I have a mountain bike with no mount points, and use the snappily-named Axiom Journey Uni Fit Mark 3
It attaches to the rear skewer and seatstays. It looks pretty neat and I think it supports up to 50kg. The price seems to have gone up 25% since I bought mine, though.http://www.halfords.com/cycling/bike-ac ... nnier-rack
The photo on the Halfords site has an ugly silver bit to attach the top of the rack, but this can be replaced with the black rods that are laying by the side of the rack.
The only difficulty I had was in attaching it to the rear skewer. There wasn't much left protruding for the nut to clamp onto. After a while the end of the "shoe" that the skewer goes through started to bend in to the dropout gap, the skewer was bent quite badly!
I spent ages trying to find a solution. I wrote to the manufacturer asking for help as I assumed that lots of people would have the same problem, but they said they weren't aware of any issues or solutions.
Eventually I found one shop (SJS Cycles) that sells 145mm OLN skewers for tandems, which are the perfect length (10mm longer than my standard rear MTB skewer), and I got a 10mm diameter washer to put between the dropout and the shoe to stop it bending in.
I've had it a few years now, and never had any more problems with it. I'm really happy with it (in the end). Here's a pic on my bike:https://www.dropbox.com/s/vtfjn6g7igkjc ... k.jpg?dl=0