on my crit bike came standard with 52/38 chainring combination but could also be purchased with a 50/34.
 

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sjbryson said:
Well, I love my Fulcrum compact cranks. Except when I want to descend fast and I'm spun out. SO, here's the question...can I put a 52 tooth chainring on my compacts for mountainous races? Anyone?

Making a 52-34?

I don't know about you, but little old me-but in most situations where I spin a 50/12 out-odds are I'm also going to spin out a 52-12 just about as quickly, yes? Not worth the bother, presuming it would work, IMHO.
 

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haole from the mainland
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Sure, if you have a 36 for your smaller ring. I think a 14-tooth jump is the most a front derailleur can handle.

You could also swap out your cassette for one with an 11-tooth cog, as I'm guessing you have a 12-tooth cog. A 50-11 will give you a bigger gear than 52-12.
 

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Discussion Starter · #5 ·
"I don't know about you, but little old me-but in most situations where I spin a 50/12 out-odds are I'm also going to spin out a 52-12 just about as quickly, yes? Not worth the bother, presuming it would work, IMHO."

Well, that's what I thought too--untill I got passed by several people, spun out, on a steep, into the wind descent.
 

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Discussion Starter · #7 ·
tantra said:
It would be much more effective to keep the 50 ring and get cassette with an 11t cog. 50 to 52 is a much smaller jump than 12 to 11. Excel sells these for Shimano cassettes.
Well, I do have an 11 on there. Maybe it's just me...or maybe I should learn to spin 135 rpm...
 

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SRAM makes a 11-28 for a wide range of gear combinations. I almost got one, but decided to stick with Shimano and a 12-27 for my compact cranked Madone when I changed the cassette to make a climbing "super century" a little easier. My LBS told me Shimano is coming out with a 11-28 later this year (at least according to the rumor mill). That'll be sweet for the flats and climbing :p

Bruce in Redding
 

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I think a 14-tooth jump is the most a front derailleur can handle.
Shimano compact cranks are 50-34; a 16 tooth difference, and they shift very well with a standard front derailleur.

I suspect a jump from 52-34, though, is going to be way too much and lead to less than idea shifting in the front. Plus I've never seen that combination, so you won't have the potential advantage of some creative ramping and pinning on the outer chainring to make the upshift smoother.

Also, if you're running an 11-27, 52-34 set up, chain wrap length may be an issue if you're running a short cage rear derailleur. You don't mention what type of rear derailleur you're using, but the recommended chain wrap length for short cage Shimano derailleurs is a conservative 29. 31 works fine. 34 may not.
 

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In my bin o fun in Phx, I have rings for 110mm BCD pattern all the way up to about 54t. Prolly for either the commuter/fixie I was gonna build or backup track rings. I don't remember.

M
 

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TA Nerius chainring

If you want a 52T ring to fit a Fulcrum compact crank, you need a TA Nerius, as Fulcrum uses the proprietary Campy 110 + 112mm BCD. TA makes inner rings of 34-42T, and outer rings of 48-53T in this standard. Most front derailleurs seem to have a capacity of 16T, so you would likely need to use a 52T big ring with a 36T small ring. Alternatively, you could try using a triple front derailleur.
 

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Eyorerox said:
A 52/11 @ cadence of 100 is 38 mph 50/11 is 36.5 mph
A 52/11 @ cadence of 120 is 45.6 mph 50/11 43.8 mph
Sheldon Brown
50/11 is fine for me, just coast when I spin out
Yep. At those speeds, a good tight tuck can net more watts than opening up to pedal.
 

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wow I didn't know Shimano had the 11-27. I like that cassette. May be my upgrade when I replace my 12-27. I even like the SRAM 11-28. Since I don't ride compact it would be nice to have a 28T
 
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