You guys are all riding road bikes, or are any of you on mountain bikes? At age 63, I think I've put in a big day when I ride 40+ miles on my Xizang mountain bike. Big tires give me a serious workout. But unless the weather is horrible, I ride some every day. New girlfriend is taking up lots of my spare time right now, though. So last week I talked her into buying her own bike and coming along. I need to be patient as she builds strength and skill.