My Honda CBR1000RR Fireblade has developed a front-end patter during braking. I've checking the head races, bled the brakes, checked the preload and damping are set to recommended values, and made sure the front wheel is tightly in place. There's no patter at speed so I've discounted an out of balance front wheel. How can I cure this, it drive me mad....

It sounds like your discs might be warped. The rotor's service limit is only 0.3mm so you might not spot this distortion by eyeballing it. Instead you need to clamp dial gauge to each leg in tun, raise the wheel, and spin it to check the run-out accurately not easy on a drilling disc.

Check the fork oil as well because previous owner may have used too much, or too heavy a grade. This could stop the forks following the road surface accurately, especially when they're loaded up on the brakes. So instead of soaking up the bumps, they'd allow the tyre to skip off the surface and lock up momentarily which you'd feel as patter.

Similar thing happened to me, not a Fireblade. I noticed it first on a trip to Khao Yai. It turned out to be the wheel bearings. They are cheap and easy to get replaced. Depending on where you are:-)