steering shake
 

Hello, when riding +100km/h mij front becomes unstable, like a shake in the steering. I think the suspension needs adjustement, but i don't know where to start. Softer or harder front or rear?
Riding tkc front and rear at 30 psi on road only
Thanks

i found that my tkc`s on my xtx became unstable anyhting from 75MPH
upwards

TKCs can indeed affect the steering feel at speed, but I've found it more of a wobble/weave than a shake though (on a 21" wheel). In my experience, a bit of fiddling with tyre pressures can alleviate this, or rather I should say, move the point at which the wobble starts further up or down the speed range.

When you say shake, do you mean a high pitch rapid twitching or vibration felt through the bars? (Rather than a weave.) Is this oscillation violent or gentle? How worn/old are the tyres?

Could be a multitude of other things, such as: knackered or incorrectly adjusted head race bearings, poor damping (front or rear), unbalanced front/rear ride height, damaged rim, wheel(s) out of balance, loose spokes etc...

it is like Pleiades says, it's more like a wobble/weave. In June I am going for a 3000km road trip with other tires, maybe bettered

I'd probably be inclined in that case to suspect the tyres.

Have a search on here and elsewhere on the web for "TKC80 high speed wobble", and you'll find it's not uncommon...