Flash

For those who "fit" the 170 - 172.5 crank range, how did you decide which crank length was best for you? Any difference in feel between the two when on the bike?

I supppose the extra 2.5mm with 172.5 allows for a slightly lower saddle.

I ask this question because I am currently riding 170mm, but have ridden 172.5 in the past and I'm not sure if there's a significant performance advantage of one over the other.

Thanks

late

If you didn't notice a difference there prob isn't one.

datlas 

I highly doubt 2.5mm makes any real difference.

I have 2 bikes, one is 175 and one is 170....and damned if I can feel any significant difference.

botto 

i went with 170 15 years ago, because that was the fashion.

i went with 172.5 3 years ago, because that was the fashion.

SushiJoe

For a while, larger riders were riding 175mm - 180mm. Now there is a trend tending toward 172.5mm even for larger guys. I'm almost 6'4 and have always preferred 172.5mm.

RazorWind

I think I prefer longer cranks. I have a 172.5 on my Cervelo, and I like the feel of it better than my other bike, which has a 170. The one on the Cervelo is considerably nicer and made of carbon fiber, however, so that may have something to do with it as well.

EivlEvo

My fixed gear has 170's and my roadie has 175's (by choice). I can notice a huuuuuuuuuuuuuge difference. When I get on my roadie it feels like my feet are getting thrown out in front of me.

I have the charts of who should be riding what crank arm length if people are that interested.

jack002

The difference is only 2.5mm, 5 if you think about the size circle it makes. Logically, if you are a spinner, go 170, if not, then 172.5. Small difference either way.

I put a crank on a friends bike years ago that made it 170 and 172.5 on the same bike. He said he couldn't feel any difference. Odd.

Jack

Psimet2001 

I notice a difference between 170-172.5-175. I have ridden 170s for years because it was what came on the size bikes that I bought.

I got a 172.5 on my cross bike when I bought it. I noticed a difference immediately, but it was les pronounced once I got my saddle height tweaked in.

Big difference for me is hip strain. I can feel the difference in my hips after a while of riding with them.

I tried 175's on my TT bike I was building this winter. I do NOT like them. It puts a lot of strain on me in a TT position.

Generally I like the feeling of running 172.5's for cross. I will use a 172.5 for TT's as well. I find I tend to churn higher gears when riding cross and TT's and I find that I like the 172.5's when doing that. Just feels like I can churn them a little better in those lower cadence - higher torque applications.

I still like my 170s on my road/compact cranks. Just like them. Don't feel any need to change.

So...there's a difference. Many riders who don't notice subtle changes may not experience a feeling of difference. Many say that 2.5mm isn't much....well it spreads your feet 5mm apart from each other all throughout the pedal stroke and puts your butt closer to your top foot by 2.5mm at the top of the stroke....that's a lot of change to the system.

Don't believe that? Go move your saddle 5mm (1/2cm) and see if you notice a difference.

HAMMER MAN

personally i noticed a difference switching one bike to 170's and my other ride has 172.5
with 170's it is in my mind easier to carry it over the top,pedal stroke and there is no loping type feeling.
with 172.5 has you hit towards the top of the pedal stroke it seems too lope or almost like a hesitation then it pulls on down.

i am going to switch my other bike too 170's just seems easier and more effcient inturning over my gearing. both bikes i run an 11-23

Just seems a cleaner stroke

Psimet2001 

That's the same feeling I get as well. Better description than mine. Like I said I like that when I am grinding a bigger gear though.

bostongarden

I'm a 170 kind of guy...I like to mash and that makes me want something larger, but, with a worn out hip and things working well, I'm hesitant to change...

powpow

170.

5'10 w/ 31.5 inseam.

EivlEvo

Hmm... this is interesting and it begs me to inquire...

I'm riding 175's. I've ridden 175's for on around 8 years. I know all about pedal stroke and all of that, but just the other month while I was doing 1 leg pedaling on the trainer I noticed that the more tired I got, it became harder (obv) to keep a smooth pedal stroke and I would get to a dead spot at the top. I'm wondering if this is a side effect of the workout I just never happened to notice? Or if it's an indication that I should consider ditching my 175s?

Pharmr

I went from 172.5 to 170 and couldn't notice a difference.

KiddSisko

After riding for years and years with the 170mm length (recommended fit for my height), I'm now using 175. I switched when I put together a custom build bike meant for climbing. Previously I had a 170 triple crank with the 30 inner ring and 26 low cassette gear. The low end ratio was perfect for the really steep hills I had been riding on for fitness. Then I put together my current bike with compact 50/34 and as large a rear gear as a short cage derailer could handle (30). Then to match the same low end ratio as what I had on the previous triple crank bike, I opted for the longer crank arms. It was noticably different, but nothing I couldn't get used to.

The climbing experience is what I was mostly curious about. I had read that the longer arms would put more pressure on the knee and hip joints, so I was concerned that it would be a problem, and not a solution to what I was trying to accomplish. For the first few climbs I noticed some additional tenderness here and there, but after a time all that went away and it's been fine ever since. Had I continued to experience pain, I would have switched back to the 170 crank.

I'm currently at a point in my conditioning where I rarely use that lowest gear combination for climbing, so the 175 isn't really necessary. I'm also in the process of configuring a new bike build and haven't decided if I want to keep the 175, or switch to 172.5.

HAMMER MAN

i really don't know.

in my case I have been riding over 30 yrs and i actually started with 165 that came with my first bike, I lived in ca./ventura cty. @ the time 30 yrs and I wanted more leverage for the hills/mtn and I have been riding 172.5 since. I live in texas now and even though not as mountaineous 2 months ago I switched to the 170 and even in my 12-11th cog it is just a cleaner stroke inmo does not seem to have the pause as you hit the top. I run a 53/39-11-23 on both bikes. I personally believe if you more or less have a long femur than a longer crank arm works better as their is no off-set to hip alingment/knee/ankle as you come down to the bottom of the stroke. short femurs, short crank arms just an observation with myself seems to make sense to me

@ 5'10" I have a longer torso/upper body than legs. I have always been a masher and I like ushing hard gears and even withthe 170 crank it feels more natural than the 172.5

rtruectoc

i have had both. prefer the 170's because i feel it helps me achieve a smoother spin

stapfam

For me- A longer crank gives me slower cadence- so 170 on the road bikes and 175's on the MTB. Don't really notice a difference. EXCEPT- for the Bike I use for milage and that has 165's. Cadence on that bike is higher.

Jynx

post it up

Jynx

I switched from 175's to 172.5 and like the 172.5's better.

I have a very short inseam for my height. 72" tall. 80.8cm inseam (you love the consistency of my measurements)

trojanman

I have 2 bikes. One with a 170 crank and one with a 172.5 crank.

There is a noticeable difference.

I prefer the 170 on my flat rides and use a 52 tooth chainring.

For climbs I use the 172.5, and the extra leverage helps. The 53 tooth I use on descents.

I know it doesn't seem like much side by side, but the shorter cranks really do feel different.

Chainring size should add into the equation............

Jerseysbest

The more I ride and the faster I spin, the more I feel the difference between 170 and 172.5. Definitely preferring 170 over 172.5.

I'll keep the longer crank on my touring bike, but will knock down to 170 on my roadies. I have 165 on my fixie's, but that'd probably be too big of a jump on a road bike, and I don't even know if they make good doubles in that length.

leakysieve

a longer crank allows you to put down more torque at the cost of traveling a longer distance. Personally I prefer the longer cranks as I like to hammer my gears rather than spin fast.

Busta Quad

I run 175s on my TT bike and 172.5 on the others. I an definitely feel the difference. As with all things in road cycling, you'll just have to buy some cranksets of each length and figure out what works for you.