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Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc.
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STers,
I have read all the articles Dan has published over the years, most of the articles on the web that I can find and still am at a dilemma of proper crank arm length, but not necessarily how it affects your cycling. I understand how crank arm directly correlates to gearing and hip angle and all that fun information. That's not my question. My question is how does it affect your running? Here's the background.

Like many of you probably, I started riding about 20 years ago on a standard road bike 53/39-172.5 configuration on a sized 54 road bike. Within a year, started triathlons and bought a tri bike shortly thereafter, again with standard 53/39-172.5 configuration and it was a QR Lucero size S/50.5. Fast forward through a number of bikes later, all same configuration, different bike brands(Scott, TREK, Felt, QR, etc), different sizes to modern day flexibility in bike configurations and I made the transition at the advisement of my bike fitters.

I still ride a 53/39 on ALL my road and tri bikes, but have transitioned to 170 cranks on my road bike (54 Felt) and it's very comfortable. I have also transitioned to 165 cranks on my tri bike (54 Felt IA). I really enjoy the flexibility it adds to my hip angle and have found that I needed to lower my saddle significantly to get proper fitting on the tri bike. I'm 5'8" tall and don't recall, but probably a 30"-32" inseam.

Here's the part I need help understanding the science behind it. Cycling wise - things are GREAT! I can't say whether I have lost/gained power, doubt it very seriously. My bike split for an Ironman that I did in 2011 and this year were within 1-2 minutes of each other on a course that was mostly left the exact same. Running is where I begin to question things. I have shifted the second part of this season to focus on my running and only cycle probably twice a week right now. What I am noticing after those bike efforts or even during a brick run, is that my hip flexors and my stride are really shortened. If you remember the running study they did on ST a few years ago after Kona, it showed video analysis of the pro men and women. It showed a clear difference between those with more of a high step and those with a long step. I don't recall their terminology, but it was the basic difference between runners like Rinny and Wellington. My point is, since I'm running much more at the moment, my stride has really gotten back to where it used to be, I tend to high step more and reach further with each step. My speed has returned on the run with numbers I haven't seen in probably 3-4 years. A brick workout today told me that coming off the bike, my stride and hip flexors sort of felt limited in their movement and it took awhile to find that power on the run again. I have been on this 165 setup on my TT bike for almost 3 years now.

So the question that I haven't read or heard ANYONE talk about is: How does a shorter crank affect different types of runners and their gait/stride? I'm starting to question if my 165s are limiting my run or if it is all superficial, weird feeling, and mental games I'm playing.

Thanks for your interest and feedback.
#PrayforTexas
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [tctritexan] [ In reply to ]
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tctritexan wrote:
STers,
I have also transitioned to 165 cranks on my tri bike (54 Felt IA). I really enjoy the flexibility it adds to my hip angle and have found that I needed to lower my saddle significantly to get proper fitting on the tri bike.

My understanding is that with shorter cranks the saddle should be raised, not lowered (because the shorter crank means the pedal is closer to the saddle when it as @ the 6:00 o'clock position -- so if you do not raise the saddle (and especially if you lower it) you will be getting a greater knee angle @ 6:00 -- also, with seat higher you get an even more better hip angle @ 12:00). Maybe your issues could be solved with a proper fit.
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [hugoagogo] [ In reply to ]
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hugoagogo wrote:
tctritexan wrote:
STers,
I have also transitioned to 165 cranks on my tri bike (54 Felt IA). I really enjoy the flexibility it adds to my hip angle and have found that I needed to lower my saddle significantly to get proper fitting on the tri bike.


My understanding is that with shorter cranks the saddle should be raised, not lowered (because the shorter crank means the pedal is closer to the saddle when it as @ the 6:00 o'clock position -- so if you do not raise the saddle (and especially if you lower it) you will be getting a greater knee angle @ 6:00 -- also, with seat higher you get an even more better hip angle @ 12:00). Maybe your issues could be solved with a proper fit.

That was my take-away from the entire post as well - why did he lower his saddle instead of raising it when going to 165's....
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [tctritexan] [ In reply to ]
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Like others have said, when going to shorter cranks.... saddle should be raised.

blog
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [SBRcanuck] [ In reply to ]
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I was having nerve issues that would only go away with a lower saddle. It should be noted that I moved to 165 cranks on a new bike, so when I say I lowered my saddle, that was in comparison to my old tri bikes. So this one is probably a little more aggressive on the front end, but sciatic nerve issues caused me to lower my saddle to the point of relieving the pain in my back/glutes/hamstrings/calves.

all that is gone, but a higher saddle causes it to return rather quickly.
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [tctritexan] [ In reply to ]
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There are some similarities with things you've described and experienced and what I have noticed. I think after I went to shorter cranks that my running "feel" changed a bit too and I attributed to the tightening of glutes and hamstrings. I feel that the shorter cranks and "reach" of my legs, the fact that the circle my legs are cycling is smaller, allowed my hamstrings to not be as stretched as I used to feel them be after a ride. My hamstrings didn't feel as loose with shorter cranks. Obviously, tighter hamstrings lead to many changes in the running stride. Sorry I'm not totally describing this very well, but maybe you can think about your flexibility and draw some of your own conclusions.
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [Russ Brandt] [ In reply to ]
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No...you are describing it perfectly! I have the exact same "feelings", just hard to put into words unless you come from a running background or have at least been running long enough to know the difference.
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [tctritexan] [ In reply to ]
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I think it takes me a little more running off the bike to get the legs feeling like running legs again. Usually not a problem (maybe not optimal for Olympic distance), and actually a pretty good thing for longer races. I have made sure I take things out a little more conservative on the run off the bike so that I'm not trying to work against the flexibility I don't have until I get a good number of steps in before I decide to turn things up a bit.
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Re: Crank Arm Dilemma - Question for your bike fitters, scientists, engineers, coaches, athletes, etc. [tctritexan] [ In reply to ]
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I'm not aware of any research on crank arm length and subsequent running performance (But it could certainly exist).

The Seat Tube angle research can be interpreted as steeper being better for the running transition, especially in the early chosen pace.

Cadence research can also be interpreted as cadence >80 is beneficial compared to 60rpm for subsequent running. If i recall correctly there was no significant difference between 80 and 100rpm on run performance.

Given all that... it probably makes little to no difference.

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I also give Training Advice via http://www.ForeverEndurance.com

The above poster has eschewed traditional employment and is currently undertaking the ill-conceived task of launching his own hardgoods company. Statements are not made on behalf of nor reflective of anything in any manner... unless they're good, then they count.
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