Just starting to investigate things...the left floating part of the brake rotor is very loose, literally making a knocking noise as the wheel spins. It has a lot of lateral movement of about 1mm (maybe a bit more).

This is obviously too loose. Ive got another pair of rotors and the only bit that moves is the round bit that turns. Can these be tightened up? Why has it become so baggy? Could this be the cause of the pulsing? 

Just to add -  the pad wear seems even but I haven't checked the calipers properly as yet. Eyeing down the spinning rotors (not using any measuring tool) they don't look significantly warped or discoloured either.

Here is a video...

https://youtube.com/shorts/m-C8mq_CDnA?feature=share" rel="nofollow - https://youtube.com/shorts/m-C8mq_CDnA?feature=share

They do wear naturally and cannot be tightened only replaced. 

I’m not sure what the acceptable movement is on the disc bobbins for an mot, but I’ve some virtually new fully floating discs with anti rattle bobbin dampers that can’t be far off yours. However, they are fully floating discs and not semi floating discs. You have forward and backward movement to account for as well as side to side. 

Grab a new set of Brembo off Griff at AP and see another 20 years. 

The sunstar discs Aprilia put on the later Gen2’s had a fair amount of movement from new. 

Might be worth swapping just to prove if your on the right track. 

I will report back. 

Twenty miles of dual carriageway with them rattling like the tambourine in a primary-school orchestra, and they'd knocked the pistons back into the caliper. Luckily there was nothing coming on the roundabout.

The discs on my  Mille don't move....but I can't see what the point of floating discs was in the first place. Surely you want the wheel hub to act as a heat sink, not insulate the disc from the wheel and let it flail about?

If the rotor itself is warped then letting it float from side to side won't help. And there's a load of components in there to fail and kill you.

Am I missing something, or is it just 'blingineering'?

The bike is still bouncing under braking – it's only noticeable from 15mph down to a stop with very light braking. Starting to think suspension. I'll give it a couple of clicks on the rebound and see if that works. I didn't change the pads, but can't see why that would be it.

disconnect that to see if it cures the issue 

First ride for a week - it’s much worse now!!

I would now say yes, it has progressed to a judder. Noticeable at all speeds under all breaking conditions (lightly or harder braking). 

Applying the brakes at around 70mph it’s like a jack hammer. Slowing with speed. 

Head stock check then. 

I remember cleaning one side very well. But now you mention it, I didn’t spend too much time on the other side. If all else fails I’ll go back. 

Well I’ve just checked the head bearings and they didn’t seem loose at all. But still gave it a 1/16 of a turn. Test ride- no difference. Suns going down and can see the headlight bouncing as I come to a walking pace. Maybe now a little weaving so I’ll back that off again. 😡

Backed off the steering damper all the way and no difference. 

New pads next. 

Check front wheel is correctly fitted

I think it’s the pads. I’ll have a proper ride tomorrow to confirm but it felt good. They need to bed themselves in a bit obviously. 

This is where I hang my head in shame. 😔 When I cleaned the calipers I didn’t check the brand of pads. I just looked at the wear and thickness. They were running low but me being a tight arse I thought I could get a few hundred miles out of them. 

Turns out they are brembo pads and could well be, most likely, the originals. NINETEEN YEARS OLD!!

I’ve fitted some ebc ones. 

  I’ll let you know tomorrow. Sorry, I feel bad for wasting your time thinking of solutions. Well I hope I’m right. And if I am well thanks for the thoughts, at least I’ve given the front end a good check over. 

🤪

hopefully you have it sorted