# bad knees with 20" or 24"

Anyone have any advice as to what I should by as a first Unicycle. I have worn
out knees from earlier bike touring days. I am learning on a 16" and this seems
fine, but it is plastic. Is 20" or 24" significantly different as far as the
effort needed. What about getting into simple hills. Seems like a 20" rotates
60 inches in one revolution. That’s a big gear for me when I use 27" on my
mountain bike.

Rod Wylie

Re: bad knees with 20" or 24"

Rod,

Knee problems are found with unicyclists as well. Be sure you have your seat at
its correct height and not too low.

Your assumption about the gearing is not quite correct. To calculate the gearing
comparison between a bike and unicycle you need to calculate the force applied
at the pedal for a given movement of the wheel then you will be able to compare
one with the other. Unicycles are geared by changing the length of the cranks
and hence the force/distance moved ratio.

Roger

``````                        The UK's Unicycle Source
<a href="http://www.unicycle.uk.com/">http://www.unicycle.uk.com/</a>
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----- Original Message ----- From: “Rswylie” <rswylie@aol.com> To:
<unicycling@winternet.com> Sent: Monday, April 09, 2001 7:46 AM Subject: bad
knees with 20" or 24"

> Anyone have any advice as to what I should by as a first Unicycle. I have
worn
> out knees from earlier bike touring days. I am learning on a 16" and this
> seems fine, but it is plastic. Is 20" or 24" significantly different as
far as
> the effort needed. What about getting into simple hills. Seems like a
20"
> rotates 60 inches in one revolution. That’s a big gear for me when I use
27"
> on my mountain bike.
>
>
> Rod Wylie

Re: bad knees with 20" or 24"

Rswylie e\$B\$5\$s\$O=q\$-\$^\$7\$?e(B:
>Anyone have any advice as to what I should by as a first Unicycle. I have worn
>out knees from earlier bike touring days. I am learning on a 16" and this seems
>fine, but it is plastic. Is 20" or 24" significantly different as far as the
>effort needed. What about getting into simple hills. Seems like a 20" rotates
>60 inches in one revolution. That’s a big gear for me when I use 27" on my
>mountain bike.

If you use a 27" on a bike, 16" is way too small. For most adults, unless you
are very short, 24" is a good size. 22" may even be better for learning but is
not easily available.

>
>Rod Wylie
>

Stay on top, Jack Halpern, IUF Vice President Website: http://www.kanji.org

Re: bad knees with 20" or 24"

There is a good analysis of pedal forces for different wheel size and crank
length combinations at http://www.sports-psych.com/muni/wheeland.htm

One thing that is different in pedaling a unicycle than a bike is that on a
unicycle you need to backpedal to maintain balance and slow down. This
backpedaling uses different muscles and puts different stresses on the knee.

To minimize knee stress on a unicycle make sure that the seat is not too low.
Figuring out seat height is very similar to figuring seat height on a bike. Hold
on to a wall and put both heals on the pedals. Pedal a few revolutions while
using the wall for balance. If the seat is too high your hips will rock as you
pedal. You want the seat as high as you can without causing your hips to rock.

20" vs. 24" depends on how you intend to ride. The pedal forces on a 20" with
125mm cranks will be about the same as a 24" with 152mm cranks. But keep in mind
that longer cranks mean that your knees will bend more which can put more strain
on the knee (especially if you have IT band problems).

If you want to cover any distance, walk the dog, etc. a 24" would be better.
If you want to just goof around in a parking lot and practice tricks then
a 20" might be better. For general all round flexibility a 24" is better.

john_childs

>From: rswylie@aol.com (Rswylie)
>
>Anyone have any advice as to what I should by as a first Unicycle. I have worn
>out knees from earlier bike touring days. I am learning on a 16" and this seems
>fine, but it is plastic. Is 20" or 24" significantly different as far as the
>effort needed. What about getting into simple hills. Seems like a 20" rotates
>60 inches in one revolution. That’s a big gear for me when I use 27" on my
>mountain bike.
>