You'll need adequate space between the BB shell and the chainstay bridge for a conventional center-mount and for the double-legged. I use both of those and the rear mount on different bikes. I've used a center-mount on tour with rear panniers and a handlebar bag. Last tour I began with the rear mount but with four panniers there was too much weight oddly distributed for the rear-mount so I switched to the double-legged center-mount. That still needed a bungee to help keep the front wheel centered when parked.



Random 'net 520 photo shows what looks like adequate space for the double but a current owner can probably chime in with confirmation.