While I was on my lunch break today, I remembered that my uni was in the boot of the car, so I thought I would have a quick half an hour blast around the Marina. When I pulled the uni out, I gave the tyre a squeeze and realised that it was quite soft.
Hmm, time to nip over to Sainsbury’s and make use of their free air pump at the petrol station.
I mounted, and whilst leaning on a post, looked down at the tyre. Boy, that was low! I’m not exactly a twinkle toes, and if I’d gone off a small kerb I may well have punctured the tube with the rim.
Anyway, once at the petrol station, I first checked the tyre pressure.
I run my mountain bike tyres at around 45-50 psi, so I’ll play it safe with the uni and go for 30 psi.
Valve cap back on, and off we go!
What the hell’s going on?
I UPD three times in the first twenty yards.
I am SO wobbly you wouldn’t believe!
It’s like I’ve gone back a month progress wise. I get back to the car but feel very shaky (physically, not emotionally).
I let some air out and go for another spin. Not so bad this time.
A little more air takes me back to around 20 psi and I’m back in my comfort zone.
Now I understand the concept of the lower the tyre pressure, the more the tyre is in contact with the floor, and the higher the pressure the less rubber is in contact with the floor. This is why roadies pump their tyres up to a gazzillion psi.
So what does everyone feel comfortable with here?
Should I gradually increase my psi and work on my skill level, or is there any point and I should leave things as they are?
I Run my trials at 30, my freestyle uni at 45 or 50, I have had both of the tires at extremelow, where I was almost riding on the rim, it was sluggish, but I got used to it quickly. I have also had both of the tires pumped to the max PSI and I like it, I have lots of control, seems faster, turns are sharper, but I like them to be about in the middle, so I can have some boune while jumping around.
If it’s a fat muni tyre, 15psi isn’t that low, at least for off-road. I run mine at somewhere between 15 and 20. For road riding, a higher pressure would be better, for lower rolling resistance.
As for why road cyclists run high pressures, the narrower the tyre the higher pressure you need to support the weight without the tyre squashing too much (because there is a smaller contact patch). Road bikes have narrow tyres (mostly for weight saving and aerodynamics), so have to run very high pressure. I run my road tyres at just over 100psi, mountain bike tyres at about 35-40 (1.9" cross-country tyres on a hard-tail and rough trails - full-sus bikes could probably get away with slightly more) and muni (3") at 17ish.
Reading through the various responses the thread induced, I suspect we relative novices would benefit from some sort of table of recommended pressures produced by the experts here.
Obviously a number of factors are involved: tyre size, wheel size, rider weight, ground conditions and riding style amongst them.
I admit to having little idea (None) of the actual pressure in my tyre. When my thumb makes little impression on it, I go with that. But I am something of a “Sunday Driver” unicyclist, so my knowledge is very limited.
From the original post I would say that my instinct, on going from 2 wheels to one, given similar tyres, would be to double the tyre pressure, rather than the reverse. I would guess few tyres we use are designed for unicycles, and I suspect some of us significantly exceed the manufacturer’s specifications when we use them.
That is a really nice idea, I am newbie, but with ‘knowledge’ of years of mountainb*king…;).
I knew from my two wheel experience where I am feeling comfortable, but I figured out I could not simply transfer it to my muni. The pressure is really connected to the above factors, hence it would be best if these are all known. Everybody could then evaluate for themself the statements postet. So, I am picking up Naomi’s suggestions
tyre size: 3’’
wheel size: 24’’
rider weight: 132 pounds (60 kg)
riding style: muni riding
ground conditions: sandstone, woods with roots
pressure: 15 psi (1 bar)
I know ground conditions is not easy to describe, but I hope I gave you some idea.
For a 3" muni tyre, ridden off-road, a good general starting point is 1psi per 10lbs of rider weight. Then adjust it either way depending on your riding style and the type of trails (if you’re bottoming out, raise the pressure a bit, if you’re bouncing off roots/rocks as you ride over them, lower it a bit). Obviously lower pressure means more rolling resistance, so if it’s a smooth trail you could raise pressure a bit to go faster/save energy.