My mom is an avid Rails to Trails cyclist. She asked me to help her select a new bike. Mom ranges between 20 - 40 miles on the trails each time she cycles. She is 72 and looks very young and fit, but has medical problems such as two partial knee replacements, RA and neuropathy. Here is her criteria for a suitable bike 1. Hybrid 2. Light, Light! 3. Easy to get on and off. Please help.