What would the advantage be of pushing a 175 instead of a 172.5? I’m 6’1" with 33" inseam…
More torque.
More torque does NOT equal more power, though.
You gain the advantage of a longer lever arm, but the work required to pass through a full revolution is greater (since the circle is longer).
And remember, it is a MINOR difference.
Cyclist who pedal at a low cadence and push a lot of torque anyway usually prefer longer (relatively) cranks. Cyclist who spin very high cadences usually prefer shorter (relatively) cranks. If you have very large/meaty thighs (which often accompanies pushing big torque), then you would want a longer crank, because there is actually a significant metabolic cost associated with moving the weight of one’s leg up and down, especially if your leg is very heavy.
Crank length is a factor of many things. Cadence is a big part of it. There are formula’s that you can use. But really they don’t mean anything. The only way to tell effectively would be to go see a really good fitter, ideally somebody like Andy Pruitt at BCSM, who could tell you whether or not you were getting the most effective muscular usage out of your pedal stroke.
For a while there was a trend towards longer cranks. Now the trend is towards shorter as people tend to spin faster.
If you are very powerful and/or like to pedal more slowly, you would likely benefit from jumping up to 175’s. If you are not very powerful and like to pedal quickly, you are likely best off staying on 172.5.
It is not an exact science.
Yup, I think I’m made for 172.5 but unfortunately the shop put 175 on my bike…said they’d replace them next week but that’s after my half IM…so we’ll see how it goes…
I appreciate your input on this and other threads. How is it you know so much??
I’m 6-3 with long legs (37" inseam). I use 180mm arms on my Tri bikes with Rotor Cranks and Ultegra 175’s on my road bike.
Sounds like you’re a big masher! You seem to know a lot about the Rotors, Zipp. What’s your opinion about my arm length?
This will be my first race on the Rotors…only ridden 3 times thus far on them…uhoh.
Rotors have slowed my cadence while increasing speed, while lowering my heart rate at that speed. I’m much faster on them. I was already using DA 180mm crank arms when I swtiched to Rotors.
At 6-1, sounds like you could try the 175’s. I had no problem spinning 175’s. They just felt to short for me. I tried to go back to 177.5’s after riding 180’s for a year or so and ended up back with the 180’s. 172.5 seems pretty short for a guy your height, but remember, lots of things in cycling are very individual. The only reason I use 175’s on the road bike is all the changes in speeds on group rides. Its hard to wind up the 180’s when its called for in group rides. I like the 180’s as it seems to help hold my speed more consistant on the tri bike.
It’l take a bit longer to get used to the Rotors. I thought I had it all done in about 2-3 weeks…NOT…it took me a few months to get really comfortable with them. After using them for a few weeks I went on a ride on the road bike without them and could barely turn the regular cranks smoothly. I’ve been on them for about 6-8 months now and can swtich back to the regular cranks on the road bike now without any problems at all. Wierd…I know!
Thanks for your input. I’m glad to read you’re very happy with your set-up. I hope I’m soon happy with mine…maybe after the weekend…who knows!
BTW, your inn looks great.
Thanks
.
I’m a “student of the game.”
You can punch me after the race this weekend if you are unhappy with my advice. I’ll be there.
Look for a real, real skinny guy in a TriSports.Com kit. Riding a blue tint & titanium Serotta with HED Stingers…
Hey, you’re coming from NY to Racine? You know what bike I’m riding! I recently sold my Legend Ti…
Returning to NY via Racine actually. I’m coming home from a training camp in British Columbia…
Sweet! I’ll look for you and say hi…I’ll be wearing a blue Sugoi suit…and you probably can’t miss my girlfriend! 
What times you shooting for?
No, that P3C will be hard to miss. The Rotors ought to set her apart… Unless you are talking about a human girlfriend…
The swim course appeared quite short last year. And the run seemed a might short too. It’s a fast course. I’m hoping to give’r and see what happens.
Well, I was talking about my real human GF…but I’m sure you’ll see the P3 too…it’ll be like a target on my back (as my friend say)…
Good luck at the race…sounds like you deserve it!
Thanks, can always use some good luck!
I’ve just gotten used to jokes about “how’s the wife” in reference to my bike from a couple of friends since I seem to be so “committed” to it. 