Hasta La Motion!

I was wondering if anyone could offer me some help.

I am just learning about render passes for a project in which I want to composite a rendered image (of a bike) into a photograph. I have set up some image based lighting and also used an hdr image for reflections.

When I render out the passes for the chrome material something goes wrong when I try to composite them together. The three passes I am using are, diffuse, specular and reflection.

The diffuse pass is pure white, which I think might be causing an issue. I have tried many different methods of merging them, tried multiplying the reflection and the specular together and then adding this to the diffuse. Also tried adding them all together.

For some reason I cant get the reflections to show up correctly, I am missing a pass or doing something wrong?

Many thanks.