Handling

[Nobbylad]

Sorry...another handling/wheel alignment/suspension thread

So, sorted my front springs out the other week (courtesy of Flymo - thanks again Mike!) and the difference was immense.

Next up was a new set of boots as the stock tyres (esp. the rear) were well worn and the rear picked up a screw right on the edge of the chicken strip so it couldn't be plugged (just as well as it was so squared off).

Picked the bike up on Saturday, brand new set of Storm ST's and away I went to scrub them in. Only managed about 20 miles (family commitments) so bike never really got used until today for the daily commute (40 miles each way).

Anyway, everything was fine for the first 10mins or so of the journey today. I'm thinking 'Don't go too mad on the bends, no.1 it's early in the journey so they wont be hot and no.2 they're still not scrubbed in'...so I'm taking it easy. Get onto the motorway and give it some beans (to get the tyres warm obviously) and notice that at around 50mph and an indicated 80'ish (so probably around the limit officer), the bike feels very wierd. Is like this on and off for the journey in and then again on the way home. So much so, that I stop (twice) to check the chain, tyre pressures, bolts/nuts thinking that maybe the garage didn't tighten something up right, but everything seems in order.

The only things that I did notice is that the alignment stops aren't at the same position (one side is 2.5 notches, the other just on 2) and the base of the plate with the notches on (on the chain side) isn't flush with the bottom of the swingarm (there's a gap of a few mill - maybe that accounts for the difference in which notch they're on?). The only other thing I noticed tonight (whilst trying to figure out the string method of wheel alignment) is that the bolts on the adjuster plates weren't tight, so much so that one of the plates was a bit loose. Could this be the issue?

To try and explain the handling is difficult....it's like the front wheel is gently swimming from side to side, giving a sensation almost like when you had changed the height of the handlebars on a push bike as a kid and because you weren't very strong, you hadn't tightened the stem nut enough and when you turned sharply, the bars would actually move without turning the wheel and you knew that very soon, you'd be biting pavement.

The difference in the handling from just after the fork springs were done is quite noticeable, but only at certain speeds. There's no discernible wobble under braking etc, just seems to be every so often it feels .... vague ... swimming .... as if the front wheel is about to go west/fall off.

Maybe it's down to some strange paranoia about dodgy mechanics or just that I'm used to riding a bike with tyres so square it only ever really went straight without any effort?

Only other things to note are there are no balancing weights on either wheel now since the tyres were done. I know that once the tyres are changed, they'll balance differently to the other set, but to have no weights on either, could everything really be that balanced?

Again, maybe I'm just being paranoid/over sensitive, but it certainly doesn't feel as 'true' as it did previously?

Thoughts?

[flymo]

You are definately going to notice a major difference when comparing new tyres to the ones you had on. That rear was about as square as I've ever seen on a bike, apart from a sidecar racing outfit that is

Check the tyre pressures are ok to start with. 36 psi front, 42 rear.

The wheel alignment obviously needs to be correct so you may need to adjust this from what you've described. Its not unusual for the adjusters plates to slacken on one side, especially if they havent been tightened once the main axle nut has been torqued up. Just give the loose one a gentle nip up and it should be fine.

The alignment marks should be near enough the same on both sides but dont be too surprised if there is a slight difference, they arent the most accurate of things given that they are a loose fit over the axle.

The most obvious change I can think of is that you've gone from a very square tyre to a good profiled one, that will lift the rear of the bike quite noticeably, making the bike feel less stable or a little twitchy but also making it more responsive to steering input.

If I were you I would give it a while to get used to it before attempting to make adjustments to the handling.

The other thing was the preload settings I mentioned, the new springs were shorter if I remember. You could wind in the fork preload adjusters another notch or two and see how that feels. If it suits you then might be worth making up a new set of fork preload spacer tubes to bring the adjusters back to the mid point again.

Let me know if you need any help.

Hi there, sounds quite odd to me but i would suggest that maybe your not used to the feel of the new tyres, or that they are not scrubbed in yet and the oil in the tyre as its fairly new is making it feel unstable?

James

[yorkie_chris]

Get some straight edges to check the alignment.
I use 33-36 on the storms.

[Bibio]

yup 33/36 for the storms...

i had the exact same symptom when i got mine fitted... for some strange reason the front storms show a weird shimmy, like its going on and off a ridge (left then right so on and so on)... i discovered that the lower rear shokky bolt was in the wrong way round after i done the shokky swap, fixed this but problem still persisted. the culprate was my front suspension was to soft (mainly rebound) stiffened it up a little and it went away.. BTW mine was at 80-87mph on a private road... below that speed and it was fine, above that speed and it was fine... at around 80mph it was a nightmare.

Went from a square and old road attack (Ie 4mm tread on edges, none in centre) to a new one and found the bike wasn't as happy to stay bolt upright so it's likely just you being on a new rounded tyre.

What about balancing? If the tyres have just been swapped then the adhesive on the weights may not have bonded and fallen off. Worth a check.

[Nobbylad]

Cheers guys, I checked the pressures on my way home last night and they were 30 front/40 rear so I changed them to 33/36 as per spec.

I wound the preload down another notch last night so will give that a go tomorrow/Thursday (am in London today).

I did notice on my first run with the new tyres that they tipped the bike into corners more readily, but as you say Mike, it took effort previously due to the squareness of the rear!

Thanks again for the tips, I'll give it a few more days before taking in to have wheel alignment/balancing checked.

[flymo]

Originally Posted by yorkie_chris

I use 33-36 on the storms.

+1, thanks for the correction. Confirmed these from the Avon website.

Yeah 33-36 for Avon Storms here too!.
Make sure you check tyre pressures when they are cold as they will change even after a short run.
Sounds very strange that there are no balance weights on there at all. I think might have something to do with it.
But like you said check everything else first before hand.