Suspension - How and Why's

[Marty MOOSE]

Its better for me off road as during a race its hot. You can see the difference in rebound for instance on the rear this is an easy on to see. The oil is more viscous when colder for sure so it does effect the performance. Didn't know if you were joking about the shock warmer but there is such a thing

As far as kissing all the other I only have eyes for you Huddy

MM

[Hostilemonk]

bloody dirt bike riders - jeez

yep there are shock warmers out there - same as the tyre warmers in concept - however I ran a little experiment with a hair drier on low and an insulated wrap - heated the shock body withinin the spring coils in 5 minutes to about 50c - was interesting to see the rebound.

food for feeding into a non-linear dynamical system perspective of suspension setup!

PS see post 6 this thread for links to oil viscosity chart

Extract from link from post 6
"DO NOT GO BY LABLED OIL WEIGHT! Not only is this a poor way to decide which oil to use, but each manufacturer seems to be on a different scale. For example Maxima RSF 7wt is actually lighter than Spectro 5wt and Silkolene Pro RSF 7.5wt is actually heavier than Showa SS-8 10wt."


"The Viscosity Index is very important in a suspension oil. “The viscosity index (V.I.) of an oil is a number that indicates the effect of temperature changes on the viscosity of the oil. A low V.I. signifies a relatively large change of viscosity with changes of temperature. In other words, the oil becomes extremely thin at high temperatures and extremely thick at low temperatures. On the other hand, a high V.I. signifies relatively little change in viscosity over a wide temperature range.” So specifically with regard to suspension, the greater the VI, the more consistent the damping will be over a large temp change."

Just remebered this link to a chart with the info for more suspension fluid and the centiStoke data MM mentions (@40c)
http://www.pvdwiki.com/index.php?tit...osity-Data.gif

[g0zer]

cool chart i found

[g0zer]

new suspension setup problem for me

what does it mean, when you are using all the rear tyre but still have inch strips of un-used rubber on the front tyre?

i have a couple of odd handling characteristics as well- at lean angle, at low speeds the front occasionally feels as if the front tyre is rolling off the bead for an instant! maybe pressure is too low but it has 32psi cold in it. i think it is trying to tuck under me when it should be nowhere near tucking.

also the bike tends to track in, oversteers if anything and doesnt seem to stand back up (by itself) when powering out of corners.

this is on my 2010 r1 fitted with dunlop D210 which are 120/70 190/55.

[Ozboy]

Thats an interesting point Gozer, I think you're not alone with the unused secton on the front tyre.

I would assume that due to the smaller radius of the front tyre, the contact edge comes around further than on the rear. It must be engineered into its constructon so that there is minimal chance of the front tyre running out of contact point. Which, due to the smaller radius, is easy to accomplish.

Just my 2c

[JamieBlade]

what does it mean, when you are using all the rear tyre but still have inch strips of un-used rubber on the front tyre?

*Precursor - I know absolutely nothing about bike suspension*

Maybe it's because you're drifting the bike into corners, hanging the back out like a pro and therefore keeping the front wheel more upright compared to the back?

[g0zer]

I would assume that due to the smaller radius of the front tyre, the contact edge comes around further than on the rear. It must be engineered into its constructon so that there is minimal chance of the front tyre running out of contact point. Which, due to the smaller radius, is easy to accomplish.

Just my 2c

yeah i am used to thinking the same way, i have never used these dunlops before. maybe its not worth worrying about until i swap the tyres out with a set of diablo's and see if they start wearing a bit better.

i am used to having maybe 5mm of front edge left, but this is nuts literally a full inch of unused rubber somehow the share of traction seems biased to the rear.

[Gangus]

Entry speed is the front chicken strips I thought...

[g0zer]

I would assume that due to the smaller radius of the front tyre, the contact edge comes around further than on the rear.

ive been thnking about this some more

given a bike is fitted with a rear tyre thats wider and lower profile than the front

at the same time you tip the bike over, it is rotated

eg: you tilt the bike 45 degrees over to the left, the bike will point slightly to the right

at the same time you are counter steering and there is a rake angle component

my gut feel is you will use more front tyre the closer rake is to vertical what do you reckon?

so if im not using any front, i swap the rear out for a taller profile (60 profile instead of 55) and see how that goes. that will have the effect of slightly jacking the rear up and steepening rake.

if that isnt enough, then i can start raising the forks through the triples?

[dmack]

nice write up, thanks

[Kodez]

Thanks jules! Awesome thread.