Ok this has always puzzled me.....
On my bike, the rear wheel makes a
massive spark - and when you connect the wheel plug power connector instead you can clearly see the spark flying out the sides!!
But on the front wheel, there little to no spark.... Just a very quiet 'click' noise.
Fair enough. But it seriously makes me wonder because the front wheel is more powerful than the rear!!! I cannot explain it. Unless there is a problem with the rear one to cause such a spark, both operate individually exactly the same as driven together so I have no idea why one sparks so much more than the other.