I recently bought a Trek Navigator 1. I just installed a hitch and a Allen 2 bike rack. BUT the Trek has a verry angled top tube. so the front tire is only a couple of inches off the ground. Would a Yakima or other brand tube adapter work on the Trek? Which is stronger or rather snugger fitting? Thanks in advance
Yakima and Thule and probably most other rack companies have top tube adapters. They all recognize the need to accommodate the sloping top tube/y frame/children's bike market. They will all function relatively the same. Unless you have an ultra lightweight delicate carbon frame/seatpost, which I don't believe your bicycle qualifies for that, you should be fine.
Most of them are adjustable so you can make them fit snugly and securely.