My winter project couple winters ago. I fabricated these to sit right in the rails. 1 for each bike tire. Then bikes sit right up. I haul 4 bikes. Velcro strap around each tire to secure it to rack and from jumping.
2 middle bikes get Velcro strap to the upright bars. The outside bikes get rubber snubber to the middle bike. Finally I take a strap from the back frame up and over bikes and back down to rack as extra secure.
Keeps from having to ratchet strap the bikes to hard. I bent two rims doing that first year.
Overall I give them a B for idea of rack but a D for execution. Love not have to remove tires.
Oh then a bike cover to cover bikes during rain.