Sounds like you could be suffering from what’s known as “chatter”- the handlebars feel like they’re jumping about in your hands crossing ripples/ruts in a corner? Google it, there's plenty of info out there and see what the symptoms are and if they're similar to yours.

Often the most common cause of chatter is insufficient rebound damping, although it could be a combination of too much preload or a spring of too higher rate.

The first thing I’d point a finger at is your fork oil. When was it last changed? When was the level/air gap last checked? Is the correct weight of oil in there? If it’s a second hand bike you bought and you haven’t had the forks out, these three questions are going to be pretty impossible to answer.

The addition of extra preload (fork spacers) tends to show up weak rebound damping as, although the springs haven’t changed in rate, they have more stored energy which will be dissipated quicker when they are unloaded, putting the rebound damping under additional strain.

Changing the fork oil and checking the air gap/level is a cheap and relatively easy thing to do; it’s a good starting point and may well yield positive results. If doing this doesn’t make a difference, you won’t have lost much and can then turn your attention to the more expensive bits (springs etc), knowing you’ve ruled out the simple/cheap things first.

Of course, I’m sitting here hundreds of miles away never having ridden you bike, so to a certain extent the above is educated guesswork, but nevertheless it’s probably worth a try…

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