I had the use of a Tailwind one summer. After getting used to it (trying to clip in on an incline, climbing in super low gears because of less leverage spinning my legs like a hummingbird but going about 3mph, etc.) I gave it up. Made me nervous with my head no higher than a truck's tire, couldn't get up off the saddle and so on. Were I injured or disabled, I'd take one up in a minute to avoid quitting cycling. Otherwise, back to my DF.