Bike counter and VGA resolution

I recently bought the Maix Go, and it is definitely a great product. I want to develop a bike and car counter, I think I’m not the only one ! I started from the 20 class demo and added a centroid tracker. , results are pretty good for cars but more erratic for bikes (which are my prime concern !). I think improving the resolution would help so I was wondering if reducing the model to 2 classes only would allow increase resolution to VGA while keeping a decent framerate (25 fps is needed if cars don’t drive too fast). I’m definitely not an AI specialist so I was wondering if some of you had similar thoughts ? Thanks