coapman said:
No. Why would you think that? Anyone can put any gears on their bike that they feel they need regardless of the crank length they ride.
No. Why would you think that? Anyone can put any gears on their bike that they feel they need regardless of the crank length they ride.
Ugh, until someone presents a counter argument to my opinion that is persuasive why wouldn't I continue to argue my side? It is not a discussion if someone comes and just declares you wrong. I have actually ridden cranks ranging from 220 mm to 85 mm to see what happens. I like most cranks between 130-145. What is your experience?elapid said:
Hey, I understand that most do not see my point. However, it still is the case that there is zero scientific evidence to support the choices they have made. Hence, I am making the argument that they might want to consider something else and giving my reasons why. You, and everyone else, are free to make whatever choice you feel is best for you based upon whatever evidence works for you. Some, however, might find my argument compelling and be willing to try something different. That possibility seems to bother some of you.
But, if you wish to enter the discussion why don't you actually present an actual argument to an alternative view instead of simply coming here and saying others disagree.
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FrankDay said:
Come on, don't complain about someone not answering questions then give a reply like that, it's massively hypocritical.
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FrankDay said:
I believe this is the point. There is zero scientific evidence to support your choices as well as far as I can see. You need to match the same standard you are expecting of others and it doesn't look like you are.
- Mar 18, 2009
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FrankDay said:
I come on to this sub-section of the forum to learn. I have no professional qualifications or experience to allow me to comment on anything to do with bike design, bike fitting, or bike performance with any authority. I am not entering the discussion because I have nothing to offer the discussion (using the word "discussion" here very loosely for all the aforementioned reasons). Like Oldman, I occasionally visit this thread to see if there is anything more to learn. Like Oldman has stated, nothing has progressed beyond what has been said on the very first page of the very first thread on crank length. You haven't contributed anything other than whinging and whining because no one is listening to you and no one is doing the studies that you want.
Because there yet again is nothing to learn on this thread and because I'm not going to waste my time reading your nonsensical ramblings ad nauseum, I will no doubt give in and visit this page in another 3 months with the full expectation that the same protagonists will be making the same arguments and that there will be nothing new to learn.
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coapman said:
I'm guessing it depends what you mean by gear. The ratio obviously remains the same as does the work required to turn it at the cog. But shortening the length of the crank will mean you have to apply a greater force so it will theoretically result in a lower top speed.
Frank linked an interesting paper on mountain bikers that showed they actually accelerated better with shorter cranks, maybe because the increase in force required allowed them to exert at a more consistent rate over a short time period. Or they may have been under-geared. How this translates to real-world or from mountain to road bikers is anyone's guess.
I wouldn't say there are zero scientific evidence to support my choices. Martin "proved" that power doesn't vary over a wide range of crank lengths and it is a scientific principle that lowering the frontal area of the rider should reduce aerodynamic drag. I admit I cannot prove the benefits of my hypothesis but to say there is zero scientific evidence to support it is simply not true. Doesn't anyone actually read what I post? The Martin data has been mentioned many times. I do try to explain how I have arrived at such a conclusion. Others simply declare me wrong or unable to discuss when I don't come around to their opinion based on who knows what?King Boonen said:
Then, might I suggest that when you return several months from now you refrain from repeating your post, which you have done over and over, making this thread something it shouldn't be, which is about me and not about crank length. Thanks for participating though.elapid said:I come on to this sub-section of the forum to learn. I have no professional qualifications or experience to allow me to comment on anything to do with bike design, bike fitting, or bike performance with any authority. I am not entering the discussion because I have nothing to offer the discussion (using the word "discussion" here very loosely for all the aforementioned reasons). Like Oldman, I occasionally visit this thread to see if there is anything more to learn. Like Oldman has stated, nothing has progressed beyond what has been said on the very first page of the very first thread on crank length. You haven't contributed anything other than whinging and whining because no is listening to you and no one is doing the studies that you want.
Because there yet again is nothing to learn on this thread and because I'm not going to waste my time reading your nonsensical ramblings ad nauseum, I will no doubt give in and visit this page in another 3 months with the full expectation that the same protagonists will be making the same arguments and that there will be nothing new to learn.
Well, it would only result in a lower top speed if the rider were not capable of applying that greater pedal force. Two things though suggest that one can provide a larger pedal force at shorter crank lengths. At the same cadence pedal speed is reduced with shorter cranks. It is easier to apply force to the pedal if it is moving away from you slower. And, longer cranks bend the knee more. As the knee bends more it loses leverage such that the muscles cannot push the feet as hard (can you lift more weight doing a partial squat or full squat?). Shorter cranks reduce the amount the knee bends such that it should be easier to put that extra force on the pedals. A third thing probably comes into play also. The power is the combination of the force on the two pedals. We believe it is easier to unweight on the upstroke when the pedal is moving slower, as occurs with shorter cranks. If one unweights more on the upstroke this is the same as pushing harder on the downstroke.King Boonen said:
- Apr 21, 2009
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FrankDay said:
Simply wrong as per usual. Martin showed as you go to either extreme power drops off.
No one has shown that the lower you go in front the more aerodynamic you are. But then a lack of evidence against your claims is proof of your claims.
No, of course we don't read your posts. We all need a little a little humour in our lives, thanks for providing it.
FrankDay said:
No. Are you surprised though? You have been arguing with yourself here for years.
FrankDay said:
Frank,
Are you collecting data with your Icranks or a Powertap as you ride these various length cranks? There effectiveness for you as an athlete would be substantiated a lot more concretely if you actually were generating some hard data. Liking their "feel" and seeing that they allow you to put out less, as much or more power are worlds apart in terms of illustrating how they influence your performance.
BTW- My petite wife does really enjoy her 155mm cranks and is putting out exactly the same power she did on 170s for all durations tested. That's an example of collecting some actual data.
YMMV,
Hugh
We are trying to collect data but so far it is rudimentary. My own data suggests my power is essentially unchanged between 130 and 180 mm crank lengths (not in the aero position). But, this is a n=1 in a not so serious bike rider. Unfortunately, the iCranks system is not ready for prime-time yet (in that the software is still unavailable for me to use) so that is something to be done in the future. I also need to figure out how to get the iCranks to work with cranks shorter than 145. It would be nice if I could do this data gathering with a metabolic cart so I could look at energy cost per watt at various crank lengths but I do not have that available. It is my intent to first look at how changing crank length changes pedaling technique, as I think that is one of the things that can explain the Martin data (something has to explain it), at least partially.sciguy said:
We are also collecting data from customers who we have convinced to try the experiment. Almost all of them (but not all) within one or two weeks decide they really like shorter cranks (in the 150 range typically) and think they will never go back to longer again. Few have gone much shorter in their testing, at least yet.
One of the problems in my gathering data is, of course, everyone would believe my data gathering to be biased so, if I found support for my views, it would give everyone a reason to discount them. Such an effort would convince hardly anyone. My data gathering is more to help me make solid recommendations to those who ask me what they should do or what to expect rather than trying to convince the masses.
Why someone like Martin didn't do a follow-up study to look at this more closely, especially as it applied to time-trialing, is beyond me. But, he hasn't. With there, apparently, being a lot of interest in this area now I hope some researchers will take this project on. Seems like a fairly easy masters thesis project to me.
Regarding your wife, she also is a n=1 example. But, being petite I would suggest she not be afraid to try in the 130 to 110 length range. I am 6'2" and really ride 130 well and like it. (Edit: if I assume your wife is 5' and optimum crank length is relative based on height (or leg length, etc.) then 5' is 80% of 6'2" If optimum for a 6'2" person is 175, 80% of that is 140. But, I think 175 is not optimum for a 6'2" person. Maybe 150 is. 80% of 150 is 120.) I am now riding 145 but only because that is as short as the iCranks will go. If they could go shorter I would be around 130-135 I am sure as my preferred length.
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FrankDay said:
Amazing comedy.
Not sure how many times this link has been posted which is a nice summary of the topic...
http://www.plan2peak.com/files/32_article_JMartinCrankLengthPedalingTechnique.pdf
That references a study McDaniel (and Martin) did that looks at metabolic cost.
http://www.ncbi.nlm.nih.gov/pubmed/12183473
Then a search on pubmed reveals at least six papers on crank length that Martin is involved in, published as late as 2011.
http://www.ncbi.nlm.nih.gov/pubmed/?term=martin+crank+length
My concern is not the data you present, it is the data you constantly ignore. The data you present is always good for a laugh!
Fergie, you occasionally do post something worthwhile. Unfortunately, you either didn't read any of these links or chose not to enter the discussion with some data in these studies that might be relevant to the discussion. Oh well. I thought this interesting from the above abstract:CoachFergie said:
It would appear that the cost of just making the pedals go around goes up substantially with longer cranks and higher cadences (since pedal speed goes up with both). Therefore, it seems we have some experimental data that can explain (in part) why power doesn't drop with decreasing crank length (to a point, at least). If the metabolic cost of cycling goes down with shorter cranks (because pedal speed is reduced) then that energy savings can be put into providing power to the bicycle, compensating for the lost leverage.
Anyhow, my criticism of Martin remains as he (nor anyone else) has yet to address the obvious issues I see with his original study. Repeat the study with increased power to see if a statistically significant difference in power can be found between 145 and 170 mm cranks. And, repeat the study looking at the effect of crank length on power when upper body position is taken into account comparing standard road position to the aero position.
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FrankDay said:
From Martin's summary of McDaniel...
"Of the remaining 2% variability crank length and pedal rate accounted for 1% or 0.02% of the total".
Again laughable that "Mr Anecdote" wants a study done with more than 16 subjects.
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Is it easier? Thinking about it I reckon I can apply the same force over a range of different pedal speeds fairly easily, particularly at a sensible cadence. We're not talking massive changes in pedal speed here, so this just rings untrue with me. Any studies supporting it?FrankDay said:
Are we talking ATG squats or right-angle? At right angle I can lift as much weight I can doing a partial squat, I would expect a decent bike fit would make sure my knees aren't coming up to my chest.
Again, I'd need proof. My knees seem to work fine over a range with no noticeable difference, I only seem to lose power past the right angle.
I'll try dig it up, but I've only ever seen one study done on this and from what I can remember it showed that doing anything on the upstroke had little to no effect on overall power, this was a study on pulling up on the pedals though. Basically the muscles used are there to lift the weight of the leg and can't be trained to do much more. I'd think pulling up would have a balancing effect but not much else. Anecdotally, on a spinning bike in the gym I have tested my maximum power output with and without straps and there was no difference.
"thinking about it" you conclude you can apply the same force on the pedals regardless of pedal speed. Your conclusion is wrong. The faster the pedals are moving away from you the less force you can apply because the same muscles that apply that force must first be used to accelerate the foot up to the pedal speed before any force can be applied. The highest force can be applied when the pedal is stopped. Zero force can be applied if the pedal is moving faster than you can move your foot.King Boonen said:
ATG or right angle? Does it matter? You can lift as much weight when your knee is at 90º as when it is at 45º or 25º? You are unusual I would suspect. There must be a reason stairs evolved to be 6 to 8 inches high rather than 14" (the height the typical 170mm cranks makes the rider lift the foot).
And, you would think a good bike fit would ensure your knees aren't coming up to your chest? I guess this pro doesn't have a good bike fit. I wonder what change he might be able to make that would move that knee away from the chest while keeping his good aero position?
"seem to work fine" and actually working the same are two different things. Anyhow, something has to explain Martin's findings in which maximum power stayed the same (or slightly increased) as crank length was reduced from 195 to 145 mm in their study.
Doing little and doing nothing are two different things. Failing to unweight completely on the upstroke means doing negative work on the upstroke which diverts power provided by the pushing legs from getting to the wheel because the energy necessary to overcome this deficit must come from somewhere. This is the condition for the vast majority of riders out there. As I said earlier, there is a reason steps have evolved to be only 6-8" high. The effort needed to lift the leg the different heights probably plays a role.
Anyhow, all I was trying to do is explain the Martin findings. Something has to explain why cranks that are way too long or way to short result in reduced power and why there is a wide range of crank length where power hardly changes.
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Prove it.FrankDay said:
The foot is already in contact with the pedal, it's in a clipless shoe with a thin carbon sole bound to the pedal by a cleat. And any extra force required to accelerate the foot that 1mm space between the sole of the foot and the sole of the shoe will then be applied to the pedal.
Hence the reason people have, what are they called again... gears, that's it. As long as there is sufficient resistance the highest force can be applied both stationary and in motion.
Yes it does. different muscles work better at different points in a squat and going ATG removes the quads almost entirely from the first part of the return to standing. Up to 90º it seems pretty much exactly the same.
Probably to do with the fact that people are different heights, have different fitnesses and different flexibility. Regardless, climbing stairs is a different, unsupported movement and I don't really see the relevance here.
This is my fault, I was talking from a standing/upright position. Basically anything allowing the knees to go past 90º maximum.
[/QUOTE]
"seem to work fine" and actually working the same are two different things.
Arguing semantics is silly. If you want it more accurate I'll go out on a limb and say I remember the paper saying there was no statistical difference between lifting and not lifting.
In terms of crank length, my best guess would be that way too long cranks bend the knee past an acceptable tolerance, resulting in decreased power, while way to short ones do not bend it enough, stopping full power being applied.
Within certain tolerances the muscles and joints involved work the same. Not everything has to be linear.
I am simply trying to make an argument as to what I believe to explain the findings. By the same token I can ask you to prove your contention. Neither one of us will be able to do so.King Boonen said:
LOL Yes, the foot is always in contact with the pedal when using clipless pedals. Would it happen if the shoe were sitting on platform pedals? No. That is because that circular motion involves constant acceleration. F=ma. Since the shoe/foot has mass that acceleration cannot occur without an applied force. That force is either going to come from the muscles of that leg of the muscles of the other leg coming through the connected cranks and clip or some combination (the usual case). Yes, the foot is constrained to move in a circle by the pedals but, because the foot in attached to many other components that do not move in a circle that constraint is not "energy neutral" as would be seen in a pure spinning disk (or if the shoes were spinning in the pedals alone, not having a foot in them attached to two legs). There is a reason your HR will go up spinning completly unloaded at high cadences.
What do you mean by "sufficient resistance". It is simply common sense that if the resistance changes this will affect the maximum force that can be applied.
Yes, but the Power lifter is pushing straight down. The cyclist has a more complex question as the direction of the motion is constantly changing. At the top of the stroke the movement is forward (where the glutes, being used by the power lifter in this position, are useless), at the bottom straight backwards. Only at 90º is the motion straight down and then only very transiently.
Go to a gym and look at people on the stair master where they can self select "stair" height and their foot is "constrained". Look what people choose for maximum efficiency/power for sustained power.
Note in that picture the knee is beyond 90º. That movement will be the same whether the torso is up or down.
But, changing crank length changes the crank leverage (isn't that the reason everyone gives as to why longer cranks should be more powerful?). Therefore, if power remains constant over this variation something must be changing in the other components in the opposite direction to compensate for this. That is my point. If you have another explanation to explain this data I am open to hear what it is.
I know the paper you are talking about. It has a lot of problems.
Another web site pushing shorter cranks giving more anecdotal reports. I must admit I am surprised at how short they have been able to get some of their riders to go as we have trouble getting people to even try shorter than 150. Anyhow, here is an excerpt and link
http://www.bikesmithdesign.com/Short_Cranks/cranks4kids.html
http://www.bikesmithdesign.com/Short_Cranks/cranks4kids.html
Some examples, showing power with short cranks;
I have one customer, 6'-2" (188cm) tall, with range of motion issues, competing in long distance Brevets on 95mm cranks. Another gent with range of motion limits is climbing the hills of San Francisco with a single 38t chainring and a 12-25 cassette, also on 95s. Because your legs are straighter, you push harder on the pedals, making up for lost leverage. The fellow in San Francisco bends pedal spindles.
One of my customers, 5'-7" (170cm) tall professional triathlete Courtney Ogden, won the big money 2011 Western Australia Ironman on 145s. The next day, despite being wasted, he ordered a set of 130s. He's done extensive work with the people at PowerCranks where they are becoming big advocates of shorter cranks.
A few years ago a team of 4 Australian MTB racers, ranging in height from 5'10 to 6"1 won a 24 hour MTB race on 125s. With the shorter cranks they rarely had to stand. conserving energy. And they were able to get by with a single chainring because the useful RPM range is so wide with shorties. . The wider useful RPM range is good for kids as they aren't always in the right gear (Unlike us grownups
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FrankDay said:
So more stories and nothing substantial to challenge the data presented by Martin and his team showing no significant advantage to changing crank length.
Hey, Chris Froome spends a lot of time looking at his stem and he won the Tour de France so I suggest we all do that
http://chrisfroomelookingatstems.tumblr.com/
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