I bought two of these Thule racks. When I got them home I found that neither my Trek or my Spark mountain bikes, both with use a standard size mountain bike tire, will fit in these racks. The straps are too short to go around the rim and tire! So, I contacted Thule, after all, these are expensive racks. Here is their response, and I quote:
Thank you for contacting Thule Customer Service. The only suggestion we can recommend is to let air out of the tires. Unfortunately Thule does not offer longer replacement straps for the Big Mouth.
So, basically, what Thule said is, "You are on your own, our rack doesn't work with mountain bikes, so you will have to LET THE AIR OUT OF YOUR TIRES EVERYTIME YOU TRY TO USE OUR RACK!
Terrible product, terrible company. These don't work with mountain bikes, so stay away from them.
2009 Prius Prius