Crank size
 

Hi all-

I had a 2010 Specialized Roubaix 58 comp triple up until recently. I loved it. I am 5'10 with a 34 inch inseam. I am a serious recreational cyclist-not a racer, but like to group ride. After trying a 58 2014 Roubaix comp, the frame felt a little too big. I really felt stretched no matter what adjustments were tried .I rode a 56 and felt more comfortable. I purchased this bike. I am not stretched, but still tweaking saddle position. Have a 120 adjustable stem which I am also playing with. Overall the bike feels pretty good. But I definitely don't have the same power in the big gear that i had with my old bike. The crank on the 56 is 172.5 . Heres the question: would getting a bigger crank-175?- give me the same power i had with the 2010?

At your inseam, either 172.5mm cranks or 175mm cranks are spot on for you. I honestly don't think that you would feel much difference from the cranks alone. The 172.5mm cranks would be a tiny bit easier to spin at high cadence.

I had a quick look for specifications on the bike. Triple cranks often have a smaller large chainring than a double chainring by a few teeth.
One specification that I read specified a 50 tooth large chainring. If the new bike has a 53 tooth large chainring then you would have increased the gear ratio's in the big ring by a noticeable amount. Also I find that getting the saddle in just the right place effects how much power I feel I have.

Anthony

Thanks for the feedback and info. After speaking with my local bike shop mechanic, he suggested that i get a 52 ring. It should come in next week. Still have a feeling that a 175 crank would make a difference.

Thanks again!

I'd move your saddle around a little. I don't know how you've set it up now although if all things were equal, then compared to the 175mm cranks I would have the seat 2.5mm higher with 172.5mm cranks and probably a couple of mm further back.

Also, you might be right. You may fell better with 175mm cranks yet given the cost involved in this change I would try some cheaper adjustments first.

Anthony

a change from 172.5 to 175 is a 1.5% force reduction.
Cheers,
David B.

spend the big bucks on a power meter crank an it will give you numbers to play with. to what benefit? beats me.. IDK.

Too simplistic.