When I present or teach on this topic...I start by asking the class where crank length even came from...what made, 170 or 172.5 or 175 standard crank length options? (originally, most likely penny farthing bikes).


I've personally put many world class triathletes on short cranks (or at least short for what we'd consider normal...165-167.5) I've only had professional cyclist switch back after going shorter...mainly due to their lack of adaptation to their TT bikes (don't spend enough time on the bike) or tradition gets in their heads. The research will show that you're free to choose whatever crank length you'd like within a fairly large window without it impacting you're ability to generate power. It's not to say that one crank length is better than the other, but it's a tool available to an athlete to improve or fix any fit related issues.

I can come up with as many examples of athletes successfully using long cranks as I can short cranks.

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Mat Steinmetz

51-SPEEDSHOP.com - instagram - @matsteinmetz - facebook

Results from Tom A's test.

Time = 12:50, Power = 289W, Cadence = 73 rpm, HR = 170bpm Longer cranks - 175mm
Time = 12:50, Power = 286W, Cadence = 84 rpm, HR = 171bpm Shorter cranks - 150mm

So longer or shorter makes no real difference to climbing. The RPM is different - I am guessing that can be changed with gears.

So no reason to think changing to smaller length cranks will affect my ability to climb - no reason to think I will make any real advantages in aero position.

I at least am a bit more informed than I was at the start of the thread!! Still sticking with my current crank length though.

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You still are not willing to give you real name or race results. Why not? Results can show if a persons training, equipment is worth anything.

Yep, I kept my gearing at 16. I could not make 300 watts with the 175's, but can with the 200s. My story has not changed.

Again, give us your real name so we can all go look at your race results.

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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

Yep. Can you give us examples of successful athlete using longer cranks since so many think it is impossible for me to be successful with 200's, when I was not as good on 175's, in the hills.

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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

I did the trying of shorter cranks in the hills compared to my longer cranks. Longer won hands down!!

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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

It is long past time for this myth to die.....the leading cause of "your seat is too high" comments on ST.

A toe-down pedaling motion is often indicative of nothing more than pedaling toe-down.

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Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Dave, in my opinion, if longer cranks work for you and you like them, you don't have to justify their use. I don't have a lot of experience working with athletes who use longer cranks (which the term itself is relative).

One year when I was doing fits at the Trek camp, Johan had almost every athlete using longer cranks on their TT bikes than their road bikes. Many of those athletes performed just fine on their TT bikes even though current logic would have had them on shorter cranks on the TT bikes and longer on the road.

Another good example are TT experts who ride longer cranks on the road and shorter on the track. They appear to ride just fine on either length.

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Mat Steinmetz

51-SPEEDSHOP.com - instagram - @matsteinmetz - facebook

Actually, the cadence is different AS A RESULT of the gearing change, which is done to allow for the same tangential foot speed for a given pedal force.

That's what is being shown in the Average Effective Pedal Force (AEPF) vs. Average Effective Pedal Velocity (AEPV) charts. My leg muscles pushed at the same shortening speed and with the same force in both cases. They were just doing it at a slightly faster repetition rate, which the study linked to by mauricemaher above in post 116 shows there's no effect on metabolic cost over a wide range of repetition ranges (i.e. cadence).

Cadence is a DEPENDENT variable folks, not an independent one ;-)




I don't think I'd make that assumption...if the shorter length allows you to be just 5mm lower with your bars relative to the saddle, that can potentially have a fairly large effect on your positional drag. I've seen with my own position as much as 15-20W higher drag just for having my bars 5mm too high...above and below that "breakpoint", not much change with bar height. So, if you happen to be just above that type of situation...

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http://bikeblather.blogspot.com/

So, not only do you confirm you don't truly understand the relationship between gearing and leverage, but you also "double-down" by confirming you're bigoted as well...nice.

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http://bikeblather.blogspot.com/

OK. has the long / short crank debate died a death now?? Seems we have come to the conclusion that if its anywhere between 145 and 200mm in length you are good to go??

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And that is the point! Use what you like. BUT, since most folks are short, to say us taller folks are nuts to use longer cranks, is well, ... I continue to say the the 170-175 ARE longer cranks for shorter folks, they just do not know it.

And, SO SO few folks have ever really tried, for any length of time, different size cranks. I HAVE.

And, unless you are riding lots of hills, you would not see any real difference on the flats, as I really saw nothing on flat courses.

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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

I've found that if fore/aft positioning of the seat and bars is held constant relative to the pedal in the 3 O'clock position (parallel to the ground, foot forward), along with the same saddle height at full extension, that it's nearly impossible to "blindly perceive" differences in crank length of +/-5mm (if not more).

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http://bikeblather.blogspot.com/

Dave,

What in the world does my name or race results have to do with anything? Do we need the race results from John Cobb, Robert Chung, Andy Francioni, or Jim Martin to trust their ability to understand the science of measuring aerodynamics or cycling mechanics? I've got a BS in Biology from Cornell where I did physiological testing in cycling with Jim Hartshorn, a masters in science from the University of Rochester. You seem to define yourself by your race results and national ranking. Just for grins do a search on your name and "ranking". You brag about it constantly and backhandedly or not so backhandedly put all others down as you're doing in the most recent post. You frequently call others bullies yet you yourself bully every time you put others down by bragging about "kicking their butts" You may enjoy sharing all your personal details with the world but I for one do not.

My concern with you, a supposed engineer by training, is your complete lack of the use of any sort of scientific methodology in your supposed crank length experiment. Even though it's been pointed out to you numerous times that to actually compare different crank lengths you need to use the same gain ratios you've chosen to ignore that incredibly important point and just bulldozed along with "they were terrible for me". You seem to be proud of the fact that you used a 16 cog for testing your max watts with the 220s as well as 175s when you really should have been running about a 20 tooth cog with the 175s. Just for grins, go back and try the 220s with a 12 tooth cog and see how that works out.

So keep bragging about your results and how you'll kick my butt if we raced but please of please consider the science before you pop off as if you're an expert on every topic under the sun.

Rant over,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Who a person really is, and there race results says everything to me. To hide behind a keyboard and talk like you are an expert, well, have fun hiding.

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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

Dave, you should actually review what sciguy wrote. You are a .... bully who has no understanding of science or logic. For the millionth time, race results mean nothing in this type of discussion.

Training and equipment choices can only maximize a person's potential. Genetics, injuries, there are all sorts of factors that can override the best training and equipment choices. Race results tell you who has the best combination of training, equipment, AND physiology on a given day...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

And you tested it WRONG! You lowered your seat when you went shorter..... which is WRONG! You are suppose to RAISE your seat, move it back, and move the bars back and raise them when you go to shorter cranks. And to top it all off, you didn't change your gearing. You made a significant change (25 mm) change which makes a big difference in gearing ratio. If you didn't do the above, you did it wrong and aren't comparing apples to apples.

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blog

Dave, I never claimed to be the ultimate expert but I have at least put in the time to educate myself while you'd rather not be bothered. Also found lurking at the 1st LA Aero thing were Jim Martin, Jim@EROsports, Jim Felt a complete brain trust from Specialized and of course Andy Francioni of Alphamatis fame who ran the show.

3 Wise Men: LA Aero Thing 1 Quote | Reply

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I was just looking through some pics of our LA Aero "Thing" 1 and thought you might enjoy this one. Shot right in front of the Cycling Canada equipment locker at the VELO Sports Center, too.

Left to right, Hugh "sciguy" Mason, Robert Chung, and John Cobb:

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AndyF
http://alphamantis.com
#findyouraero

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Genetics load the gun, lifestyle pulls the trigger.

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Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

A question for the learned amongst us!! If I go from 172.5mm to 167.5 or 165mm how much should I reduce my gearing to maintain ratios? Currently run a standard 53-39/11-28.

Also, how much further back should my saddle and handlebars be move to maintain position? Assuming I raise my saddle height 5 - 7.5mm

Tom A does an excellent job describing his thoughts on the matter.

http://forum.slowtwitch.com/...post=3581833#3581833

For gearing decisions you can turn to Sheldon Brown's calculator and work on obtaining similar gain ratios.
http://www.sheldonbrown.com/gears/

or just look at the % difference you've changed you crank length i.e. ~ 2.8% for a .50cm change moving from 172.5 to 167.5 making the 28 cog with the 167.5 have ~ the same gain ratio as a 27 cog with the 172.5. So if you're climbing everything easily with your 28 then you still may be fine using it with your 167.5s. If the 28 is at all marginal with your 172.5s you will either want to bump to a 30 or 32 for the large cog on your cassette or swap out to compact cranks.
Moving to the 165s is a change of 4.3% so more like being in 26.7 tooth cog gain ratio wise.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Thanks, I'll take a closure look at those tomorrow!

I've been playing about with setup on my new standard road bike today and with stem slammed, my back is pretty much flat when on the hoods with flat forearms. And I actually find the position pretty comfortable for prolonged periods when spinning easy and it's looks bloody aero (in the mirror anyway!!!!). Problem comes when I increase the power, it's becomes uncomfortable in and around tops of thighs/hip flexors, and isn't easy to maintain.

Ideally I'd like to get this position to work for me, and my current thoughts are, I'll try and achieve this by using a shorter crank, and given its largely been shown power is not significantly effected by crank length, this should all be good!?

I'd imagine I'll need to lower my gearing a bit for the events I'm planing for, so I'll investigate the new shorter crank being a compact setup. Any thoughts on a 52/36 front setup? They seem to run off a 110 spinner, the same as a standard compact does, and the high gear isn't going to be much different to my current setup, but a bit more range at the bottom end!? Although perhaps not enough if I need a 165 or lower!

Hello All:
This is a great thread! It has all the information that rational people need. To summarize:
1) crank length does not influence power
2) crank length does not influence efficiency
3) the length of the crank is just one element in the overall gearing between the foot and the rear tire contact patch
4) shorter cranks may allow a person get closer to horizontal torso position which may improve aerodynamics
But this only helps the rational folks. The irrational folks will believe whatever they want to believe and make arguments to defend those beliefs. Kinda like politics; completely irrational.
Cheers
Jim (5'8" 32.5" inseam with 152.5mm cranks on his tt bike)

And the man himself speaks!

I was thinking "Woah. I'm standing here next to Sciguy and Cobb."

Bio_McGeek was there, too.