Here is a tricky situation last weekend, I was the ref. It is the only call in the video I am not sure about. Orange player (Dani) gets potentially toppled by black player (Morgan). There was no call and I had a direct and clear view of the situation.
The situation as seen in the video is the following: Pass comes from the left to the top of the crease. Dani wants to shoot. Morgan rushes out and deflects the ball and starts turning towards the ball, which stays in his vicinity. Morgan per definition is now the ball carrier. This happens before any bike contact is made.
Dani keeps riding in a straight line and gets into contact with Morgan. Morgan potentially gives a little impact to Dani, who ultimately dabs. However, Dani does not seem to slow down in the whole process and potentially also carries momentum into ball carrier Morgan with his foot/pedal, while Morgan is able to keep his balance. It actually seems as if what really brings Dani out of balance is the final contact he makes with the pedal on Morgan’s front wheel, which is at rest.
As said, I did not see clearly that either of the two players was at fault, also given to very short time for either of them to react. It is even not clear to me re-watching it, so I would still tend towards not calling anything.
Here is the video, I recommend watching at 0,25x speed and pause it a lot!