The Time Bike is the sixth book in Langton's loosely-connected Concord series for children. Although it does contain references to the prior novels, it can stand alone. Unfortunately, it can't stand too well, with or without its predecessors - The Time Bike is a disappointing entry in a series that contains wonderful books like The Astonishing Stereoscope and The Fledgling.
Edward's new bike is stolen, but he recieves another one from Prince Krishna, the deus ex machina of this series. To Eddy's dismay, the replacement bike is old-fashioned. At first he's embarrassed to be seen with it, but he feels better about it after he discovers it can travel through time. He and his associates have a few disjointed temporal adventures and defeat the nefarious Prawn and Preek.
The Time Bike lacks both the intelligence and the magic that made the first four books in this series so marvelous. The other books, too, benefitted from a sense of unforced depth and penetrating insights, while this book skims along the surface and very deliberately does not look too long or too hard at anything.
Over all, a rather depressing book, with flaws I hope will be corrected in future entries in the series. Jane Langton's children's fiction is well worth reading - but please, start with The Diamond in the Window. Starting with The Time Bike is a disservice both to the series and to the author.