I too have Crohns arthritis. Haven't had a joint pain episode recently, so I don't know how biking will affect it. My last serious flareups what I would do was put on long woolies under a windproof layer, then walk (straight forward) for miles until I'd walked myself warm enough to be able to turn, at which point I could walk home. Warming up the muscles did the job, but walking was pretty painful at the start. Next flareup I'm thinking the bike might work better. I warm up faster, and I don't have to swivel at the hips to turn. But I am testing bikes carefully before I buy. I need the bike to fit well so my back, neck, shoulders, knees are as comfortable as can be.