From Yosemite Ave to Madera Ave and back, the Arroyo path is about 18 miles round trip. There are a few good sized hills, but the path is mostly flat. There is very little shade, so I do not recommend doing the whole thing on a hot day. The bike path is great for all fitness levels. Perfect for walking, running, biking, skating, whatever! Especially great for walking/running with a stroller.