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-   -   Contiforce SM front causing instability ( https://www.xt660.com/showthread.php?t=10311)

pauli 12-05-09 13:31
Contiforce SM front causing instability
 
I have just had a Contiforce SM tyre fitted to the front wheel in place of the Ageing and worn out Pirelli but now the bike weaves very badly at 70mph +. Its most prominent after exiting a bend as the bike comes back upright its weaves until I back off.

Previously I had the front Pirelli with a rear Contiforce SM and experienced no weaving at all at any speeds.

I am running the tyres at 30/30 psi.

Anybody else experienced issues with these tyres and overcome them?

CaptMoto 12-05-09 13:38
Pauli you are running too much pressure on a brand new tyre, bring it down to 28psi until the tyre is road worn / bedded in and then inflate gradually up to 30 if that is how you like it.

weeksy 12-05-09 15:40
Why Capt ?

maxwell123455 12-05-09 17:47
28psi, thats nearly flat!! i run my XTR tyres both at 33-35psi. Nevery had any instablity problems at speed be it new or old tyres (well unless you call sliding the rear over cow poo stablity problems):icon_blackeye:

weeksy 12-05-09 18:29
the owners manual specifes 29-30 front and 32-33 rear as standard.

(suprisingly low i thought)

CaptMoto 12-05-09 19:39
Quote:
Originally Posted by weeksy (Post 93547)
Why Capt ?
Because a Supermoto is not a Sportsbike and not a lot of people, (especially tyre mechanics) understand that these bikes are a lot different in traction and torque, the frame design requires that the better stability and handling are achieved with 28-29-30 psi depending on rider's weight. Big lads might need to inflate up to 33psi.

CaptMoto 12-05-09 19:41
Quote:
Originally Posted by maxwell123455 (Post 93573)
28psi, thats nearly flat!! i run my XTR tyres both at 33-35psi. Nevery had any instablity problems at speed be it new or old tyres (well unless you call sliding the rear over cow poo stablity problems):icon_blackeye:
  1. You are a healthy big lad
  2. You are running semi-knobblies and your bike is not a 17in wheeled supermoto.
  3. Your fork is longer than the X

weeksy 12-05-09 19:53
Quote:
Originally Posted by CaptMoto (Post 93589)
Because a Supermoto is not a Sportsbike and not a lot of people, (especially tyre mechanics) understand that these bikes are a lot different in traction and torque, the frame design requires that the better stability and handling are achieved with 28-29-30 psi depending on rider's weight. Big lads might need to inflate up to 33psi.
Sorry, my question must have been phrased badly.

Why would you start at 28 and increase as the tyre wears ?

nein 12-05-09 20:15
Quote:
Originally Posted by weeksy (Post 93581)
the owners manual specifes 29-30 front and 32-33 rear as standard.

(suprisingly low i thought)
This is not low at all because as the Capt explained the XTX is not a sport bike. I never inflate my tyres over 29 psi. I tried those tyres some years ago and did not have the problems you mention. Could you describe the "shaking" in more detail ?

pauli 12-05-09 20:49
Quote:
Originally Posted by nein (Post 93599)
This is not low at all because as the Capt explained the XTX is not a sport bike. I never inflate my tyres over 29 psi. I tried those tyres some years ago and did not have the problems you mention. Could you describe the "shaking" in more detail ?
The best way I can describe is that it feels like the whole bike is pitching from side to side and will keep on doing so until I back off the throttle. It only happens at 70+ and not at all below that no matter how I try and provoke it.

As I said in the original post it seems worse when straightening up after a bend, but also this evening I had a quite nasty one when crossing a white line in the centre of the road at around 75mph.

I will go and get an accurate pressure gauge as I'm using one attached to a cheap Halfords pump at the moment - just in case its reading badly.

driesie 12-05-09 22:49
Could it be that the wheel isn't balanced correctly?
Might be worth going back to the tyre fitter and getting them to check/re-balance?

CaptMoto 12-05-09 23:03
Quote:
Originally Posted by pauli (Post 93605)
The best way I can describe is that it feels like the whole bike is pitching from side to side and will keep on doing so until I back off the throttle. It only happens at 70+ and not at all below that no matter how I try and provoke it.

As I said in the original post it seems worse when straightening up after a bend, but also this evening I had a quite nasty one when crossing a white line in the centre of the road at around 75mph.

I will go and get an accurate pressure gauge as I'm using one attached to a cheap Halfords pump at the moment - just in case its reading badly.
On a lower pressure a brand new and stiff tyre has the chance to bed in properly. Once that natural process of bedding in has occurred, you can then inflate them a bit more to reach your favourite pressure.

Pegaso rider 16-05-09 08:36
It is not the first time i read about weaving with a conti tire, try to get a replacement (with different manufacturing date)from your dealer

Worry Brother 16-05-09 09:12
1. Re-balance the wheel
2. If no good get a replacement. I had the same with a BT016 last year and it turned out to be a fauly tyre in the end.

Just a thought.

Hope you get it sorted

WB

pauli 21-05-09 17:40
Quote:
Originally Posted by Worry Brother (Post 94232)
1. Re-balance the wheel
2. If no good get a replacement. I had the same with a BT016 last year and it turned out to be a fauly tyre in the end.

Just a thought.

Hope you get it sorted

WB
I have settled on 28/28 and seems to have improved matters but I guess the tyre may have bedded in too - however, I am now confused about the balancing.

There are no balance weights on the rim that I can see so does this mean time to get both back and front looked at or just the front?


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