Can Air Pressure Make That Much Difference?

All,

This weekend, I went unicycling (I’m a newbie, still learning the basics). I went on Saturday and Sunday. I had been sick for about 2 weeks, so other than one brief outing on last Monday, it was my first time back to the unicycle in a while (more than 2 weeks).

On Saturday, I couldn’t do a thing. In the past I had been riding up to 70 feet sometimes, and I was learning a lot, but I spent 2-3 hours Saturday and I didn’t go more than 2 feet except on 2 occasions. It was frustrating. At the end of the day, I speculated that maybe my tire was low, because it did seem to be giving more than usual, but it was kinda of a “reaching for straws” explanation for myself.

The very next day (yesterday) I put 4 or 5 solid pumps of air in my tire, and I went out for a little over 2 hours, and I had a great day! I went about 70 feet about 30 times or so, I started from more different locations than my habitual mount points, I rode through grass, I powered through a 1-inch sloped crack/rise in the pavement a couple of times … it was a 100% reversal. Uncanny.

Can air pressure make that much of a difference, or is that not usually a factor?

Lewis

Lewis,
tire pressure can certainly have that much of on impact, especially with respect to controlability. You may have to experiment a bit (as you did) to find out what works best for you. The surface you ride on and your type of riding (rolling over obstacles/jumping etc.) will also influence what pressure is “best” (i.e. the best compromise). Check out
http://www.muniac.com/tips.htm#pressure
for a MUni specific tire pressure discussion by John Childs.
With just a little more experience you will adjust the pressure as needed (and/or expect your uni to behave differently with lower/higher pressures).
For unicycling, standard tires are not uncommonly overinflated to pressures 10% (to 50%!) beyond their max rated value.
Keep having fun.
Fred

Tire pressure can make a big difference in how the unicycle feels and how the unicycle behaves. When you’re learning to ride those differences can be like night and day. Find a pressure that works well for you and stick with that pressure while learning. After you learn to ride then you can experiment with different tire pressures to see what feels best for you.

My little blurb on muni tire pressure was for the fat muni tires. That advice does not hold for street/freestyle unicycles. For your standard freestyle unicycle, tire pressures around 60 psi typically work well. At pressures below 50 psi the tire starts to feel real sluggish and harder to maneuver. Most standard unicycle tires are not rated for higher pressures so that means that you have to overinflate the tire beyond its recommended max pressure. My 20" freestyle uni has a high pressure tire (rated to 85 psi) and I usually run about 70 psi in it.

john_childs

On Mon, 28 Jan 2002 15:05:46 +0000 (UTC), Animation
<forum.member@unicyclist.com> wrote:

>Can air pressure make
>that much of a difference, or is that not usually a factor?
It certainly is a factor, but in addition like anyone else you will
have bad days and good days. But don’t worry about the lows - remember
that if there are lows then by definition there must be highs as well.
Conversely, there would be no mountains without valleys, the earth
would just be imperceptibly larger.

Klaas Bil
(living the The Netherlands - ha! no mountains)

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“Guantanamo Bay, OPS 2A building 688-6911(b), NIJ”

When you sit on the seat you compress the tire, which makes a contact patch on the riding surface.

The more air you put into the tire the higher the tire pressure, so when you sit on the seat the less you compress the tire. This means your contact patch is smaller. The smaller the contact patch gives you less control/stickiness, but also less friction against the riding surface. Less friction allows you to ride faster with much less effort. Your tire will not act as a shock absorber and your ride will be harsher on your butt. But an air seat can make your ride more enjoyable.

The less air you have in your tire, the larger the contact patch, giving you somewhat more “stickiness” but also more friction between you and the riding surface, making you expend more effort while riding. You’ll have more control. The tire will act as a shock absorber, making your ride more comfortable. There are more advantages for low tire pressure for MUni riding, so check out John Child’s stuff.

So to summarize, to make your uni ride with less effort but will make riding a little harder to control, add more air. To have more control and grip the ground but ride with more effort, let some air out.

For less riding effort you could also change your tire to a narrower tire and change the tread from a knobby to a slick (no tread, bald tire). For more grip in the dirt you can change your tire to a fatter knobby tire.

There are limits. If you let too much air out your rim will pinch your inner tube and cause a flat, and you’ll have to walk home cursing yourself. How little air depends on your tire. If you overinflate, your tire will feel like a rock and make your butt ache with pain every time you go over a bump. You’ll make it home but won’t be able to sit in a chair comfortably for a couple of days.

Listening to your body may be the key. I say to listen to your legs and your butt. If after a ride your legs hurt more than your butt, then add more air. If your butt hurts more than your legs then let some air out. If both hurt equally, then your tire’s just right.

Don_TaiATyahooDOTcoDOTuk, Toronto, Canada

On Tue, 29 Jan 2002 04:15:52 +0000 (UTC), don.tai
<forum.member@unicyclist.com> wrote:
>I say to listen to your legs and your butt.

Thanks for the tip, Don Tai. I followed your advice, and I now know
that my butt makes more noise than my legs. Was that the effect of air
pressure you talked about? :slight_smile:

Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“VLF, 64 Vauxhall Cross, Lybia”