Crank length decision

May 5, 15 6:30

Post #1 of 22 (2966 views)

Alright, so I finished my bike trip into the hills. Felt great with the 30lb weight loss. Can't wait to get there next year with another 20lbs gone...

I switched my road bike to a compact crank with shorter crank arms (170mm vs 175) I love the new cranks. I was supposed to take them off and put them on my tri bike but I do not want to, I love them so much on the road bike they are staying on. So I need to order a new crank for my tri bike.

My current thoughts are I should order a 165 for the tri bike, that way in the lower position on the tri bike my hip angle will be closer to the road bike position? Does this make sense?

in case in matters I have been paying attention to my cadence (I removed zeros) and I spin more than I thought. As an example on the last day of the trip with rolling hills and a few medium climbs (2-3km) I averaged 99. On my recovery ride yesterday I averaged 109. On the 2.4km climb at 8% I averaged 294watts and pedaled at 77rpm. I had no lower gear, at 192lbs I was climbing at a VAM of 1010m, if I had a lower gear I would have spun higher...

Hope that helps? Should I bite the bullet and order the 165? My gut says yes.

Last edited by: Triagain2: May 5, 15 9:36

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 6:51

Post #2 of 22 (2939 views)

Congrats on your weight loss!

I switched from 172.5's to 165's last year and have no regrets. You'll never know unless you try.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 6:52

Post #3 of 22 (2939 views)

My thoughts are that crank length is a personal choice so you're not going to get any authoritative answers here. Stick the 170 on the tri bike and see how it feels in your position? If it feels good then don't necessarily feel the need to go even shorter. That said, if you go for the 165 you'll have lots of options available to you if you're willing to chop and change cranks yourself.

I'm a short guy and I'm going from 175 -> 165 because I have trouble getting my foot over the top of the pedal stroke on a 175.

If you stick a 165 on you might find you spin even higher and might want to consider changing gear

Re: Crank length descision [dado0583] [ In reply to ]

May 5, 15 6:55

Post #4 of 22 (2931 views)

dado0583 wrote:

My thoughts are that crank length is a personal choice so you're not going to get any authoritative answers here. Stick the 170 on the tri bike and see how it feels in your position? If it feels good then don't necessarily feel the need to go even shorter. That said, if you go for the 165 you'll have lots of options available to you if you're willing to chop and change cranks yourself.

I'm a short guy and I'm going from 175 -> 165 because I have trouble getting my foot over the top of the pedal stroke on a 175.

If you stick a 165 on you might find you spin even higher and might want to consider changing gear

What do you mean by this last statement?

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 7:00

Post #5 of 22 (2924 views)

Shorter cranks effectively increase your gearing. Read up here.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 7:00

Post #6 of 22 (2923 views)

If you do your recovery ride at 109rpm and switch to 165 you might find that your cadence increases (let's just say 115-120). If this happens you can press the right shifter to shift into a higher gear (increase resistance) so that your cadence goes back to 109, or whatever you deem normal.

When I was on the 165 from 175 my cadence jumped ~10rpm.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 7:03

Post #7 of 22 (2919 views)

Triagain2 wrote:

I have been paying attention to my cadence (I removed zeros) and I spin more than I thought. As an example on the last day of the trip with rolling hills and a few medium climbs (2-3km) I averaged 99. On my recovery ride yesterday I averaged 109. .

While grinding at a super low cadence is a mistake many new cyclists make, I've come to the conclusion that the pendulum has swung in the opposite direction with many new cyclists feeling that a really high cadence must be the be all end all. If your goal is to race criteriums then working on your ability to spin 100 plus will likely serve you well. If you're time trialing, not super charged on PEDs and haven't cycled seriously for 10+ years you're probably not doing yourself any great favor spinning up above 90 or perhaps a bit less. Brett Sutton my be a bit off the wall on somethings but I think he's got it right in regards to triathlete's optimal cadence.

YMMV,

Hugh

Genetics load the gun, lifestyle pulls the trigger.

Last edited by: sciguy: May 5, 15 7:06

Re: Crank length descision [sciguy] [ In reply to ]

May 5, 15 7:11

Post #8 of 22 (2909 views)

I raced for 10plus years mtb"ing (with road racing sprinkled in). I typically average around a 90-95 cadence with zeros included for a ride. During my 2x20 workouts this is my typical cadence. From analyzing rides last week I have sections of power above 250 watts where my cadence averages between 77 and 100.

When I look at this it seems I really do not have a specific cadence I rides at, it varies with terrain. On recovery rides I spin, purposely.

Re: Crank length descision [sciguy] [ In reply to ]

May 5, 15 7:12

Post #9 of 22 (2907 views)

sciguy wrote:

Triagain2 wrote:

I have been paying attention to my cadence (I removed zeros) and I spin more than I thought. As an example on the last day of the trip with rolling hills and a few medium climbs (2-3km) I averaged 99. On my recovery ride yesterday I averaged 109. .

While grinding at a super low cadence is a mistake many new cyclists make, I've come to the conclusion that the pendulum has swung in the opposite direction with many new cyclists feeling that a really high cadence must be the be all end all. If your goal is to race criteriums then working on your ability to spin 100 plus will likely serve you well. If you're time trialing, not super charged on PEDs and haven't cycled seriously for 10+ years you're probably not doing yourself any great favor spinning up above 90 or perhaps a bit less. Brett Sutton my be a bit off the wall on somethings but I think he's got it right in regards to triathlete's optimal cadence.

YMMV,

Hugh

Agreed. I think it's great to be well trained at both ends of the spectrum- High cadence doesn't wear you out and neither does low. This gives you variability throughout the day and the option to do the opposite of what you've been doing for a while. If you want to low-cadence it up a hill for a bit, you don't suffer, and then if you feel like spinning for a while, you can do that, too.

To do this, just alternate your intervals low and high cadence. You'll end up developing smooth and fast "feel" for the pedals and the ability to put out a lot of low end torque whenever you want.

----------------------------------------------------------
Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com

Re: Crank length descision [dado0583] [ In reply to ]

May 5, 15 7:13

Post #10 of 22 (2906 views)

LOL, I was not sure if you meant "gear" in that manner or as in equipment.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 7:18

Post #11 of 22 (2893 views)

Maybe go get a fitting and have them test out various crank lengths to see how they feel while you are aero. I think that would be money very well spent.

Re: Crank length descision [JoeO] [ In reply to ]

May 5, 15 7:21

Post #12 of 22 (2887 views)

Not an option where I live.

Re: Crank length descision [JoeO] [ In reply to ]

May 5, 15 8:59

Post #13 of 22 (2817 views)

JoeO wrote:

Maybe go get a fitting and have them test out various crank lengths to see how they feel while you are aero. I think that would be money very well spent.

X2 preferably a retul fit.

Mine was eye opening. Everything need adjusting when shortening the cranks. Or the other way around. When I got in the position I felt best the crank length was adjusted accordingly. More complicated than adjusting the seat. Based on what I did shorter cranks on my old bike made a mediocre fit terrible.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 9:08

Post #14 of 22 (2801 views)

I just went back from 175's to 200mm and LOVE THEM in the hills. Will see how they do racing on Sat.

.

Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 9:12

Post #15 of 22 (2793 views)

You took the journey almost exactly to mine. In point of fact i went from 175 to 170 on road and really dialed in my road position to nail hoods/tops/drops very comfortably. Then I took the leap to 165's for tt and it was an epic home run. I ran up to 180's back in the late 80's early 90's. Always fought bike comfort. If you have a power meter it's really nice to verify power gains/loss it was invaluable for me in that change of crank lengths. Most people look at me at 6'1" and can't imagine I run 165's. Just give it a rip.....if it doesn't work you can always unload them!

Re: Crank length descision [tigerpaws] [ In reply to ]

May 5, 15 9:38

Post #16 of 22 (2755 views)

tigerpaws wrote:

You took the journey almost exactly to mine. In point of fact i went from 175 to 170 on road and really dialed in my road position to nail hoods/tops/drops very comfortably. Then I took the leap to 165's for tt and it was an epic home run. I ran up to 180's back in the late 80's early 90's. Always fought bike comfort. If you have a power meter it's really nice to verify power gains/loss it was invaluable for me in that change of crank lengths. Most people look at me at 6'1" and can't imagine I run 165's. Just give it a rip.....if it doesn't work you can always unload them!

This exactly. The change was night and day, absolutely love the new cranks. I will put them on the TT bike and compare feel and power to the road bike, If everything is perfect like on road bike I will leave 170's on. If I feel a little tight at TDC the 165's will be ordered.

Re: Crank length decision [Triagain2] [ In reply to ]

May 5, 15 10:03

Post #17 of 22 (2736 views)

It's only 5mm.

You can go down to 145mm without losing power.

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 10:17

Post #18 of 22 (2720 views)

Triagain2 wrote:

tigerpaws wrote:

You took the journey almost exactly to mine. In point of fact i went from 175 to 170 on road and really dialed in my road position to nail hoods/tops/drops very comfortably. Then I took the leap to 165's for tt and it was an epic home run. I ran up to 180's back in the late 80's early 90's. Always fought bike comfort. If you have a power meter it's really nice to verify power gains/loss it was invaluable for me in that change of crank lengths. Most people look at me at 6'1" and can't imagine I run 165's. Just give it a rip.....if it doesn't work you can always unload them!

This exactly. The change was night and day, absolutely love the new cranks. I will put them on the TT bike and compare feel and power to the road bike, If everything is perfect like on road bike I will leave 170's on. If I feel a little tight at TDC the 165's will be ordered.

http://bikeblather.blogspot.com/2014/07/crank-length-whateverwithin-reason.html

Re: Crank length descision [Triagain2] [ In reply to ]

May 5, 15 11:19

Post #19 of 22 (2647 views)

They can be a great fit tool, shorter cranks. It was truly an easy decision to stay with shorter cranks mentally when I saw my power stayed the same and then adding in how great it felt and the massive aero bump. Won't work out that way for all just gotta try. One weird thing for me was the additional drop I had to add to get comfy with 165's was not linear by a long stretch. I was around 11cm of drop and went 175 to 165. As a result I wanted to ride steeper, a LOT steeper and I ended up freeing up so much tension in my low back b/c my pelvis was now rotating and ended up with 17cm of drop. Was freaky how it happened, lucky I guess. So the small reduction in crank length made me want to get steeper and boom I added about 6.5cm of drop in the end. Had to put a -40* stem on my P3 to get it.

Re: Crank length decision [Triagain2] [ In reply to ]

May 5, 15 11:58

Post #20 of 22 (2612 views)

Triagain2 wrote:

Alright, so I finished my bike trip into the hills. Felt great with the 30lb weight loss. Can't wait to get there next year with another 20lbs gone...

I switched my road bike to a compact crank with shorter crank arms (170mm vs 175) I love the new cranks. I was supposed to take them off and put them on my tri bike but I do not want to, I love them so much on the road bike they are staying on. So I need to order a new crank for my tri bike.

My current thoughts are I should order a 165 for the tri bike, that way in the lower position on the tri bike my hip angle will be closer to the road bike position? Does this make sense?

in case in matters I have been paying attention to my cadence (I removed zeros) and I spin more than I thought. As an example on the last day of the trip with rolling hills and a few medium climbs (2-3km) I averaged 99. On my recovery ride yesterday I averaged 109. On the 2.4km climb at 8% I averaged 294watts and pedaled at 77rpm. I had no lower gear, at 192lbs I was climbing at a VAM of 1010m, if I had a lower gear I would have spun higher...

Hope that helps? Should I bite the bullet and order the 165? My gut says yes.

I'll echo what others have said on short cranks are a fine tool to dial in fit. 165mm shouldn't be a problem, and should be pretty available. One caution--most of the major manufacturers don't go below 165mm so that's kind of the last bus stop, but going shorter is definitely possible:

http://www.slowtwitch.com/...k_Database_2862.html

As far as hip angles btw tri and road bikes--I think you're saying you ride an open hip angle on your roadie and more closed for your tri, and you think they should be better matched to improve comfort? If so, then yes, and I think Slowman's articles on how you fit aboard a tri bike would be good (re)reading. Also, it sounds like one or both of your bikes aren't well setup for your purposes. G'luck -J

----------------------------------------------------------------
Life is tough. But it's tougher when you're stupid. -John Wayne

Re: Crank length descision [dado0583] [ In reply to ]

May 5, 15 12:41

Post #21 of 22 (2580 views)

dado0583 wrote:

If you do your recovery ride at 109rpm and switch to 165 you might find that your cadence increases (let's just say 115-120). If this happens you can press the right shifter to shift into a higher gear (increase resistance) so that your cadence goes back to 109, or whatever you deem normal.

When I was on the 165 from 175 my cadence jumped ~10rpm.

Question, so are you riding faster or just using an easier gear?

<We all know that light travels faster than sound. That's why certain people appear bright until you hear them speak>

Re: Crank length descision [dmacandcheese] [ In reply to ]

May 5, 15 12:54

Post #22 of 22 (2570 views)

Don't know yet. I'm riding the same power at around the same cadence now (took a few sessions to readjust back down to 'normal' cadences). It feels nicer; I'm not kneeing myself in the chest on every pedal stroke.

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