I bought this rack about five years ago. It is pretty sturdy overall and gets the job done, but I find it to be more of a hassle than it's worth. The front rear must be removed and the mount has to be adjusted for each individual bike fork, meaning that if you use many different bikes, it has to be adjusted every time. It is not compatible with thru-axle forks.
I prefer the Yakima Kind Cobra rack over the Viper.