Cyclist BikeList by Laura Robinson
Cyclist Bikelist has great illustrations with useful accompanying text. This book is geared to children in middle school and older but may be accessible for those in upper elementary. Robinson's book is a nice survey of cycling and repairs but sadly lacks any real depth. Despite that it could be the right amount of fuel to ignite a child's interest to learn more on the topic.
You can find similar cyling books for children in the Minuteman Library Network catalog. Here's a few others to sink your teeth into: