Clockwork Orange, may I ask if you were on the prednisolone just for asthma, or was it for an arthritis condition as well?
I can only speak from my experience of course, so none of this may be relevant to you!
I have inflammatory polyarthropy (a fancy way for saying I have inflamed joints but it's not rheumatoid arthritis). I've been on prednisolone for seven years now. Started on 7.5mg per day, then on 5mg for about four years. Whenever I flare I increase the dosage for a few weeks. I'm currently coming off taking 10mg a day for a week.
I keep trying to lower my dosage as the side effects of that much prednisolone for so long are vile. I've managed to get down to 1mg a day and then my joints decided to flare up again.
But as I also have asthma, the prednisolone completely masks it at 5mg. As soon as I start dropping the dosage, I have to go onto a preventer again (Seretide). But as I'm sure you know, preventers take some weeks to be fully effective.
How long is it before your ride? Maybe you could talk to your GP about taking a hit of prednisolone for a few weeks to get you past the ride, then taper off. Or if it's a while away, try a preventer.
I think being active is the important thing, and although I don't like taking 6 different tablets morning and night, if I didn't, I wouldn't be able to move.
Good luck!
Edit: BTW, I hope I didn't sound too unfeeling! It's just that I've learnt over the years to be a bit dismissive of pain as I don't like sympathy. Believe me, I do feel for you. I hate it when it's a choice between the unpalatable and the unpleasant!