Originally Posted by
Cross Creek
According to Jan Heine, if you don't brake hard enough to lock up the rear wheel (using only the rear brake) your weight doesn't shift forward.
I think that's a mis-quote, or misunderstanding ot the text. Here's the closest match out of your link:
If you can apply the rear brake without locking up the rear wheel, then your weight isn’t shifting forward – a clear sign that you aren’t braking as hard as you should!
Isn't and doesn't are not the same.
Forward weight shift isn't a on/off thing. It'll happen no matter how the bike is braked. It'll happen no matter how softly the bike is braked.
Only that at casual braking, the amount of forward shift is so small that we just write off the forces involved as part of the normal dynamics of riding. They're still there though. Restrain the bike and inertia will continue to push the rider forward
There's no choice in the matter. As long as Rider CoG is higher than the point where the braking force is being applied, the bike will try to rotate forward, or the rider will come off the bike.