Do It!

The great thing about compact cranks is obviously the ease of climibing and the second benefit is that it allows you to stay in the big ring on more rolling terrain. You won't need to go to the small ring as much on the small-medium sized hills.

Like you said, there isn't much necessity for a 53/12 unless your are giant and can push huge gears. Even in a race, anything over 30mph on steep downhills is just wasted energy when you can tuck and not pedal.

A guy I know, who routinely rides 2:15 give or take a few minutes, for HIM bike split rides a 48 front big ring.

I say go for it.

I plan to put them on my next bike :)

I have a triple on my training bike with 52/42/30 rings in front and a double on my tri bike with 52/39. Both bikes have 12-23 9-speed cassettes. I bring the triple-ring bike for hilly races like Catalina Island where the climbs are truly steep.

While I may not race at 52-12 very often, I do train on that gear a lot so I am reticent to swap to a compact crankset and lose the strength-training.

I'm happy with mine. Went from a triple (52-42-30) with a 12-25 to a compact 50-34 with a 11-23 and its been great!

If you want to cover all of your bases, go with a SRAM 10 spd 11-26 cassette. You'll get the top end for the downhills and the low end for uphills.

Question...if I switched my tri bike to compact cranks (I live in a hilly area and am doing IMWI next year which I hear is a rolling hilly course, do you keep the crankarm lenght the same as what you are riding now??