Motorcycling is a GREAT activity--for SOBER alcoholics. I know several guys (and a few women) who got into it in a major way post-getting-sober. Their bikes are parked, several nights a week, outside the AA meetings.
But as MOTIVATION to quit drinking? Or, even more unlikely, "cut down"?
LOL, take a read sometime about Bill and Lois's motorcycle "adventures" before Bill got sober. That didn't work out so well in the "motivation to quit drinking" department...