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Discussion Starter · #1 ·
I am getting ready to build up an ebay impulse buy frameset. I am trying to get some lower gearing for occasional climbing. I do not want to go triple as I already have a bike with Campy triple that I use for the hilliest stuff. I am debating between Centaur Compact Crank 34/50 with 12-25 or a standard Campy 39/53 with the 13-29 rear setup. Both offer roughly the same overall range (13-29 slightly lower). Any advantages/disadvanatges to either setup? Also, am I correct that the 13-29 requires the medium length derailuer? If I happen to use a 12-25 or 12-23 cassette sometimes with this can I still use the medium cage setup? I assume the compact setup uses the standard short cage der? Is the correct? Thanks all in advance for any thoughtsd
 

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Lizzie will ride free
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DaveG said:
I am getting ready to build up an ebay impulse buy frameset. I am trying to get some lower gearing for occasional climbing. I do not want to go triple as I already have a bike with Campy triple that I use for the hilliest stuff. I am debating between Centaur Compact Crank 34/50 with 12-25 or a standard Campy 39/53 with the 13-29 rear setup. Both offer roughly the same overall range (13-29 slightly lower). Any advantages/disadvanatges to either setup? Also, am I correct that the 13-29 requires the medium length derailuer? If I happen to use a 12-25 or 12-23 cassette sometimes with this can I still use the medium cage setup? I assume the compact setup uses the standard short cage der? Is the correct? Thanks all in advance for any thoughtsd
If the 13-29 gives you the range you want, I'd go that way. It's really just a matter of taste however, as many folks like the compact stuff. Search "compact crank" and you will quickly understand all the issues -- good and bad on both sides. Also, while a 13-29 is specified with the medium cage, you can get away with the short if you want and you set the chain length correctly and avoid crossover gears. Another search on 13-29 will turn up that discussion. A medium cage will shift just as well, and it will of course handle the smaller cassettes that you might use too. FWIW, I went with the 13-29 short cage on one bike, and it works well.

One reason to go conventional is that there are so many inexpensive Chorus and Record doubles on e-bay because of the move to carbon and compact. Also the Chorus brackets have a great reputation.
 

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Dave,

I would go with compact and use the 12-25. I currently ride compact (50/36) with a 11-21 , but I also live in flat ole Houston,TX. Depending where you live or where you ride, if you do lots of long climbing it is nice to have a good gear to spin during hours of climbing. If you get the compact crankset, you can buy bigger compact rings (110 mm spacing) with 52 tooth big ring and a 38 tooth inner ring.
 

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trade-offs...

First, get the medium cage RD. It will work with any cassette you choose and even work with a triple. There is absolutely no shifting penalty.

As for the gearing, the low gears are as nearly identical as you can get. The 50/12 is 2% higher, which is also a pretty trivial difference.

The compact setup provides closer cog spacing between the two lowest shifts. Some folks think the 23-26 and 26-29 shifts with the conventional setup are too large, but it all depends on the terrain you're riding. Sometimes a 2T jump isn't enough and 4T is too much, but 3T might be just right. Other times a 2T jump may be perfect. You can;t have your cake and eat it too.

The last difference is the extra cog shifting created by the wide spaced 50/34. Every time you switch from one chainring to the other, it will require shifting one more cog than the standard 53/39. A 50/36 would avoid this extra cog shifting, and provides a 1-cog lower ratio, the same as a 39/27.
 

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Discussion Starter · #5 ·
thanks all

Many good points made here. I am perhaps leaning slightly towards the standard crank option simply for the cost reason that was cited. I've also noticed the availability of CT cranks on the lower cost internet/mailorder places to be sketchy. I think I could be happing with either. I do like the idea of shifting down the gear range with the CT crank. With a standard 53/39 and 12-15 cassette I find I do a riding a lot right at the crossover point between the chainrings (for me 18-20mph @95rpm). The Compact would probbaly keep me in the big ring more often
 
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