Crank length thoughts.

[ONETAL]

Happy new year to everyone.

I'm using 165mm cranks presently on my trikes, but thinking of going down to 160mm. I've only got short stubby legs, inseam of 30 inch. Any thoughts and advice would be appreciate it.

Alan.

[Jdsk]

Recent discussion:
viewtopic.php?t=155830

Jonathan

[ONETAL]

I seen that but I thought it was about bicycles and thought trikes would be different for some reason.

[Jdsk]

Are the trikes upright or recumbent?

Thanks

Jonathan

[mark aldridge]

Hello Alan
Welcome to the can of worms!
I ride recumbent trikes and velomobiles with cranks from 155mm to 140mm.
On my uprights I used the industry standard of 175mm based on my height and leg length.
When I moved to my first recumbent trike it was a Windcheetah with a front fairing and needed 155mm cranks to give foot clearance. I was worried that this would have an effect on the power I could put down. No worries, I was spinning a fraction faster but no eurika moment. What was noticeable was there was less steering weave due to the lessening in distance my feet moved through. I installed 155mm cranks as they were available off the shelf.
I then started experimenting with cheap cranks cut down and went as low as 110mm. By trial and error I settled on 140mm as a happy medium.
All I can say is give it a try. As long as you have an axle with square ends you can try out a variety of short and kiddy cranks at minimal cost (they are easily sold on). When you settle on the right length for you then splash out on a lighter better quality set if you want to.
What you must remember is that within reason there is no "right" length and the human body is very accepting of a variety of parameters.
Good luck

[hercule]

I have a variety… two set up as 152mm, one 140mm. Thorn do cranks with a variety of lengths. At first it feels like your feet are moving in tiny circles but then you forget. Pluses for me are that they play to my strength as a spinner rather than a grinder, better ground clearance for my ginormous feet (relative to leg length), better aerodynamics by getting the front of my fairing lower. Negatives? None really though you will probably need to reduce your chainrings by the same factor as you reduce the cranks, but probably allow a bit more at the top end.

The 170mm cranks I have still got on my Kettwiesel seem ludicrously long in comparison (for various reasons it would be much pricier to swap them so I haven’t bothered)

I don’t think you’d really notice a 5mm difference though. You probably will need to be a bit more adventurous!

[ONETAL]

Are the trikes upright or recumbent?

Thanks

Jonathan

Hi Jonathan,
they are recumbents. If I do go to shorter cranks I'll be going back to oval rings. When I could ride uprights I had Rotor q and qxl rings on all of my bikes.

Alan.

[Jdsk]

Thanks, Alan.

There's an interesting observation above from mark aldridge about steering weave.

And that point about the surprising lack of effect of different lengths does seem to be consistent whenever it's studied.

Jonathan

[ONETAL]

Hello Alan
Welcome to the can of worms!
I ride recumbent trikes and velomobiles with cranks from 155mm to 140mm.
On my uprights I used the industry standard of 175mm based on my height and leg length.
When I moved to my first recumbent trike it was a Windcheetah with a front fairing and needed 155mm cranks to give foot clearance. I was worried that this would have an effect on the power I could put down. No worries, I was spinning a fraction faster but no eurika moment. What was noticeable was there was less steering weave due to the lessening in distance my feet moved through. I installed 155mm cranks as they were available off the shelf.
I then started experimenting with cheap cranks cut down and went as low as 110mm. By trial and error I settled on 140mm as a happy medium.
All I can say is give it a try. As long as you have an axle with square ends you can try out a variety of short and kiddy cranks at minimal cost (they are easily sold on). When you settle on the right length for you then splash out on a lighter better quality set if you want to.
What you must remember is that within reason there is no "right" length and the human body is very accepting of a variety of parameters.
Good luck

Hi Mark,
Thanks for the push to shorter cranks, I've just ordered a pair of 150mm cranks and 38t oval ring from China. I'll let you know how I get on with them.
Alan.

[UpWrong]

I have a set of little used Rotor Q oval rings which I probably ought to sell. 30/40/53 teeth I think, so 74/130 BCD.

[Stradageek]

I used this table https://highpath.co.uk/crank-length-calculation/ to reduce my 4'10" wife's cranks to 130mm on her Kettwiesel using crank shorteners. She is a cyclist reborn

I'm still on 170mm cranks but then I do have a 34" inside leg

[ONETAL]

I think I should have mentioned that I'm riding Sram 1x12 set up's, with a 9-50 cassette and a 42t ring.

[ONETAL]

After 4or5 sessions on the turbo and a ride out yesterday using the 50mm cranks and 38t oval chainring. I quite like it, but feels a bit under geared I'm going to try a 40t ring to see if it feels better or to fined out if it is just the shorter cranks and need longer to get used to them.

[Marc]

I have 80cm/31.5" inseam and ride some recumbent trikes and a velomobile for a bit over 105,000km combined. My preferred pedalling cadence is between 90 and 100rpm.

In a recumbent, my knees are fine with 155mm or shorter crank length. With 165mm cranks my knees hurt quite badly after 50km, with 170mm cranks they hurt after about 30km. With an upright and 170mm cranks, my knees never complained.

[Grldtnr]

Is it feasible to just re-drill cranks and cut threads to suit on old or cheap cranksets, before making a buying decision ,and replacing longer cranks.
I am happy ,at the moment with standard set up, but I may find an advantage to go shorter.