Question about Yakima bike mounts : rcycling

Official Gazette of the United States Patent Office: Patents yakima t slot bolts Shop T Slot Bolts for Thule, Yakima Roof Rack Cross Bars, Platform, Cargo Basket, Stainless Square T Track Bolt Adapter to Secure BikeSkiKayak Rack, yakima t slot I have some T-slot style bolts for the front and it seems like that will be easy But the rear looks tricky since the bolt head goes in the

yakima tslot accessories T bolt and spacer that the Ski rack mount on to I am going to pick one up today I found a forum where a user said he had to grind the bolts