Swapping standard and compact cranks

I recommend riding 7 sisters, your napkin calculations are off by about 15%. Nyes Place hits 23% in short sections and has a constant grade above 15%.
Park, Pacific Island, Bluebird Canyon are all tough climbs.
7 Sisters is a great ride and it is steep.
Check out the profile.

 

Thanks for the replies, I guess my real question is whether or not this swap is something that can be done on a regular basis depending on the particular ride coming up (like swapping cassettes), or whether the chain (Campy 11) isn't really suitable for constantly joining and breaking to handle the different gear ratios - I'm running a 12-27 cassette right now, but I guess I could run an 11-23 with my regular crank and the 12-27 with a compact and not have to break the chain?

In an ideal world, my fat ass would be able to run the gears as is, but until that point, I'm ok spending money

 

The chain won't need breaking. The derailleur takes care of chain length.

 

http://www.panix.com/~jbarrm/cycal/cycal.30f.html

There are several good (but old) articles in Velonews espousing the virtues of running compact cranks. Personally, I was able to run a compact with a 12-27 on a bike that I usually have set up with a 53-39 and a 11-23 without changing a single thing, for the Everest Challenge a few years ago. Knowing what I know now, I'd have preferred to use an XTR derailer with an 9-speed cassette with a 34 - but then, that's just my old knees talking.

By changing, I mean, no change in chain length, no moving front derailer, same bottom bracket, minimal adjustments to the derailer.

 

I like a bail out gear!

I personally think traditional road bike gearing (42/21 20 years ago, 39/23 most new bikes) is OLD SCHOOL. I think mounting bike gearing has had an influence on road gearing. How many riders use their 22/34; not many but it's there. Even if you rarely use the 34/27 its nice to have if your blowing up and the climb is really steep.

I rode a 39/25 all the years I lived in Colorado with no problem but I'm getting older and there are some pretty steep roads in CA (Park Ave. is one that comes to mind) and now I'm riding a 39/27. I rode the Ride Around the Bear several months ago I spent way too much time on the 27 and had a couple of moments wishing for a 34 front chain ring.

Also it depends on the rider; I always like to spin. My riding buddy in Colorado rode a 39/21 and never had a problem but he was always riding a gear bigger than anyone else.

 

Yes, but there's no extra movement left in the derailleur.

At 39/12 right now, the chain is pretty slack and if I drop it to 34/12 by switching to a compact crank, the chances of the thing wrapping go up dramatically.

I know that with a 3x9 chain on the mtb, the only real solution is just "don't go small/small", are road bikes the same way or should I be ok to use every gear combo on there?