Crank lengths?

[buzzy-beans]

I am new to this hallowed place of cycling knowledge, so please excuse me if I make an absolute asssss of myself by suggesting the following.

Surely crank length is not a matter which is solely concerned with body height but surely leg length and upper/lower leg lengths?

If you take a close read/inspection of the Bike Dynamics web pages, most especially these pages http://bikedynamics.co.uk/kneepain.htm you will read about the importance of crank length.

I am 5' 9" and have short but in my case very powerful legs with a seam length of 30.5".

50 + years ago when I used to compete, my bike was fitted with cranks of 6.5" or 165mm.

So taking into account that excessive knee flex is directly associated with knee pain and are directly related (most especially with us arthritic old'uns), then by altering the gearing slightly whilst having shorter cranks will be better for your body?

BB

 

[Colin_P]

In the not so distant past the best answer would have been a triple up front.

Hang on....
https://www.evanscycles.com/shimano-xtr-m9050-di2-triple-front-derailleur-EV222000

No idea what crankset would be needed.

 

[velovoice]

I am new to this hallowed place of cycling knowledge, so please excuse me if I make an absolute asssss of myself by suggesting the following.

Surely crank length is not a matter which is solely concerned with body height but surely leg length and upper/lower leg lengths?

If you take a close read/inspection of the Bike Dynamics web pages, most especially these pages http://bikedynamics.co.uk/kneepain.htm you will read about the importance of crank length.

I am 5' 9" and have short but in my case very powerful legs with a seam length of 30.5".

50 + years ago when I used to compete, my bike was fitted with cranks of 6.5" or 165mm.

So taking into account that excessive knee flex is directly associated with knee pain are directly related (most especially with us arthritic old'uns), then by altering the gearing slightly whilst having shorter cranks will be better for your body?

BB

Absolutely correct. Most reputable bike fitters will agree with you.

170 was the standard for many years, until the industry started chasing the peloton.

 

[Dirk]

In the not so distant past the best answer would have been a triple up front.

There is no way on earth that I would put a triple chainset on this bike. I'd rather suffer!

 

[Colin_P]

There is no way on earth that I would put a triple chainset on this bike. I'd rather suffer!

Fashion victim, and at your age

 

[Dirk]

Fashion victim, and at your age

That's me.

 

[buzzy-beans]

So what's wrong with a triple?

 

[Colin_P]

So what's wrong with a triple?

Nothing, they solve many gearing issues, it is just that they are currently out of fashion.

 

[buzzy-beans]

Nothing, they solve many gearing issues, it is just that they are currently out of fashion.

Ahhhhhhhhhhhhhhhhh, that dreaded word FASHION.

Thank heaven that throughout my entire life, wife the exception of a Beatle haircut in the early 60's, I have never, ever, been a follower of fashion and when it comes down to personal physical performance I have always very much rowed my own boat of pushing it through the pain barrier!

It is just the same with mobile communications, how many zillions £/$/€/etc. are wasted every year by people throughout the World having to upgrade to the latest 'i' or similar phone when their existing one will perform equally as well.
When it comes to bikes I wouldn't mind betting that for the vast majority of us, a decent 1960's Claud Butler (or Sid Motram in my case) would work just as well as anything new and in fashion these days?

Ready now to be shot down in flames!!

BB

 

[Dirk]

So what's wrong with a triple?

Nothing - but I wouldn't put one on a sub 6.5kg, £3500, carbon road bike with Di2.
I've got one on my steel touring bike and it's just dandy.

 

[buzzy-beans]

Nothing - but I wouldn't put one on a sub 6.5kg, £3500, carbon road bike with Di2.
I've got one on my steel touring bike and it's just dandy.

For heavens sake why not?

Up until chronic spinal arthritis stopped me playing golf I used to play 4 or 5 times a week and loved every second of it. A lot of the people I played with (in fact most golfers I knew) used to always try to have the latest bag and the latest clubs, some of which were costing in excess of £400 per club, none of which made them better golfers! As for me, I kept the same set of irons for nigh on 15 years and my woods were a right old mish mash of kit including a Donnay driver that cost me a thumping £18 brand new none of which stopped me getting down to a 7 handicap.

Cycling is I believe very much like so many other sport past times, for some it is all down to fashion and showing off to others what you can afford, however I am of an all together mindset.

In your case Dirk, if a triple works well on your steel touring bike, then surely it could be like lightning if fitted to your 6.5kg carbon road bike, even if it wasn't fashionable to do so?

BB

 

[Dirk]

If it needs explaining, you will never understand.

 

[Smokin Joe]

Triples have become largely unnecessary as the number of sprockets on the hub have increased to 10 and 11. Using a compact chainset with 50/34 rings you can have a higher gear than most people will ever need combined with a low that will get a standard road bike up any hill without having big gaps between ratios. Triples still have a place on heavily laden touring bikes, and also most recumbents because of the extra weight and the inability to get out of the saddle.

The mountain bike weirdos also seem to like them, but they are a strange lot anyway. Some of them don't even shave their legs, for Christ sake.

 

[ridelover9941]

I

Triples have become largely unnecessary as the number of sprockets on the hub have increased to 10 and 11. Using a compact chainset with 50/34 rings you can have a higher gear than most people will ever need combined with a low that will get a standard road bike up any hill without having big gaps between ratios. Triples still have a place on heavily laden touring bikes, and also most recumbents because of the extra weight and the inability to get out of the saddle.

The mountain bike weirdos also seem to like them, but they are a strange lot anyway. Some of them don't even shave their legs, for Christ sake.

I originally had a triple chain ring set on my road bike but I'm now putting a two chain ring crank on it.

 

[MichaelW2]

Same amount of work surely - smaller force over longer distance vs. larger force over smaller distance. Still small beer though.

It depends if your pedalling force is a variable or a constant. Most human physical outputs are pretty constant although you can improve with training to a new and better constant. If your preferred pedaling force is constant, then bigger circles are more work. If your mechanical cog ratio is constant, then bigger circles at lower force are the same work.
It is pretty easy and convenient to change cogs.