I am in the process of making a rear pannier support for the rear carrier. I wanted to use my existing Arkel RT40 and RT60 panniers, and still be able to use my Arkel Tailrider rear bag. I also wanted the panniers to be able to be easily removeable.

After trialling different pannier positions, I decided to mount them relatively high up. This achieved two things - it moved them forwards over the position they'd need to be if mounted low, and it also means that they will not rub on the moving mudguard stays (when a rear mudguard is fitted).

Before starting work on the final adaptor I did some testing with realistic loads in the panniers and found the balance and handling fine. I say that because I think many people's reaction will be that the bike will be unbalanced and hard to ride. It isn't - and in fact changing the weight in the front bag makes more of a difference to bike handling. That said, put too much weight in the rears and the seatpost mounting bolt (or anyway the palstic bushes) start to flex and the rear assembly can oscillate sideways. (The main mounting point for the carrier is the seatpost bolt.)



This pic shows the rear adaptor in place with two RT60 panniers, foam sleeping roll and tent. The Tailrider bag sits between the two panniers. The front bag is a Brompton (adaptor described earlier in the thread).



Rear view. I don't have in place the long tent and sleeping roll tubes that attach at the back of the RT60s, but there's plenty of room for them when I do attach them.



The adaptor. It sits over the rear tube of the rack. The panniers hang on the cross-arms and the lower hook fittings of the panniers go into the open vertical tubes. The link at the top stiffens the structure and also gives me a tie-on point for the tent and foam bed roll.



I looked at using a quick release clamp and/or wing nuts to hold the adptor on and then decided that simple cable ties would be lightest and easiest. A half-round tube brazed to the cross-bar locates the adaptor on the carrier.



The adaptor weighs 500g and will easily pack into a suitcase with the broken-down Birdy. Now I just need to finish brazing it, do some sanding and then give it some paint.

Final point - the new rear suspension bush (also described earlier in the thread) works well with the bigger load - for example, it doesn't bottom-out.