I had an annoying knock from the steering head bearings under braking, so I tightened them up as per "Haynes" and it seems to have disappeared. However, since then at low speed / traffic, it wants to oversteer badly on cornering, but seems fine at high speed?
Any ideas whats causing this?

If your suspension was set-up correctly before tightening the head-bearings then that'll make no difference. Are you sure you've not overtightened the bearings?

If I have overtightened the bearings, is it correctable by loosening or is it a case of permanent damage and need for replacement?

Try slacking it off a lottle and see how it goes.

Coule it be that your knock was not the headstock but maybe wheel bearings/mudguard mounts etc?

You might have just nipped it too tight and now you are putting more force in to move it and getting the reaction from the bike at slower speeds?

Mine is ever so slightly loose and doesn't knock as much as click when in uber hard braking mode. I like the free and easy steering though and so keep it as it is.

I did a TD at cadwell ages ago (2006 gb one I think) and I lent my bike to cgsuperbikes....he was amazed I could ride it as it was clunking and knocking in his hands as he was a racer and gave it the beans..

ANyways...rambling now..remember that needle and balls have different torque settings too...

Just a thought, how much tread is on front tyre?

Gazzahh,

Front tyre only has ~1000 miles on it.

Sounds ok, only a worn front tyre can upset the steering, a sort of falling into the corner sensation.