Okay, first to admit I’m no engineer. But what does everyone make of this video? (The original post has now had almost 70,000 views and continues to draw a wide range of viewpoints.) This is an Elite Men’s CX race. Watch the rear wheel of the 4th rider, white kit on the inside. It seems to start spinning, fast, before he’s even pedalling. Looks somewhat dodgy, but hoping to get some feasible explanations here. Optical illusion?