size does seem to matter

michael10x5 said:

[font=Arial]I'm riding a 12-25 rear and like to do a lot of local climbing in the Santa Monica mountains and other local climbs. But at 50 I'm starting to feel it in my knees so I am thinking about options. Buy a 12-27 rear cassette. Get a FSA compact crankset, or get a triple crankset. Any thoughts.[/font]

I'm using an FSA Energy Compact Crank along with a 12-25. It has stopped me thinking about a triple and the associated cost. Seems like I'm going to be able to go to a 11-23 any day now.

michael10x5 said:

[font=Arial]I'm riding a 12-25 rear and like to do a lot of local climbing in the Santa Monica mountains and other local climbs. But at 50 I'm starting to feel it in my knees so I am thinking about options. Buy a 12-27 rear cassette. Get a FSA compact crankset, or get a triple crankset. Any thoughts.[/font]

Get a gear inch chart.

Thanks for the reply. How's your high end with your 50-12 can you still hammer on the flats?

shadco said:

I'm using an FSA Energy Compact Crank along with a 12-25. It has stopped me thinking about a triple and the associated cost. Seems like I'm going to be able to go to a 11-23 any day now.

michael10x5 said:

[font=Arial]I'm riding a 12-25 rear and like to do a lot of local climbing in the Santa Monica mountains and other local climbs. But at 50 I'm starting to feel it in my knees so I am thinking about options. Buy a 12-27 rear cassette. Get a FSA compact crankset, or get a triple crankset. Any thoughts.[/font]

Are we talking road bike or mtn bike here?? Going from a 12x25 to a 12x27 isn't going to make very much difference. Here's a handy tool to help you figure out what you need:
http://www.sheldonbrown.com/gears/
I just went from a 13x25 to a 13x30 and will be trying it for the first time tomorrow (road bike with 53x39 on the front) - I think this will be ideal for the canyon roads in the Santa Monica mountains.

michael10x5 said:

Thanks for the reply. How's your high end with your 50-12 can you still hammer on the flats?

I find myself able to spin out the 50/12.

You may find this chart t be of some use.

http://www.fullspeedahead.com/downloads/Compact%20Gear%20Ratio%20comparison.pdf