Compact Crank a viable alternative?

[larrynipon]

Currently riding a 9-speed 53/39 with a 12-27 cluster. When doing steep climbs, I find I need to push 300+ watts. My threshold is around 210. My 3 mile field test averages around 24mph with an average power of 255. I rarely push the 53/12. I am thinking of going with the FSA compact (34/50) and changing out the 12 gear for an 11. I figure this will allow for better climbing rides while still allowing me to maintain a reasonable average speed on the flats.
Comments?

 

[peterpen]

A 39x27 is smaller than a 34x23, so you'll actually end up with a harder gear to push on climbs. At the same time, the 50x11 is bigger than you 53x12, so if you rarely use the 12 currently, you'll even more rarely use the 11 w/a compact set-up.
Of course, you could keep your current cluster and just change the crank, which will give you extremely small gears for climbing. (But, obviously, if you need to push 300+ watts on climbs now, you still will regardless of gearing.)

 

[gclark8]

Just change the inner (39t) chainring for a 36 or 34 tooth, leave the rest. (I have a 38t inner for sale)

See: http://www.sheldonbrown.com/gears/ and make some comparison speed tables.

 

[peterwright]

I made the same change but have a 23 or a 25 on the back with a 34/50 - feels much better and I can now hold a better and smoother cadence on the climbs.

 

[RapDaddyo]

I made the same change but have a 23 or a 25 on the back with a 34/50 - feels much better and I can now hold a better and smoother cadence on the climbs.

Ditto. With a compact crank on front, you can have several clusters and change them easily and quickly for a specific course. I have a range of cassettes from 13/29 to 11/21, giving me my preferred cadences for almost any course. Of course, the most challenging course to setup for is one with a long, steep climb and a long, steep descent. Tough decision, that one. That's when I'd like to have an 11/29.

 

[acoggan]

Just change the inner (39t) chainring for a 36 or 34 tooth, leave the rest.

Can't be done: the smallest chainring that will fit w/in the bolt circle diameter of a normal crank is a 38 tooth (and even then you have to go aftermarket, e.g., TA, as Shimano and Campy don't make anything less than a 39).

 

[Sprint2Win]

On hilly races I use the 50X34 compact with a 12/27.
It worked out great for me.

Currently riding a 9-speed 53/39 with a 12-27 cluster. When doing steep climbs, I find I need to push 300+ watts. My threshold is around 210. My 3 mile field test averages around 24mph with an average power of 255. I rarely push the 53/12. I am thinking of going with the FSA compact (34/50) and changing out the 12 gear for an 11. I figure this will allow for better climbing rides while still allowing me to maintain a reasonable average speed on the flats.
Comments?

 

[frenchyge]

I can't believe no one's stated the obvious yet:

Just increase your FTP.

 

[larrynipon]

I'm keeping my 12-27, but changing the 12 to an 11.

A 39x27 is smaller than a 34x23, so you'll actually end up with a harder gear to push on climbs. At the same time, the 50x11 is bigger than you 53x12, so if you rarely use the 12 currently, you'll even more rarely use the 11 w/a compact set-up.
Of course, you could keep your current cluster and just change the crank, which will give you extremely small gears for climbing. (But, obviously, if you need to push 300+ watts on climbs now, you still will regardless of gearing.)

 

[gclark8]

Can't be done: the smallest chainring that will fit w/in the bolt circle diameter of a normal crank is a 38 tooth (and even then you have to go aftermarket, e.g., TA, as Shimano and Campy don't make anything less than a 39).

Yes, You are right for a 130 BCD crankset.

I was thinking about 110mm BCD, the "normal" compact crank BCD, and yes, TA rings not original.

We have good access to Sugino and TA here in Aus (Geenspeed) so I am doing these at the moment:
Selling a spare 38t 110mm BCD inner Sugino to a (34t) compact owner,
Changing the 42t middle RPM on the Felt to a 39t TA.
Changing the 30t inner Sugino on the Wheeler to a 36t TA.

 

[WINGNUTT]

Currently riding a 9-speed 53/39 with a 12-27 cluster. When doing steep climbs, I find I need to push 300+ watts. My threshold is around 210. My 3 mile field test averages around 24mph with an average power of 255. I rarely push the 53/12. I am thinking of going with the FSA compact (34/50) and changing out the 12 gear for an 11. I figure this will allow for better climbing rides while still allowing me to maintain a reasonable average speed on the flats.
Comments?

I would highly recommend this change. I live in a very mountainous area, and run a 50/34 with a 12/30 cassette. It makes a huge difference in your ability to maintain steady power output over a long climb, and will make your legs much fresher for the next day too. I blow by guys all day long who are lumbering away with 53/39 cranks and wonder to myself what on earth is wrong with these people.

My only comment is that I have had poor luck with the FSA cranks. They are nice and light, but both of my sets make noise in the bottom bracket (creaking). I've tried tightening, loosening, greasing, de-greasing, teflon tape, etc. and the goddam things continue to chirp away. Finally fixed the problem when I swapped to a Shimano R700 compact - cheaper and a bit heavier, but most importantly.... silent!

I never had a problem with the 12 tooth gear - just spin those legs a little faster.... it's never really bothered me and I've never come close to getting dropped on a downhill.