Road bike crank arm lenght 172.5 or 175?

Two different types of riding...you may or not want the same crank length. The longer crank offers more leverage which isn't necessarily an advantage for road bikes. High cadence road riding might be more comfortable when spinning a shorter crank.

There really isn't a right or wrong answer; everyone has a different feeling on what works best for them. Besides, the difference between the two lengths mentioned is so subtle that I'd doubt you'd really be able to notice a difference; the circular path of the pedal axle on a 172.5 crank will only be 5mm (less than 1/4") less in diameter than the 175.

At your height/inseam, I'd go with a 170. Regardless, I don't see 2.5mm worth worrying about.

depends on style of riding. but 175 are more common. i'm 6-1 use 175. avg cadence is 95-110. besides if ones got 175 the other should be same. keep stroke length the same.

the version between the two cranks is barely 5 mm. that's no longer very lots. Cranks are measured from the middle of the crank spindle to the middle of the pedal spindle, the arm itself would desire to truly be the comparable length. A shorter crank supply you much less leverage, effectively making it harder to pedal. you may would desire to apply a reasonably decrease kit ratio to compensate. a hundred sixty five mm may be too short for you. in case you climb lots, the longer cranks you have now would desire to truly be extra effective