The last couple of seasons I have replaced cycling over the winter with running 3 days a week and weight lifting 3 days a week. With everyone else riding zwift all winter, I can't keep up with the fast group on the early spring rides, but I think it's better for my overall health, and I'm back it top form by June. I can't think of anyone who rides GR's who just completely takes the whole winter off, but I do know a few people who never do anything longer than a 200k who use the opener as motivation to get back in shape after taking the winter off.