The Time Bike (Harper Collins, 2000, middle grade, 176 pages) is the fifth book in Jane Langton's series about the Hall family of Concord, Massachusetts. The first is The Diamond in the Window, published way back in 1962, the eighth, and most recent, is The Dragon in the Tree, published in 2008.
The Hall family, brother and sister Eddy and Eleanor and a scatter of relations, are the sort of people to whom magical things happen. In the case of this book, the magical thing is a bicycle that arrives from India one day. A very old-fashioned, out-of-date bicycle, that no self-respecting boy would want to ride. But when hiding the bike out of sight in a nook next to the coat closet, Eddy notices that it is, in fact, rather extraordinary.
"It trembled slightly under his hands as he propped it upright, almost as if it were alive. Little sparkles flickered around the rims of the wheels. And there was a sound, a kind of whispering murmur." (page 29). But most extraordinary of all are the two dials, one labeled Days, the other Years. And then, just to make things completely clear, Eddy notices the label saying "TIME BIKE."
It is, indeed, a bicycle that allows its user to travel through time....and Eddy, and his sister Eleanor, use and misuse its magic in the traditional way of these things, very Edward Eager-esque. But despite misadventures and lost opportunities, it is thanks to the bicycle that the children are able to save their beloved family house.
Story-wise, it's lots of fun in an old fashioned feeling, summer-adventurish way. Timeslip-wise, it's disappointing, because the time the two kids spend in the past doesn't really seem of great interest to the author. She doesn't linger in it--it gives more a whisking feeling than a true immersion (if that makes any sense)--only 6 pages out of the first 95 are set in the past, and nothing much happens.
And the result is that the present, with the charming eccentricities of Aunt Alex and Uncle Freddy (obsessive devotees of Theroux) is much more engrossing. In a nutshell, this isn't one to read for Time Travelness, but rather for charming every-dayness spiced with magical fun.
It's not necessary to have read any other books in the series before reading this one, but it's not the most emotionally resonant or powerful of the series, and so isn't the best place to start, because you might not want to keep going. And there's also no good reason why you wouldn't want to treat yourself, if this sounds the sort of book you like, to the whole shebang, read chronologically. I myself prefer Eager, for the somewhat snappier dialogue, but there are many passionate devotees of Langton's books, in particular of The Diamond in the Window (I have linked to its Amazon page as proof of this!).