I re-fitted my rack and AGU rack top bag to my Swift today and swung the Twofish bottle cage round to the rear of the seatpost. It fits in the gap very well and the frame "lugs" that take the top Q/R provide an anti-twist platform to stop the cage moving. I may use a strong elastic band or spare Velcro strap to hold the bottle in the cage and prevent it from bouncing out on the UK's pot holed roads. I like the open frame of the Swift and moving the bottle cage behind the seat gives an uncluttered appearance. The rack top bag shelters the bottle from road grime thrown up by the rear wheel.