165mm Crank Arms, who rides them?

[quattro]

A recent visit to a cycling PT advised that since I have had a total hip replacement I should switch my 172.5mm crank arms to 165mm.

Wondering if anyone has had experience switching from 172.5mm (or any size) to 165mm arms and how much different it felt and if you like it.

I also have recently been diagnosed with Chondromalacia in my left knee, PT is helping, wondering if the shorter crank arms will also help this issue. I do have some arthritis in the knee, so not sure what the ceiling will be for my rehab, but going in the right direction.

Finally, I have a Cannondale SS with their SiSL2 crankset with 172.5mm arms. IF I can find 165mm arms I can change them and not have to purchase a whole new crankset, not an easy find, and what I have seen is crazy expensive, like $550 just for the arms. Any other crankset option suggestions if I do decide make the jump?

Thanks for your input.
quattro

[pasadena]

I have 165's and 170's
I used 172.5's in the past quite a bit but I think that was a mistake for me.

165s feel great. It's great for position and spinning.
It may or may not be dramatic, but your injuries tell me it may help you.

I'm not familar with Cannondale cranks but for the price, maybe a Shimano or Sram Ultegra/Force crankset would be a value option.
105 even.

good luck on the recovery!

[echappist]

switched from 172.5 to 165 (174 cm with 78 cm inseam) six years ago and haven't looked back. Just make sure to get a lower gear on the back as you'll need to spin more to generate the same power.

Otherwise I like it a lot. More aero, for one thing

[ceolwulf]

Not exactly the same thing but I always ran 165mm on my fixed gear and liked it quite a bit. I didn't find at all that I was short on power or torque due to the crank length. And spinning was easier, and easier on my knees (my right knee is always on the verge of being unhappy for whatever reason). Now on road and gravel bikes I run 170 mostly because 165mm road cranks aren't the easiest to find and 170s work fine for me. I'm 6' and most fitters would have me on a 175 I guess.

[Look585]

165s everywhere for me (5'11", 78cm saddle height). I was struggling bouncing between 165s on the track and 170/172.5s on the road/gravel. Track racing was more important so I converged there. I like them, better spin, more cornering clearance, fewer rock strikes, etc. I've also lowered my gearing to keep cadence a bit higher.

[m_moses]

I switched from 175 to 165 on my road and gravel bikes last year after it was suggested during a Guru bike fit. It has helped alleviate soreness I was feeling in my hip and has not resulted in any loss of power output.

Cannondale SISL cranks are expensive. One of my bikes is a Cannondale Slate 1x with the Hollowgram SL crank arm. I wanted to install a power meter and decided to go with the Stages Cannondale version in 165. My lbs had a matching SL crankset and sold me the right arm for $200.

SRAM cranks can be found pretty easily in 165.


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[loxx0050]

This past summer I switched from 172.5 to 165 on a couple of my bikes (road and TT). Mainly to try and alleviate some knee issues that I developed at the beginning of the year and it's hard to say it helps as I'm still dealing with some pain/discomfort. Went to a PT and it is definitely better but not 100% pain free.

The first few rides felt like I could spin a little higher cadence for hard efforts. Not planning on going back and prefer to keep this setup as it is now. Currently have a SRAM Force 22 crank arms and a Rotor 3D+ crank arms that are 165 (Rotor 3D+ goes all the way down to 150 I believe). Finding a used set of 165's in either of these two is going to be tough. Plenty of other cheap FSA or SRAM Rival ones out there to tide you over until you can get something else a little more bling though.

[m_moses]

To the OP, FYI there are several postings on this topic in the Bike Fit section.


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[harlond]

I'm 5'9" and have 165s on my bikes. I've also had a hip replacement, but I started the move to 165s because I was building up a fixie/SS. I like it for the spinning, haven't noticed any loss of power, but I'm slow to begin with.

[Ralph]

I don't see why you lose anything going to shorter cranks (or gain anything going to longer cranks). Assuming the cranks fit you.

From 172.5 to 165 is a little over 4% shorter. Lets assume everything is proportional....and you lose 4% or so leverage with 165's. Cogs teeth are say 4% to 8% difference on cassette, so if you wind up spinning a gear one tooth bigger usually....don't see how you lose anything.

Most of the tests I have seen suggest crank length (within reason) has little effect on bike speed and power....assuming not a total mismatch of rider to cranks.

I know the math guys will say leverage, tq, power, etc.....are not exactly proportional to crank arm length.....and cog difference (percentage wise) is less with larger cogs than with smaller cogs.....but you get my general point.

[dddd]

Shorter cranks make for a much less critical saddle height adjustment and allow me to get into hard training earlier without knee discomfort.
I've been back and forth with crank lengths ranging from 165 to 175 and can definitely tell the difference, but as far as speed I cannot tell the difference except for when knee discomfort becomes an issue, typically after a rest stop while riding with longer cranks.

165mm crankarms were more common when bikes had toe clips that tended to contact the pavement when the rider was unable to quickly clip in.

[echappist]

Shimano also makes 165mm for at least Dura Ace and Ultegra.

[chengher87]

Am I the only one that rides 165 mm cranks because I am short?

[quattro]

Shimano also makes 165mm for at least Dura Ace and Ultegra.

My Cannondale is full dura ace 9000 except for the Cannondale cranset, which I really would like to keep. So, hopefully I'll find some 165mm arms and will be able to interchange with the 172.5 arms I now have. Still, they seem to be hard to find and expensive.

[carpediemracing]

I am not Cannondale versed nowadays but I think the SISL2 arms are the same as SI arms. If they are you can pick up a set of arms for under $200 and just swap out the 172.5 arms.

[carpediemracing]

I don't have hip or knee issues at this time, although I have very fragile knees. I think that's your biggest thing, to be able to work around your joint issues. However, on the performance side, it's "it depends on the rider".

I have very short legs (67 cm from top of saddle to BB center with Keo/similar pedals). I currently use 175mm cranks. I tried three years (different years - 2008, 2011, 2015) to return to 170mm cranks because of the whole "short crank arm" thing. However I had dismal results consistently with the 170s, even after almost a year on the cranks (2008, 2011). When I switched back to the 175s I immediately, and I mean within one race, saw differences with the longer cranks.

The "depends on the rider" thing is that I tend to do very short, very punchy efforts. I'm talking very short, like a quarter pedal revolution little punch to close a minor gap, literally a snappy half downstroke. Since my metric is "racing" and I'm pretty bad aerobically I have to be very efficient on the bike. The longer cranks make it possible for me to draft more efficiently because I'm a fast twitch kind of rider and the longer cranks let me coast a lot more because one little snap on the pedals can earn me shelter for many seconds. With shorter cranks I have to exert more power (albeit over a smaller distance) or do a couple efforts (two snappy downstrokes) which starts to tax my aerobic system.

I'm also faster in the sprint with longer cranks in my older age, although I was fastest with 167.5s overall. The 167.5s I used 30 years ago and I was unable to finish races consistently so I rarely got to use my sprint in anger - I was faster in training rides but mostly DNFed. When I went to 170 cranks I finished more races although I lost some top end speed. The 175s have earned me consistent top finishes and a slew of field sprint wins but I'm a solid 15-20% slower in maximum speed. There are years where I win almost every field sprint I contest on the 175s, and on the 170s I was struggling to finish the same races.

[gallant]

My bike fitter recommended I switch to 165 cranks during my last fit. So far so good. I tend to be more of a spinner than masher so I don’t mind having to spin more for the same effect.


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[marciero]

I don't have hip or knee issues at this time, although I have very fragile knees. I think that's your biggest thing, to be able to work around your joint issues. However, on the performance side, it's "it depends on the rider".

I have very short legs (67 cm from top of saddle to BB center with Keo/similar pedals). I currently use 175mm cranks. I tried three years (different years - 2008, 2011, 2015) to return to 170mm cranks because of the whole "short crank arm" thing. However I had dismal results consistently with the 170s, even after almost a year on the cranks (2008, 2011). When I switched back to the 175s I immediately, and I mean within one race, saw differences with the longer cranks.

The "depends on the rider" thing is that I tend to do very short, very punchy efforts. I'm talking very short, like a quarter pedal revolution little punch to close a minor gap, literally a snappy half downstroke. Since my metric is "racing" and I'm pretty bad aerobically I have to be very efficient on the bike. The longer cranks make it possible for me to draft more efficiently because I'm a fast twitch kind of rider and the longer cranks let me coast a lot more because one little snap on the pedals can earn me shelter for many seconds. With shorter cranks I have to exert more power (albeit over a smaller distance) or do a couple efforts (two snappy downstrokes) which starts to tax my aerobic system.

I'm also faster in the sprint with longer cranks in my older age, although I was fastest with 167.5s overall. The 167.5s I used 30 years ago and I was unable to finish races consistently so I rarely got to use my sprint in anger - I was faster in training rides but mostly DNFed. When I went to 170 cranks I finished more races although I lost some top end speed. The 175s have earned me consistent top finishes and a slew of field sprint wins but I'm a solid 15-20% slower in maximum speed. There are years where I win almost every field sprint I contest on the 175s, and on the 170s I was struggling to finish the same races.

You are certainly very tuned in to your biomechanics. So you are winning sprints on the 175s while at the same time having slower top speed... I assume this is due to your ability to jump and accellerate better? You must be winning these sprints while still accelerating, so at less than top speed. I'd be curious how you would do with a proper lead-out train!

[carpediemracing]

You are certainly very tuned in to your biomechanics. So you are winning sprints on the 175s while at the same time having slower top speed... I assume this is due to your ability to jump and accelerate better? You must be winning these sprints while still accelerating, so at less than top speed. I'd be curious how you would do with a proper lead-out train!

Leadouts... someone said once that I'm like a glass vial of nitroglycerine. I'm very fragile, have to be babied up to the front, not put under too much stress, else I'll explode. But deliver me properly and I can do a good effort. The guy that said that leads me out here (he was on a different team but we're friends). You can see I eased a number of pedal strokes from the line as pedaling harder wouldn't accomplish anything:
https://www.youtube.com/watch?v=VRJrWJ09Mwc

Third person view of same sprint. I ease because the gap to the riders around me means that I won't catch Kyle and no one will catch me:
https://www.youtube.com/watch?v=opy_kecxZAI

And this is about the best leadout clip I'll ever get. Leadout was at about 35 mph into a headwind, I launched as early as I dared to try and catch the break riders ahead of us:
https://www.youtube.com/watch?v=dqrPW4FWyQg

As far as crank length, I learned a lot throughout the years. Has less to do with top speeds (although it helps a bit) and more to do with arriving at the finish with more in the tank.

The short punchy close-gaps thing I learned when I rode a tandem in a regular group ride. I realized I was expecting gaps to close with just a little downstroke punch, but with a 360+ lbs overall bike weight it felt like I was stamping my foot on a step, not on a pedal that moves down. We quickly got shelled as it took us 3-5 pedal strokes to close even smaller gaps. Back on my single/regular bike I noticed that, yes, I do these little stamps to close small gaps (like a few inches or a foot). I'm not strong aerobically so drafting closely is critical and the "pedal stamp" allows me to stay closer while not taxing me aerobically.

I think that stamp thing is why the 175s work better for me, because I can draft closer with less effort compared to the 170s. Less to do with the sprint.

I lost speed over the years. I think the longer cranks actually helped return some of that speed, but my top speed has gradually declined for about 20 years.

The longer cranks do help me overall, I think because it leverages my muscular system vs my aerobic system. If I was better aerobically it might be different.

For bike differences the crank experiments were well controlled since I only changed the arms (not the spider) and the saddle height. For the last three tries on the 170s I had the Cannondale SI cranks that I still have. For saddle height I dropped it 5mm for the 175s. I found that my peak power was about the same, my jump felt better with the short cranks (no proof it was actually better), top speed possibly a bit better on the 170s, but in practice, without isolating just the sprint, I felt much more taxed on the 170s during rides and races. I was closer to the edge, I'd get dropped quicker. My standard test was the local Tues Night races since the same riders show up and it's somewhat predictable. I'd get shelled every week on the 170s, put on the 175s, and literally the next race found myself vying for the win. For a couple of those experiments I put the 170s on over the winter, like Oct-Dec, and I only gave up on them mid summer the following year. I really wanted them to work as the 5mm higher saddle position is more comfortable for me, it felt better to sprint on the 170s, but the reality was that the 175s (and lower saddle position) worked better for me.

[marciero]

Wow-some awesome finales and racing in general. The subtitled commentary is great. Thanks for sharing. I recall linking to some of your videos a while back in a thread on race tactics-"tailgunning" I think. Good to see our own Shovelhead figuring at the pointy end of things. Incidentally, I've raced on that Ninigret course. I used to live just a few miles from there.