Is Crank Length Important To Professional Cyclists?
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- Опубликовано: 6 сен 2024
- Do pro cyclists crank lengths match up with their body height according to Matt's formula? Matt investigates
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Ex-Professional Cyclist Matt Stephens investigates if the crank lengths being used in the professional peloton are relative to body height.
Matt talks in depth with Adam Hansen (Mr Grand Tour) of Lotto Soudal, who is a finisher of 16 consecutive grand tours. Adam uses 180mm cranks, and justifies his decision.
We would love to know your thoughts on the Crank Debate in the comments below 👇
Watch more on GCN...
Does Crank Length Matter? GCN Does Science 📹 gcn.eu/4y
Does Saddle Height Really Matter? | GCN Does Science 📹 gcn.eu/4z
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Let us know your thoughts on crank length in the comments below! 👇
It is a tricky thing to gauge and calculate, first off yes a good stating point is the height, then comes the weight, how much power you can output and then the most important thing is your riding style because here is how power and torque are calculated:
- Power = Torque x Angular Velocity
This means that simply having a longer crank does no mean higher torque like Adam says, it is also how you apply it, they way you stomp on he pedals, do you ride like Froome at high rpm? then short cranks will benefit as your "engine" will produce more power at higher rpm and less torque, if you're like Quintana or Contador always off the saddle putting as much force on the pedals then it will help generate higher torque at lower rpm. Both these methods will have the same outcome :
Low rpm x High Torque = High rpm x Low Torque (within reason and adequate mathematics)
Conclusion, it is necessary to take into account your riding style, the type of riding you do (TT, climbing, sprinting etc), height, weight crank arm length and these will help the amount of power you can output. It is not the case of you will produce more power but use the geometry of the bike to unleash your full potential.
I am an automotive engineer, this is a similar thing to choosing and designing engines, their configuration and application.
Show less
Global Cycling Network surely your peddling style matters to. If you've got a fast turn over or cadance you'll be better with shorter cranks I'd of though. Didn't wiggins try that out last year
Since I got my first rode bike I was 5 foot 7 and I rode 172.5mm cranks and they have just become the norm for me so I would put it down to your own perception and how you feel and what you think is right which in turn could make you ride faster if you think your bike fits perfectly :)
It is definitely a biomechanics problem, not a physics problem. My rule of thumb is that if I can cycle one legged in comfort for a long time then both seat hight and crank length will be in the ball park. Getting that crank over top is a bugger if you pedal is too high.
As a mechanical engineer, I didn't think it was fair for that one rider to comment on what I know vs a bio-mechanial engineer on suh a subject. As if we are binary and could not possibly know more than what our job description suggests.
Considering gear ratios are involved, I am not convinced that a longer crank arm will benefit you and do think bio-mechanics should come into play when considering crank arm length.
I'm 182cm but I use 165mm cranks. They are much easier on the knees. I've had a few crashes and find I'm back on the bike much sooner with shorter cranks as I don't have to bend my knee so much at the top of the stroke. I also find there's less chance of grounding so corners and especially roundabouts can be taken much quicker.
I am 187.96cm and ride 165 cranks
Technically your hip mobility and hip anatomy would also play a role. In order to run longer cranks, you have to lower your saddle height, which means you need to have more hip flexion when your pedal is at top dead center. Then that brings you to how strong your glutes are because they are the prime movers in extension when you're in deep hip flexion. You could literally talk about it for hours lol.
I have bad hip flexors (tore each of them when I played football) and I ride 165mm cranks at 170cm height because my hip flexors won't extend enough to accommodate longer cranks without pain on longer rides
GazelleOnWheels I'm 6'3" / 190 cm and felt hip pain when I switched from 175 to 172.5 just for the hell of it. You'd think it would be the opposite.
SuperJphambone Man, that sounds like a really painful experience. Do you feel it helps at all if you tilt your pelvis forward and sit more forward like in a TT position?
Zach Bonte That's weird aha. There's probably something funky going on there. So many different factors to consider. You're probably okay with the 172.5 if it doesn't cause you pain. Basically the difference between the two would be that you need to apply more force if riding at the same cadence to keep the same power. I find what helps is usually to set up a camera beside a trainer to see if there's anything going on, etc.
is that why hansen has an extreme low position in bike, just to compensate for his longer cranks??
Sneaky hairstyle change at the end, Matt!
He looks younger now! :)
Also sneaky change of clothes, that Matt surely he forgot to film the last bit. 8D
Pacific Film another laughing fit, so hard his hair fell out
I had to go back to check hair length at first part of the video to that shot at the end. Looks like he went from a 175 down to a 172...
Yeah, I noticed. Nice haircut Matt.
I love this sort of content to be honest 😎
Can GCN do some blind tests on crank length please? Just to see whether you can detect a 2.5mm difference if you ride a lot.
That's the sort of change where I'd expect it to be noticeable, but 2.5mm seems a very minor difference. I'm sure I've ridden 175s and 172.5 but wouldn't be able to tell.
They have a video on that george
George Dando they already have a video on that, look up "gcn does science crank length" and you should find it.
Yes Luciano.....the link above is that video...posted almost 2 hours ago
Darren Green no, they have another video about crank length from a while ago
I’m 6’1” with abnormally long femurs. My first bike came with 165mm cranks and I found myself getting knee pain and raising the saddle so much it was practically coming out of the frame. After switching to a new bike with 175mm cranks the saddle stayed where it’s supposed to be and I’ve been riding pain-free on all my bikes for well over 30 years now.
That point about leverage at the end is missing the point I feel. Sure you get more leverage, but that means your legs need to move more to produce the same speed. It's not the equivalent of getting free watts, it's the equivalent of changing from standard to compact.
ik im late to this but i think his point was you need to put down less torque which would allow you to burn out your legs less. for me moving my legs faster and more is much easier to sustain than muscling threw each crank of the pedals. so this made alot of sense to me
Even later to this, but I don't think the advantage of the crank is anything to do with the gear ratio. It increases the distance between the lowest point of the crank and the highest point, allowing you to flex your leg more fully if you have longer legs. In essence it's distributing the load onto your leg muscles differently by lengthening the part of the stroke you can apply power in, altering the overall pedal stroke.
It does come down to biomechanics unfortunately. It's a case of do you want higher RPM or increased leg speed. And in terms of human efficiency and calorific effort, that's biology.
i love Hansen but unfortunately here I don't think he fully understands the physics. Yes a longer lever arm will give you more torque for the same force at a given RPM but by doing so you are essentially just reducing the gearing. Also for the same RPM a longer crank will require a higher leg speed, which could be less efficient.
I found your last paragraph made much more sense than your first. The former had my mind going round in conflicting circles.
There is one thing that's been omitted and that's sprocket and chainring gearing choice. Surely appropriate choice of gears would help to offset such defficiencies in either potential senario.
There I've done it. I've read through all the comments for this video....now where do I pick up my mechanical engineering degree.
When you're young, fast, and on drugs, it does not matter much how long your cranks are.
Motors do the work.
At least some must be using motors, but they can't use that for a full stage. They still need drugs just to be competitive.
I`d like to see Adam Hansen post career get into component manufacture. I think he would come up with some interesting ideas.
He would probably re-"invent" the 90 degree crank and make up a justification for it.
This comment aged quite well
@@danloubser6133 I have the feeling he`s only just begun.
yeah, you only have to ignore the fact that Adam Hansen messes up high-school physics :D
(yes, power = torque * RPM, but as you increase the crank length (hence increase torque), maintaining the same RPM requires more effort, genius)
theoretically longer crank means a longer lever sp easier to turn the gear but tbh you could use gearing to achieve a similar result, thing is for crit races youd want shorter cranks cos then you could happily pedal around tighter bends without fear of the pedal grounding out on the bend. Ultimately for me price is the issue, there is no way im gonna spend another 100 quid on a new set of cranks just because theyre a little longer.
Surely biomechanics is more important that the leverage from the crank because the torque going to the wheels will vary with the gear you are in?
Yes you're right actually. I don't mean to defame the man, but Adam Hansen might have preferred longer cranks because he is a taller rider, and he just confused that with a new maths formula he just learned. Biomechanics matter more than just the torque the cranks can put out.
Awesome informative content, thanks GCN! And Matt, you nail on it!
Appreciate it! We've done great recent content around crank length on GCN Tech 👉 ruclips.net/video/E4BpxByalKg/видео.html
@@gcn Thnx
I’m 6’ 2” my first true road bike came with 170mm cranks, I switched to 180’s around 1990 and they felt amazing & my 2 current bikes have 180 & 177.5 respectively, to be honest I can’t detect much difference between these two lengths but I tried a demo bike recently with 170’s and the circle felt really small and I didn’t like it at all. I always have to special order the long lengths when I get a new bike though, but it’s worth it to me.
Isn't it all about how high your leg comes up with longer cranks and the hip and (referred) lower back pain that ensues from leg coming up too high?
Pro bike mechanic for 20+yrs.
It's worth thinking about everything in this video plus the latter mentioned riders cadence/pusher of a gear or spinner etc & riders style to determine the individuals correct crank length. From there a formula can be used, it's also worth noting the pro riders comments as a lot of scientific sence is talked about & very relavent on this subject.
Basically don't assume your crank length but see someone with the correct knowledge who will asses you to determine.
A good % of my bike fit customers do ride the incorrect length as this is evident on feedback received from them to my questions plus body measurements, type of riding etc.
To reduce the dead effect between 11-2 clock I use 165mm and I am 5'10. This also reduces pain when trying to put power at 11-2.
Great, now I want to buy new cranks. Thanks a lot GCN
You could do a whole vid on Adam Hansen's bike setup.
6 and a half minutes in: Matt finally gets a fresh haircut :)
Lets just say, that short cranks good for fast&easy spinning, while long has a stomping advantage, it doesn`t generate more power, but gives more time to make a turn on high gear while you out of a saddle. Lever is not the crank at all, lever is your chainring!!!
I have heard Adam interviewed a few times now, he gives a really good explanation for everything and puts a lot of thought into his answers, top bloke!
5'11", 32" inseam = 165mm cranks for me! my hip joints love em and if my joints are happy and I have no pain! That means I can ride farther and fasster!!! Everyone is different and that's why you have to find what works for you!
I don't see how one can separate mechanical engineering from bio mechanical engineering in this case.....the are completely symbiotic in cycling. Leaver length etc is all true but so is the way the body pushes the pedals - femur and tibia length is, to a degree, leaver length!
I'm a very short rider of 160cm but have always used 170 cranks - when i got into cycling 20+ years ago I knew nothing about different lengths and just went with what came with my bike. Not long ago I decided to experiment as common sense said I should be in shorter cranks so I bought some 165 cranks for my road bike. It only took a few rides for me to realise that despite being able to raise my saddle slightly I felt under-powered and my performance for perceived effort was noticeably less. So I'm back on 170s. They're probably too long by any "rules" but it's what I'm used to. Probably the fact I have a low cadence (usually 79-83rpm avg over a ride) is part of the reason. Anyway - 165mm Dura Ace cranks are for sale ;)
I have a 56cm trek madone with 300mm cranks. they drag on the ground and gouge the cement when I pedal but damn they're torquey.
I could listen to Adam Hansen all day. More Adam please
I do hope you're being sarcastic!
Well, I find him a bit difficult to understand.
I've seen a study that proved there is not much difference in power output even with very short crank lenght like 140 mm. The longer leverage does not have so much effect because of gears. I use 155 mm cranks with my recumbent bikes. I feel it's more comfortable. But even with upright bikes, short cranks have some advantages - they are lighter and riders position can be more aero.
But in the end it's all about what do you prefer.
6'1" and I use 153 mm crank arms . Good spin , lots of power, and far nicer to my knees. I use to run 172.5 but age caught up to me.
wow! i am 5 7 ,looking to drop to 160-165, 153 thats low
I've recently just bought a custom bike with 170mm cranks, my previous bike had 172mm cranks and already I'm getting new PBs on segmants I was riding regularly last year.
I'm 5'7" (30" inseam, but not sure about my bone lengths) and have ridden 170mm cranks for years. A few bikes ago, I tried out 172.5mm cranks.....I felt like I was a little more powerful on some climbs, but overall, my hip angle closed a bit due to the lower seat height and my cadence on the flats dropped significantly. I went back to 170mm cranks and was much more comfortable.
That Adam Hansen interview was fascinating! More of that please.
6 foot tall, 160-165mm cranks. This allows me to get more aero while keeping my hip angle open to generate more power. Also my saddle is slightly lower for even further aero improvements.
Hansen's mechanical engineering reply gets it spot on...which is why I (at 175cm tall) use:
165mm cranks on the track bike - high cadence means plenty of torque (plus shorter cranks for the banking)
170mm cranks on the single speed - for commuting so comfort over power
172.5mm on the road and TT bike - lower cadence but more torque transferred to the drivechain
Have contemplated 175mm cranks on the road/TT but feel like they'd be too long, especially if the "magic formula" says I should be on 170s.
Surprised that no one has figured this out yet. This is mainly what sets team Sky apart from the rest. They run specific crank lengths based on the course or strategy. The crank length you choose can significantly impact your power output and most importantly in the TDF, recovery time.
You don't apply torque to the pedals. You apply force to the pedals, and that force multiplied by the crank length is the torque produced at the axle (T=F×r). So the longer the crank length, the more torque produced, however, your rpm would drop due to the greater circumference (2πr).
I am 6'5" or 195cm, I use 172.5, 170 and 175 on my 3 whips. I will say I love them all but the 175 is very new to me and I like it so far
''When it comes to pumping, size really does matter, but bigger isn't necessarily always better. So you might find that if you've got a big one it's quite hard to conceal, and doesn't look particularly pretty either. On the other hand if you've got a smaller one, what you might find no matter how you use it, how long or hard you go at it, it just doesn't get the job done effectively''
Campagnolo used the make 165 - 180 back in the NR days, and where I worked we stocked all sizes. Shimano only offered 165 plus 170 - 175. Once the click shift thing took over, Campagnolo reduced their crank length offerings. Sugino and TA still offer a good range of sizes, although they don't pay anyone to use their stuff. Back in the 70s and 80s the rule was bump up a crank length size for CX and TT events as your cadence was lower. On the track most rode 165 as spinning was preferred over stomping. Pursuiters rode a bit longer cranks than sprinters.
I'm 186cm and ride Rotor3D+ 150mm cranks on my trip set-up. My FTP went up, so did my cadence and my aero position is more aggressive. Loving it.
180cm here. i used to ride 172.5 crankarms, but couldn't get my cadence where i wanted. it always felt like i was pushing a bigger gear and i got tired more often, especially on climbs. dropped down to 170's and my cadence improved, my comfort improved, my climbing improved, and my endurance improved. plus, i got to raise my saddle 2.5mm meaning a bigger saddle to bar drop hence i gained some minor aero advantage also. it really is a matter of comfort and efficiency.
I'm 182cm bought a custom.bike with 170mm cranks normally ride 172 or 175. I find the circle small but my cadence has improved, as my cadence improves so does my issue with getting numb feet..
Probably not for the pros with custom fits and plenty parts options, but for us, enthusiasts, bike fit is also another factor - if you want your knee directly above the pedal spindle at the 3 o'clock position, and the saddle is at the end of the rails, crank length is the limiter..... and nice haircut at the end, Matt
I have not read all the comments, so I don't know if anyone has mentioned this already, but anyway.
Along the travel from the position where the cranks is "pointing up" to where it is "pointing down", your knee produces more power where it is more extended. Therefore, the shorter the crank, the less your knee will bend (because the highest and lowest points are closer), and the longer it will be within optimal "power/angle ratio".
Does this make sense? It does in my head.
Of course, a longer crank produces more leverage, but that is the mechanical side.
The bio-mechanics of the knee, on the other hand...
I'm 182cm and I am really happy with a 165mm crank, because of riding a track bike everywhere when I started cycling. It feels right and I perform better.
With shorter cranks you can spin faster, so you can produce the same amount of power. Also, longer cranks can cause knee pain. I try to slam my stem, but in low position there is not enough space for my legs, I feel that shorter one would be better!
Totally agree crank length is a massive factor in power delivery,yes gears make a difference, But to match the extra free torque from longer cranks you would need to pedal faster in lower gear, thus placing greater demand on the cardiovascular system to match the free torque your getting from longer cranks. No brainer longer cranks rule!
crank lengths and Qfactor are personal choice. My road bike is 172.5 and shimano standard Qfactor, my enduro bike is 175 and narrow Qfactor (bb30), I feel more comfortable sprinting in the 175/bb30. I am 178cm tall. The key question for average user is saddle/feet position. The feeling on the corners may change between crank length cos the feet high over the ground
183cm - 170mm cranks. Prefered over 175mm cranks but yet to try 172.5mm cranks. It's a personal thing and worth trying out a few sizes especially if you're finding any discomfort. You won't get discomfort/injury from cranks that a too short for you.
It's always a trade-off because if you go to a shorter crank your knees won't need to work as much but it will need to work harder. The longer crank will give you more knee flex and leverage. I have a 30 inch inseam and I find 172.5's comfey.
I'm 193 cm (6'4") tall and ride 175 mm cranks - which may actually be quite short for me. However, the length of the crank is also dictated by bottom bracket height. Your cranks can only be so long before you start banging pedals on the ground when pedaling and cornering.
One detail that get's left out often is rider's flexibility and range of motion. Some riders have less range of motion in the TDC portion of the pedal stroke making it harder to set their legs up for the down-stroke of the revolution. Also, the "dead spot" covers more travel on longer cranks which means that sloppy pedal technique is more pronounced on longer cranks.
This is the gist of it! Why are we comparing ourselves to pros when most of us have the flexibility of planks?!
actually pro cyclists aren't all that flexible, they have one of the poorest flexibility amongst pro athletes
This was really interesting. One observation is that if a rider ascribes to biomechanics as their primary guidance, they will likely err on the side of shorter cranks to maintain cadence. Conversely, a rider considering pure mechanics may prefer longer arms for leverage.
What a perfect timing for this video. Just on the market for a new crankset.
I'm 182cm and ride 165mm cranks. Used to ride 170, always felt a bit too long. Bought a brand new bike with 172.5mm cranks and literally could not get the power down. Switched to 165mm and my power output went through the roof (ok not quite, but it was higher and felt much more natural).
Think it's because I have very long lower legs compared to my femurs. EveryBODY's different ;D
I'm 177cm (5'9"-5'10") and I ride 177.5mm on my "climbing" bike and 165mm on my aero bike and TT bike. I have every crank length at my house so I've been testing this topic myself for years. If aero doesn't matter (in a group, climbing, riding easy), long cranks are more comfortable to me. When aero matters and you need to get low, 165mm felts more smooth.
Ever since my XL Surly Moonlander came with 180mm Surly crank arms, I’m totally hooked on longer. I’m only 6ft, barefoot, but am all leg. I’m currently looking to replace my 175mm on my gravel bike with a 9 speed triple 180mm. I might even go with a 185mm, but that’s a couple hundred more dollars. I find I have no problem with spinning at high rpm either.
Adam Hansen seems very intelligent, would be good to have a video of him giving tips for future pro-cyclists. Fascinating to listen to him
I got a 'these go to eleven' vibe from the conversation. If you want to reduce the torque needed to sustain a given power, all you have to do is pick a lower gear.
181cm tall, usually ride 175mm, but one road bike with 172.5 mm [now feels short]. Went out on my fixie without first noting its 165mm. Was miserable. To an extent you adjust all positions[seat ht-fore/aft,stem,drop], to optimize with your bike, and its what you get used to. All set for an experiment with 177.5mm in the spring!
I liked my 165mm cranks because when I was getting in the drops with a really flat back my knees were less likely to come into contact with my chest. That being said I am a short rider at 167cm.
I have the same experience - with 170mm the knees feel like they are slamming my chest, when the bottom stroke is correct. Interestingly, accumulated cycle computer data (over 4 -5 months on 170mm) indicated an immediate 10% increase in average speed over the same routes when I changed to 165mm cranks. Ideally, from formulae I have seen on-line, I believe 162.5 mm cranks would be perfect for me - but wish me luck sourcing them.
@@brucet8817 how much power increases did you get with the 165mm cranks
@@damonbonnett6983 Unfortunately, I didn't have a power meter at that time (it was 2012). So I can't give power data, but I'm confident of the average speed data (from lots of rides over the same comparable routes). Plus, I'm not sure that it is about increase in power, but rather efficiency of pedaling and therefore the ability to go faster for longer. My understanding is that shorter cranks will give less leverage and therefore lower power output in a dead-set sprint - but at the cost of pedaling efficiency over a longer time (but I don't profess to be an expert in these matters - I only took up cycling when my knees made it impossible to continue distance running).
He’s a little mixed up. Yes longer cranks improve torque but they also make it harder to spin a fast cadence bc the circle is bigger. This is not only an issue of feet traveling a longer route around the center but also the feet at a more awkward location on the back and top of the stroke. As he said “power is torque x rpm” so sacrificing rpm hurts overall power too. Auto engineers make decisions like this all the line. Bigger bore and smaller stroke for better rpm or vice versa for better torque. Ironically if your legs are weak relative to your lungs and heart you should go with small cranks. You might think such a person needs the extra leverage but he actually needs to rely on his better cardio and run a high cadence. He’ll be able to generate good power by spinning low torque at a high rpm.
always find Adam Hansen fascinating
AndronicasLion his 13 consecutive Grand tour streak, puts him in the know!
16 consecutive finished GTs currently.
Lots of manufacturers offer cranks sub 170... i am a 5'4" rider and use 165mm cranks as I find them the most comfortable and efficient (for me). I have Sram Force 165 cranks AND Shimano 105 5800 also in 165mm in another bike... most manufacturers do make them, they just never come as OM on any bike and you have to go "after market" to get them as I did.
Manufacturers really should be by default putting 165's on their sub "50" frames. These are short people buying these bikes, stop putting 170's on them.
In the end is a matter of preference or intended use. The riders legs are able to produce a fixed amount of peak power. If you use longer cranks, your cadence will be lower compared to shorter crank in order to produce the same power, and vice versa. Probably, a longer crank is better suited for climbing, were a lower cadence is more common.
Please make a weekly/monthly segment just talking to Hansen, what a knowledge guy! He's just blew that height to crank size theory well out the water using science!
I'm afraid he didn't
Gears offset any difference in leverage (from Cranks) to achieve the same "mechanical" advantage as longer cranks, use an easier gear! Exact same effect.
See @Nick Kukoreko's comment
GCN also agrees with this in another video they did, I will see if I can find it for you
I had a lot of respect for Adam Hansen before this interview. I think he was way off the mark with his comments, as @JBMP pointed out as well as a few others in these comments.
I'm afraid he did.
Switching to a lower gear DOES result in less effort that Adam was referring to as his advantage. It does NOT equate to the same speed difference you are implying. Nick's point (& yours) only address the amount of leverage/force required to turn the cranks a full revolution.
What's not being included in that, is the slightly (VERY slightly) difference in distance traveled for that complete pedal revolution. A smaller gear does not spin the tires the same amount (distance traveled) as a larger gear. One revolution is going to have a "micro" difference regarding the distance, but after adding up 90-110 of them per minute for a few hours, it can make a significant difference.
SO - if I can have increased leverage (meaning less leg strength/torque) required to spin my wheels the same distance (because I was able to stay in the higher gear), then a longer crank is more effective, as Adam said.
@Jeff Englin You are entirely correct in saying a longer crank means greater distance travelled per revolution. This does NOT however mean more leverage. This means a longer pedal stroke. Some riders prefer riding at 90RPM, while some prefer 110RPM, there is no optimal.
Therefore a longer crank does mean more distance per revolution, but this is not the same as leverage. Torque=distance*force. Increasing the sprocket the rider is on increases the torque at the wheel, while increasing the crank length increases the Torque at the crank. Both have the same effect in terms of leverage
Check out Zen Cycles in Colorado - they’ve been making custom length crank sets for years. And you cannot base the crank length on the riders overall height?! Must be based on inseam length - I had a cycling accident that resulted in a bad left knee that can only bend slightly past 90 degrees - so I had to go to a much shorter crank just to allow my knee to pass through the top of the pedal stroke.
From an engineer who models RF.: the answer is simple: we must use basic mathematics and engineering to solve this question. Logic alone does not cut it. It simply boils down to how much power the rider applies AT THE CRANK. Stating the issue this way makes gearing irrelevant (assuming one always uses the right gear to achieve the optimal RPM). There has to be a variable curve of max steady power vs crank length for the average rider. Measure this bio mechanical constant (i.e. average for all riders or for any one rider) and you get your answer. Power is RPM X torque. It only makes sense a longer legged rider can spin bigger circles at the same force and RPM (same force providing higher torque) vs a shorter one. However like everything mathematical, there would be a point of diminishing returns. Hence the peak of the curve must be measured, and this is simply where you want the length to be.
I bought a second hand bike recently and the seller threw in a spare compact chainset along with it. Crank length is 172.5mm compared to the 170mm standard chainset that I normally use. Going to swap the chainset over tomorrow to see how it feels.
i'm 6'0 and use 175mm cranks on my road bike and thats here in the mountains in NC. I'll do several centuries and 100k's a year.
but I much prefer smaller 172 or 170mm on my mountain bikes. when i have the larger cranks on the mountain bike with the lower gearing I don't feel I get the pull I need with larger cranks especially going up climbs. Some mountain bikers claim smaller cranks clear obstacles easier, but Ive never had a problem clearing with 175mm cranks
Thanks for the info guys !
165mm cranks are readily available. I'm a huge 5'6 and have a 105 on winter bike, sram red on summer bike. Both in 165 length, and both were in stock online when I ordered. Good point about leverage... I've tried a 160mm length crank and although I liked the fit of the crank, I found it too difficult on steeper sections, 12% plus, of climbs. That loss of leverage is really noticeable out of the saddle, although, I guess more gears could fix that. Also, yes, it did affect style of riding. The shorter crank required an easier gear selection on the rear and increased cadence to maintain what I could do with the 165mm crank.
Another factor is the longer crank length reduces the seat set back (by the extra length of the crank). Made a big difference to me once on a Giant TCR (I'm 183 cm). I believe the correct crank length depends on the bike geometry and the riders leg dimensions.
Just changed from 175 to 172.5, feeling the difference immediately, much smoother pedalling and much comfortable at high cadence. 181cm height, riding canyon M size frame. Short leg and should ride 167.5 according to the leg formula, normally cadence is 110 and maximum is 140
I'm 1,74m tall, I used to have a crank of 170mm in my first bike, and now I have 172,5mm in my current roadies. Both measures are PERFECTLY usable in all the range, BUT.... the differences exist, although are far from obvious. The 170mm crank favoured me in maintaining high cadences, making it easier to sustain over 120rpm when sprinting or for example going downhill even if I got no more gears. The problem is that I'm tipically not a spinner, but more of a masher in my humble amateur cycling style (I have good strength in my legs but my heart and lungs go to very high frequencies rapidly when doing high rpms). Now, with the 172,5mm cranks I think I got the best of me: I can do my best delivering torque to the cranks in the average-to-low RPMs I'm more confortable to do most of the time, even if sacrificing just that little above 120rpm (that I can't handle for so long time), and I can deal with it now with longer transmission ratios just when I need to get those high speeds (like 52x11 or 53x11).
My best years were on 180mm. Good for cornering, lower centre of gravity, and no need to get out of the saddle out of the corners. Great for rolling a big gear over cobbles. Great for a massive jump from a stalling sprint, and no need to change gear during the sprint (of course in my best days your levers were on the down tube!). I'd go back to them now, except they are hard to get.
Although the force needed is less with longer cranks, you have to move them a further distance so the power phase is longer. Does make some sense as the power is less "peaky".
Always a great watch when I'm watching GCN videos; but I found the information here to be especially useful for me today in my fixed gear endeavors. Cheers!
I was all along using a 170mm length. But Storck Markus himself had asked me to use 172.5mm and i never looked back. Improved my power and riding
if you want a low/slammed/Aero position, don't go with long cranks 180/177.5/ or 175s. that extra 2.5mm could be your knees bumping into your stomach
People will argue until the end of time about this! So many different schools of thought on the mechanical vs the biomechanical science. All I know is; I'm 174.5cms tall, I own 2 TCR's (both the same size) with 170mm cranks on one and 172.5mm cranks on the other, and I feel much more comfortable and efficient on the 170mm cranks and always a little out of place on the 172.5s. I guess it really just comes down to what feels best for the rider?
we use gear changes to make pedaling easier, but if you have more leverage you can pedal a bigger gear with the same relative power. All that being said, efficiency is a different story altogether
Power is a force applied over a distance in a set period of time (P = f*d/time). For a given power, a longer crank length reduces the force needed to push the pedals around (Adam's leverage argument), but it increases the distance that your foot must travel to make each revolution. In the end, from an "efficiency" standpoint, it's a total wash. The Biomechanical engineer would be the only one who could say whether it's better to have a shorter path traveled by the foot at a high force or a longer path at a lower force, and this would certainly depend on the rider's properties (leg length, muscle strength, etc.).
'For relaxing time, make it... Hansen time."
Love this guy's take on cycling.
Longer cranks can make you more aero by dropping the saddle height a bit
My first bike had the standard Campy 170 cranks ( I'm 1.77 m tall ) and I always felt like I was spinning and going nowhere ... it was frustrating... By chance I broke on of the cranks in a sprint, and my mate gave me a set of 175's to use... difference was like night and day, changed everything. Actually went to 177.5 's which were great for going uphill but hard on my lumbar, so went back and been happy with 175's for the past 35 years
If I had anything longer than 165 on my XXS bike I could use the pedal for a kick stand.
Ok, I'm a student of engineering in cambridge. In my opinion you see the formula for the first time in my opinion is inertia but it would be good to see the attached document and a half an alnomny to get to know about the delay and the slope and the rest of the torque is powered and leverage but effort is not made from high quality products but you see mechanical engineering jobs and careers in London and south Africa and the rest of your choice of crank the plan is to provide the following week? So your crank lenght should really confer with the same way as the other variables such as cadence or wind speed of the planed session on the right place in the morning.
Thanks Matt. I always wanted to get an understanding of the effect of crank length and why there are different lengths.
As it turned out this is very individual decision. I'm 187cm lång, my inseam is 87cm and i run 165mm cranks. I used to run on 175mm cranks. A couple of differences; no more sore knees, cadence is averaging 100-110 instead of 80-90 and heartrate is down by 10 bpm. Give it a try, do not accept the "norm" from manufacturers.
My power was slightly better going back2back from 170 to 172.5 - it also felt a little easier to sustain smooth power delivery. seems crazy but I was able to do this back to back with a power meter. Sold the shorter cranks to some TT hipster and kept the rings.. worthwhile test imo.
I really hope that Adam Hansen writes a book after his career. In fact it needs to be a series of books. I will gladly pre-order the whole set now!
The height metric asumes everyones body is perfectly proportional. It should be based, at the very least, on your inseam. Bodies can have longer torso & short legs, and long legs with shorter torso's.
I got stumpy legs. Can't even attempt to ride a "traditional" framed bike
depends on the individual physics of a rider,cadence and what your knees are willing to work
When younger and racing, the emphasis is mostly if not exclusively on the mechanical performance benefit of producing more torque with a longer lever with less energy. When you're older and lot racing, the priority needs to shift to biomechanics and the longest possible lever is not as important...
Im 183cm tall on a 165 crank,smaller circle spun more space for my hips and to breath
The longer the crank the farther the feet need to move. The higher the leg will be when it pushes down. visualize yourself on a leg press machine. The more bunched up you are the less weight that will be lifted. The amount of weight that can be moved goes up when the seat is moved back. Try that some time. Shorter cranks are better.
On a road bike I like 175, especially for climbing out of the saddle just for leverage alone. But on a flat ride I like the shortest possible, my thought being the shorter the radius of the crank the shorter the circumference of the circle the pedal is in. More rpm equals more speed. That's my thought on it anyway
I am 167cm and my physio told me to go to 165 based on the issues with my bike fit. Yet my larger bike has 172.5 and the smaller bike has 170. I feel much less fatigued, and have less pain with the longer cranks.
inside leg measurement is more important as i have very short legs, 685mm (27in) and i am very comfortable on 145mm cranks. i had them modified. I must admit i have huge thighs and need to keep the knee angle open to keep the blood flowing to the lower leg.
My inside leg is 710mm & now use 150mm cranks, wish I had swapped to these many years ago. Up to 25 years ago I was using 170mm, I then started to do some really long distance events so I changed to165mm as I was having some knee & back pain issues. This cleared up the pain issue until 5 years ago when the pain came back, I could dial out 1 by lowering the saddle. The knee,s would start hurting then & vice versa with the saddle higher. About 18 months ago went to 150mm cranks, hardly any lower back pain now. No real difference in power other than when climbing I get less wheel spin, probably due to the more constant torque caused by the smaller TDC dead spot.
'm glad you found the answer to your problem. how did you get your shorter Cranks?
I'm using old Sugino cranks bought from ebay, some are 150mm others are 152mm. I cannot feel the difference between them, which indicate to me that I,m now using the correct length cranks. I have tried modding some Shimano 600 170mm cranks down to 150mm it worked but I didn't quite get the pedal angle correct. They were only slightly out but you could notice it when pedaling, so stopped using them after a couple of weeks. Going to try again but using a better jig to hold the cranks whilst drilling them.
I just founr this if thats of any interest to you
www.cobbcycling.com/product/crankset/