I just had a class 3 hitch installed on my car and I’m interested in what lock others use for a their rack. The Kuat Transfer rack I’m getting does not include a lock - it’s an add on cost, but I’m thinking of something more robust than the one Kuat sells. I’m planning on a good chain to secure bikes when the car is not being driven and a hitch lock for the bike rack. There are certainly lots of options on Amazon or other sites.
I have the Thule rack and use the locking pin that came with it. Mainly because it is threaded. Since I have a Jeep and use and extender, I use a locking no rattle pin on that attachment point.
About a week ago I had a class 1 hitch installed and picked up a Thule Vertex 4 bike rack. It attaches to the receiver with a threaded pin.
I looked around for cheaper ones, and in the end I ordered the $70 Thule one. There are options out there (threaded bolt with lock washer, etc.) but I just went with the simplest solution even if I spent and extra $40. I was surprised there weren’t more aftermarket options out there, and even then the ones I could find were out of stock.
I personally wouldn’t buy a rack that didn’t include very solid locks for the rack and the bikes. I have the Thule T2 pro XT and the locks are great.