Tyre pressures & handling sensitivity?

[sootie]

I think that it depends upon how you ride the bike, A smaller bike ridden by an aggressive rider would be sensitive to pressures, but the same bike ridden as a daily commuter would barley have any difference. On my little cruiser, 5lb fin the front lower than 28lb, and it handles like crap, front feels like it wants to roll across the road. Not nice on wet roads. My XS11 on the other hand, being a heavy bike, is very sensitive to pressures, too hard and its fucking awfull, wants to follow every grove in the road, too soft, and it fels like it wants to lie down in corners. eeek!. I check the pressures every time I fill her up, or if she has been sitting in the shed for more than 2 weeks between rides.
Tire pressures are important no matter what size bike you ride, big, small, sports or cruiser. Its what keeps you upright on the road. Find that sweet spot for your riding style, starting from the manufactures recommended pressure, and adjust up or down to find your zone.

I am basing my statement on my own experiences, but I have only recently started to think about it from a general point of view. My little 150cc scooter (as mentioned) does not seem to care much 20 to 40psi what the tyre pressure is. Sure you can feel that difference, but the handling difference is small.

If I halve the tyre pressures on my ZZR1100 the bloody thing is horrible to ride, particularly at low speed (I would say unsafe actually). You can notice quite an improvement after 30 minutes or so of riding with low tyre pressures. This is entirely predictable. If the tyres go from say 10 to 40 degC then assuming the usual gas laws the pressure would increase about 10% & an improvement should be noticeable - & it is.

I am afraid I do not see how the way you ride affects the basic stability of the bike itself in any way??
(It would affect safety issues though!!)
Actually, I don't quite follow where you are at here, as you also say:
"My XS11 on the other hand, being a heavy bike, is very sensitive to pressures"
(This seems to be supporting my basic premise here?)

[nodrog:Me]

what sort of air are you using?

[sootie]

what sort of air are you using?

What sort of air would you like me to use?
This is based on the pretty normal Ak suburbs stuff around our way!

[nodrog:Me]

What sort of air would you like me to use?
This is based on the pretty normal Ak suburbs stuff around our way!

Make sure there is no residual whangarei air in there, air from two different climate zones will play havac with your tyres internal barometric atmosphere.

Its actually safer to drain all the air out and refill before every ride. That way you have the correct humidity percentage inside and out, and the tyre will function to its full potential.

[sootie]

Make sure there is no residual whangarei air in there, air from two different climate zones will play havac with your tyres internal barometric atmosphere.

Its actually safer to drain all the air out and refill before every ride. That way you have the correct humidity percentage inside and out, and the tyre will function to its full potential.

Actually, I hear that air from the Chrischurch region is very good too. Same idea as James Bond's Martinis; ie something to do with the air from down that way being shaken rather than stirred.

[bsasuper]

Just put 42 rear 36 front for road use, as recommended by mfr, done

[Maha]

Just put 42 rear 36 front for road use, as recommended by mfr, done

Yes...its not as scientific as some are suggesting, cept nodrog, he knows a thing or two.
My (cold) tyre pressures are on the swingarm, up to 90kg 42 rear and 36 front...done.
May add a few psi if I use a really well packed pack, but other than that....all is good.

[sootie]

Yes...its not as scientific as some are suggesting, cept nodrog, he knows a thing or two.
My (cold) tyre pressures are on the swingarm, up to 90kg 42 rear and 36 front...done.
May add a few psi if I use a really well packed pack, but other than that....all is good.

Yeah; it is handling sensitivity to tyre pressure change that I am banging on about here; not too bothered about the actual pressures used.
(The point about sidewall stiffness is well made though. I would imagine this affects the final sensitivity considerably too.)

I guess high (40+psi) tyre pressues are a function of tyre loading, so maybe the use of high normal operating pressures
is likely to be associated with tyre pressure handling sensitivity.

The point about this being that if a bike uses tyre pressures of more than say 40psi, the tyre pressures should probably be checked more frequently
than those of a bike whose normal recommended tyre pressures are around 33psi (say). This would tie up with my own experience on different bikes,
but others will have a more varied experience here than I have. (Please note use of "probably" in the same sense that more HP = more speed!)