Short Cranks vs Big Cranks, Which is Better?

[bpsmith]

Wait, what? Other factors affect speed apart from cadence? Who knew??!!

...

So it should, by your own definition, also follow that the same process will also deliver a lower effort for the same cadence. In which case, precisely how many watts will you save by extending your crank arms by 10mm?

Then why post replies stating technicalities that are cleverly worded to rubbish the OP, whilst actually adding nothing to the discussion. The OP actually has quite a bit of experience, based on their posts, whilst you don't appear to have as much, based on your replies. You don't appear to be stupid, in any sense, so I don't understand your motivation? Boredom perhaps? Enjoy Devil's Advocate?

As for the second part, the logic does apply as you say. How much saved, or added, power output will clearly be down to the characteristics and dimensions of the rider and what they run to start with surely?

 

[Citius]

The OP actually has quite a bit of experience, based on their posts, whilst you don't appear to have as much, based on your replies.

I have 'just' enough experience to realise that the OP is on a wild goose chase and that you are making claims which you can't back up.

 

[bpsmith]

I have 'just' enough experience to realise that the OP is on a wild goose chase and that you are making claims which you can't back up.

I am not making any claims at all on this one actually. The OP is making claims based on his experience. All I did was comment about you confusing things. Anyway, let's not spoil another thread.

 

[Citius]

I am not making any claims at all on this one actually.

Except this one below, which is the one I asked you to clarify, but you couldn't. But never mind, because I know the answer already...

When you factor in the variable of crank arm length affecting the relative gearing and effort required, you are then able to change the cadence for the same effort.

 

[bpsmith]

Except this one below, which is the one I asked you to clarify, but you couldn't. But never mind, because I know the answer already...

Sheldon says it all.

http://www.sheldonbrown.com/cranks.htmlI'm

 

[Citius]

er, Sheldon says you don't know what you're talking about...?

And while you're getting over your cognitive dissonance, have a read of this...

http://bicycles.stackexchange.com/q...0mm-172mm-175mm-crank-arm-length-on-road-bike

At the very least, that should tell you that none of this is as simple as you think it is.

 

[bpsmith]

er, Sheldon says you don't know what you're talking about...?

And while you're getting over your cognitive dissonance, have a read of this...

http://bicycles.stackexchange.com/q...0mm-172mm-175mm-crank-arm-length-on-road-bike

At the very least, that should tell you that none of this is as simple as you think it is.

Lifted from the page quoted:

"Yes, if you go to longer cranks without changing any of the other variables, you will have more "leverage", which is another way of saying you'll have a lower effective gear."

Hence being able to change your cadence, for the sane effort, whilst remaining in the same gear as before. That is all I said, as you know.

 

[bpsmith]

Thinking about the Marrin tests quoted above, they only factored in different cranks lengths and didn't test on the road or even adjust saddle and riding position at all.

Similarly, they didn't test aerodynamic gains from adjusting position when using different crank lengths.

Rather flawed really.

 

[Citius]

Do you have a degree in selective reading?

 

[bpsmith]

Do you have a degree in selective reading?

As I said, let's not spoil another thread please!

 

[A.Z.KOETSIER]

I have 'just' enough experience to realise that the OP is on a wild goose chase

Maybe 2.5 or 5mm (165-170-175mm) change is to hard to see reasonable gains or losses with immediate effect, but I have varied my cranks by 35mm (165-200mm) and there are definite merits to both in my own experience.

Finding the one optimal crank length is not my goal. Maybe just a proportional relation of inseam and/or cadence VS crank arm length.

Surely 170mm +/- 5mm(3%) can't be optimal for everyone with rider inseams and natural cadence varying by often 15-20%.

Yes we can all adapt. but thats not why I started this thread.

 

[Citius]

Surely 170mm +/- 5mm(3%) can't be optimal for everyone with rider inseams and natural cadence varying by often 15-20%.

It probably isn't 'optimal' - but the point I'm trying to make is that the advantage of using an 'optimal' crank size is not going to result in any meaningful difference for most people.

 

[A.Z.KOETSIER]

It probably isn't 'optimal' - but the point I'm trying to make is that the advantage of using an 'optimal' crank size is not going to result in any meaningful difference for most people.

True

 

[Andywinds]

Until I joined this site I didn't even know you could purchase different crank arm length!

 

[A.Z.KOETSIER]

Another conspiracy theory is that a riders height in CM is roughly there ideal crank length in MM....could it be that simple

Does explain why cranks are available in 165-180mm and the most common now being 172.5mm moving from 170mm as humans grow ever taller.

https://en.wikipedia.org/wiki/Template:Average_height_around_the_world