Always carry my bike in the back of my hatchback but its becoming a bit of a faff.

Thinking about a rack and was going to go for a Thule 591 cycle carrier. Anything else I should consider? How much impact do they have on fuel consumption? Also do people use a separate lock to lock bikes to their rack?? Also where's the best place to buy from?

I like the look of the Thule racks that sit on a towbar but they're too expensive for me!

Any suggestions most appreciated 🙂