On days I don't ride I hit the gym. That is a good easy to keep schedule for me. I usually take 1-2 days a week off because of my current schedule. Sometimes on the weekend I will go for a 20-30 mile ride and hit the gym. I don't think there is a good type of weight lifting to make you better at cycling. If you want a muscly look hit the weights. If you want to be faster on the bike ride the bike.