Walker drew the outside lane for the semifinal, but nailed her gate in a move reminiscent of her effort in the London Olympics, pushing through to second behind Crain.
She just missed the same snap out of the gate from lane eight in the final and was pushed on to the concrete edging on the outside of turn one.
"I just had to brush off some speed to manoeuvre around the concrete section and once you slow down even momentarily in a field of that quality then you will struggle."
She fought from last back to sixth to complete an excellent overall performance.
"My two big markers were the podium at the time trial at the worlds and now this performance here.
"I was the second fastest rider today behind Mariana Pajon and I was able to mix it well in the racing," said Walker.
"I have the speed and the fitness. I just have to work on improving the gate and I think I can get on to the podium."