Lengthening and shortening cranks - Have you ever experimented with changing your crank length?

[Sharky]

If you want to experiment with short cranks, go down to 145mm then you will start noticing the differences you can achieve with your riding style and position.

If you still have any square taper BB's, have a look at SINZ expert cranks. Really solid and around £40, but you have to keep you eye on the websites as they keep going out of stock.

 

[byegad]

170-150=20mm reduction.So needed effort goes up by (20/150)% = 13.3recuring% more pressure on the pedal needed to get the same effect at the back wheel. As my right knee is wearing out that's too much for me. And yes I know I'd be applying the effort over a shorter stroke, so bending the knee to a lower angle.

 

[Sharky]

170-150=20mm reduction.So needed effort goes up by (20/150)% = 13.3recuring% more pressure on the pedal needed to get the same effect at the back wheel. As my right knee is wearing out that's too much for me. And yes I know I'd be applying the effort over a shorter stroke, so bending the knee to a lower angle.

Have a google on "Gain Ratios"

 

[S-Express]

170-150=20mm reduction.So needed effort goes up by (20/150)% = 13.3recuring% more pressure on the pedal needed to get the same effect at the back wheel. As my right knee is wearing out that's too much for me. And yes I know I'd be applying the effort over a shorter stroke, so bending the knee to a lower angle.

Doesn't sound like you've read the study I linked to earlier.

 

[Milzy]

Makes no difference. I have 170's on my road bikes and 175's on the MTB's.

Most people are the other way around. Longer cranks going through rock gardens give you more pedal strikes which can be painful and ruin your pedals. Especially on hardcore MTB's with a very low bottom bracket height.

 

[byegad]

Have a google on "Gain Ratios"

Yes, that's another issue the gain ratio effect means a virtual lifting of the overall ratio with shorter cranks.

 

[Sharky]

Yes, that's another issue the gain ratio effect means a virtual lifting of the overall ratio with shorter cranks.

You just ride a smaller gear and increase cadence to get the same effect.

 

[byegad]

You just ride a smaller gear and increase cadence to get the same effect.

As I'm running 22-34 on a 20" rear wheel now, I'd be interested in how I lower that gear to compensate for a 13% effect.

 

[Ajax Bay]

when I run out of low gears

Get lower gears, then, by fitting a smaller chainwheel.

 

[byegad]

Get lower gears, then, by fitting a smaller chainwheel.

Smaller than 22?

 

[Scoosh]

That's probably enough to make your knees go pop

One of the known 'dangers' of cranking, not spinning, on a 'bent.

Still I know @byegad has done a fair few miles on his 'bents and not, to my knowledge, completely knackered his knees, so I'm prepared to believe whatever he has, it works for him and, given that he can/could drink his cup of tea** while ascending a pretty steep gradient on his trike at <2mph ...

'Science' aside, it does seem to come down to personal preference and riding style - like so much about cycling !


**cup and saucer, naturally ...

 

[byegad]

I have been known to be overtaken by old ladies hobbling up hill with an overloaded shopping trolley! I do rather enjoy the slow hauls up hills, I get to see flowers, bunny wabbits and all sorts of wildlife in hedgerows as I plod up hill. A 12" bottom gear means I can get up any gradient. Eventually!

 

[Deleted member 1258]

On my geared bike different crank lengths feel the same, on my fixed I feel more comfortable when I'm spinning silly RPM down a descent when I'm on a shorter crank, 165 instead of 170. I suspect it would need a big difference in crank length before most people will feel the difference.

 

[ChrisEyles]

I've got 160s on my road bike and 175s on my MTB. There is a very noticeable difference - the 160s feel much better spinning at higher cadences, say 100rpm+ while I tend to find myself holding a lower cadence on the 175s. I personally prefer the feel of the 160s.