I have an older Yakima roof top bike rack with the clamps that grab the down tube. It's designed for smaller diameter tubes and doesn't work with odd or larger type tubes. I'm going to be hauling two bikes both of which have over-sized tubes so I need to get two new bike mounts.

What I'd like to know is if I should get another set with larger down tube clamps or a set with fork mounts.

One of the bikes is aluminum and the other is CF if that makes any difference.

Also would like to get a couple of the covers/bras for the bikes and am looking for recommendations for these too. I've only seen ones that work with fork mount racks. Do they have them for the down tube mount racks?

Thanks