The only thing you lose with a 12-23 when running compact crank is a slight bit of your high end speed. Essentially what I mean is that a 50-11 gear ratio is slightly bigger than a standard 53-12 and a 50-12 is a little smaller. I would only see this effecting you on long down hills where you would hammer. At the point where you would spin out I think you should be coasting and in a tuck anyway. You'd be surprised how fast you can go in the tuck without pedaling.

I'd say go with the 12-23 as I'm assuming that's what you currently have....

I just got a 50/36 and went with a 12-25 on it. I have a 53/39 now with a 12-25 and, and the compact with a 12-25 made my easy gear just a bit easier. Like mentioned about, the higher gears are mostly just for hammering down hills, and I'm a tucker at that point so loosing some top gears didn't matter to me. The goal was instead to get my easiest to be a bit easier as I could use a higher cadence on hills ;)

I'll let you know how that goes for me once the new bike arrives (within a weekish)!

Out of curiosity, why are you switching from a triple to a compact? From what I've heard, although a double is easier to keep aligned you'll have to replace enough components that it just isn't worth it.

I wasn't sure what the things were... it was just something a bike tech once mentioned to me. So you are probably fine. I think on the bike I was looking it it also involved a shifter change and such.

Just thought I'd give everyone an update here on the compact crank upgrade. Short answer -- I like them a lot. With a simple cassette swap, my road bike can now be geared more or less like a road double (Using a 12-23 instead of my typical 12-26) or a road triple (by throwing my 12-26 on the back). All with less shifting and a tighter range between gears. I've had the bike out on the road already and am really pleased.

The one "extra" I ended up opting to buy was an FSA compact front derailleur. My shimano triple worked OK but I had to feather it a lot to avoid chain rub. The compact derailleur lets me use 8 out of 9 cogs in each ring with minimal to no feathering. My existing 105 triple/double STI shifter works fine with this setup.

Total damage wasn't too bad:

Crank and BB: Ritchey Pro 50/34 and Ultegra Octalink purchased from eBay, new: $126.
Compact FD: $30 from eBay ,new.
Tools: $43 for a crank puller, BB tool, and large 8mm hex wrench (my multi tool 8mm lacked enough leverage to loosen my old cranks) I bought all these at the LBS because I'm impatient that way--probably could have gotten better pricing off the internet.

Only other necessary things were a crescent wrench to work the BB tool and bike grease, both of which I already had.

$199 all told. Doing it myself took longer than I care to admit, but was worth it in the long run, I hope.

i have a brand new FSA carbon Compact crank set for sale if you are interested. the cranks are 170mm but they measure up to my 172.5 mm shimano cranks. they are the pro version at about 515grams.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160097959366

I would like the feeling of not worrying about my gearing. I'm averaging about 250W and between my double ring front and the 12-25, I'm just not strong enough to keep cadence up on some of the hills I ride out up here. Cadence drops to like 60rpm, and power down to 200, and its just working me at that. I've got a 12-27 ordered. Hopefully that'll do it. I guess the next step is a compact crank. Another $200 or so won't kill me, but when will it end??? Haha.

Try riding Colorado passes! My max speed on the display is stuck at 54.4 mph. My buddy also wants me to mention that he will vouch for the 58mph we hit coming down Wolf Creek pass.

Just to keep it on topic, over the summer when I was in top cycling form, I could pedal up to about 41 mph with a 50-12 setup. I don't know what my cadence was.

So after this weekend I love my compact even more... 88ish miles and over 13,000 ft of climbing, and I didn't ever really worry about not having enough gears! I'm sold!

If it helps, I also switched to a Ritchey Pro 172.5mm a bit back. Been loving life ever since.