Have you aligned the fork legs?

 

After they got tweaked, yes. And the last time I had the front wheel off, but not since this issue began.

 

I would think the legs should be in alignment, then..... I'd be looking at the rotors to see if they are still 'true'. If they get hot and cannot move on the buttons, they will warp.

 

That's what i thought before, but it's like a spring is compressed and then slowly releases tension, and at times continues past the point that the wheels are moving fast enough to cause a vibration like that from the rotors spinning.

 

It's almost six months later and the riding season is over: did you ever figure out the problem?

 

Pull the calipers and give them a good cleaning?

 

Way to bring it back, Walking Dead.

 

Haha.

I think so... I'm thinking it was the pads sticking to the rotors at low speed, causing a catch-and-release type thing. No issues braking at high speed, and forks have smooth travel all the way through. Pads aren't worn, either.

The only thing I can really come up with is some transfer of pad material on to the rotors due to holding the (front) brakes down while stopped after pushing the front brakes.

The problem seemed to have gone away since I stopped holding the front brakes down at a stop after hard riding, so, I'm not disinclined to believe that was the cause.

 

I was hoping for something more decisive. I had been chasing a vibration issue that was happening on my track bike since new: it would only occur when braking from 5th gear + speeds at the single longest straight at the track, any track. I tried swapping pads, forks, rotors, tires, steering head bearings. I also upgraded the braking system with a Brembo 19x20 mc, and racing quality lines. None of this helped over two years of track use, and since it only occurred at one corner of the track I just learned to tolerate it. Then one day it just went away! I had always made a point of only changing one variable at a time so I would know exactly what "fixed" it - but I didn't take into account tires and wish I would have verified tire balance myself after having new tires installed. This last time just prior to the problem going away I had new tires installed front and rear, and made a point of personally verifying the balance. My problem is that if it had been a tire balance issue, then all the front tires I've had installed since buying the bike would have had to been balanced incorrectly, and that just seems too hard to believe. So, I'm kind of in the same place as you - my problem has gone away - but I am not certain what the source of the problem was. I guess I should just be happy that it went away!