compact cranks

[OakLeaf]

So I had to do a little spreadsheet just to see. Told you I'm a data geek.

With my standard Shimano 30/39/50 triple and a 12-25 cassette, I have three gears on the puppy gear that are lower than anything I get on the middle ring, and four gears on the big ring that are higher than the highest gear on the middle ring, for a usable 17 speeds. Exactly what I posted earlier that I've been using...

With a standard Shimano 50/34 compact and the same cassette, one would have five speeds on the small ring that are lower than the lowest gear on the big ring, for a usable 15 speeds.

With a standard Campy 53/39 compact and the same cassette, one would have five speeds on the big ring that are taller than the highest gear on the small ring, for a usable 15 speeds if you go at it from the other direction.

Low gear on a 30x25 with a tire rollout of 2091 mm and an effective diameter of 26.2" is 31.44 GI. Low on a 34x25 would be 35.63, low on a 39x25 is 40.87.

High gear on a 50x12 with the same rollout is 108.99 GI, high gear on a 53x12 is 115.80.

TMI yet? Bottom line is, with 21% grades like our club climbed last night (the ride leader's Garmin said it was 24%) I NEED those low gears to get up the hills and the high ones to get down them; and the more close-ratio gears I have in between, the more comfortable my knees and muscles are on the flats. So I'm even more confident than before that I made the right decision in going with the triple.

[katluvr]

Ok, no physics here, nor do I race. I recently went from triple to a compact cassette. I live in the flat world of Flordia--so hills are not my fortey--or they used to not be. We do have some hilly areas that I train in.
Nor do I race.
I was very afraid to lose my "granny gear" for when I did ride the hills.
I LOVE my compact cassette. I think it allows me more range while in my "small ring". SO I can hill climb and then handle the flats. With a triple I was always having to then get out of my small ring to my middle chain ring and also dropping back down again. AND dropping my chain. So for me it was a good deal! And I climb much better!

[Beane]

That would be the biggest cassette your rear derailleur can handle. You can always change the rear derailleur to a longer cage model and put on a cassette with a 34 cog.

Oh duh. Not sure why I didn't think of that...

With a triple I was always having to then get out of my small ring to my middle chain ring and also dropping back down again. AND dropping my chain.

I agree. I've been dropping the chain much less with the compact double than the triple.

[SadieKate]

Dang, I got it right the first time

So do you feel all powerful? Ready to go rip some pavement?

[Scarlet]

add me to the (small) group that advocates the compact double. i just switched (ultegra 10-speed) this year and i'm real glad i did. it is easier to go up hills without the leg burn if you have a smaller chain ring. and i'm having fun finding i spend more time in the big chain ring than i ever did before because of the lower gearing. i'd hate to think of a situation where i'd need more than the 34-25 gear ratio - what a climb that would be!

i'm also in my 50's and carrying about 10 extra pounds. when i lose that weight - lookout!!

AGree totally (apart from being 46 )I do carry about 10lbs too much maybe more if i get on the scales
just changed from triple to compact Shimano 600 Hollowtech 2 'compact' 34/50 chainset.
and there is just no stopping me ... well almost

Scarlet