This morning I took all the invalid gear back to the rental place; raised frame with toilet seat, raised chair, handy trolley. I don't need any of these any more, though lowering to the toilet does still require some thought, for a few more days.
This afternoon, after a couple of hours on the sofa, I rode my mountain bike to Bottle Lake. It was OK, but the forest has been milled a lot and generally it's not as nice as it was. After 30 mins of quiet riding, with occasional side trips into the twistier tracks, I rode home feeling that it hadn't been that enjoyable, riding in the dark forest or across milled areas with new seedlings planted.
Just out of curiosity I wheeled out my Avanti Blade hybrid commuter, and found that I could straddle the seat quite easily. A quick pump of the tyres (unused since June and down to 30psi) and I was off down the road - what bliss! In a few turns of the pedals I was doing over 20kph and having a great time. So that's my rehab plan from now on; steadily longer bike rides around the local roads.