Road cranks usually have slightly shorter crankarms than MTB cranks to facilitiate spinning and because there isn't as great a need for leverage as there is on a MTB. Are you a spinner or a masher on the road? Do you have knee problems? If you like to spin and/or have knee problems stick with 172.5. If you like to mash and knee's aren't an issue 175's could work. Neither choice is likely to make a huge difference.RetroG said:I'm 5'11 1/2". My inseam is 32". Currently on the roadbike I have 170mm cranks. I would like to move up to 172.5 for the leverage. Any problem with that? How about 175 as that is what is on the mtb?
I to had 170's on the roadie. With the shorter cranksarms it felt harder to stay on top of a tall gear like i lacked leverage. It also felt like my spin circle ewas to tight. I went to a compact road crankset with 172.5 cranks. It feels alot better.RetroG said:I'm 5'11 1/2". My inseam is 32". Currently on the roadbike I have 170mm cranks. I would like to move up to 172.5 for the leverage. Any problem with that? How about 175 as that is what is on the mtb?
the bigger gear would be easier to "mash" with the increased leverage of the longer crank arm.Mingsta said:I'm not suprised, however shorter cranks should allow you to spin more smoothly in a lower gear.
Long term, this would be better on the knees and hips. Also the guy who takes the spinning classes at my gym (semi pro roadie) says that research shows that you recover faster if you spin a lower gear as opposed to mashing a big gear.