Three Little Bikers

Three young sheep leap onto their bikes for a day in the country in this winning and energetic picture book. Spiffy in tweed pantaloons and color-coordinated backpacks, they are soon caught up in the promise of adventure. Their progress is temporarily impeded by a gully, then a puddle and, finally, a near-vertical hill, but they call upon team spirit and boundless enthusiasm: ``Should they? Could they? Would they cross? / ``Yes! Yes! Yes!'' Johnston's ( Amber on the Mountain ; Yonder ) text flutters along playfully, buoyed by sound (``flap, flap, flap''; ``whooosh!'' ``chomp, chomp, chomp''), the simple language augmented by varied sentence structure. Endearing illustrations, dominated by spring green and palest blue, are breezy and carefree; Karas ( Nobody's Mother Is in Second Grade ) lightly conveys the joyful ambiance of the story. And with their spirited camaraderie and blissful expressions, the sheep themselves are cheerful charmers. Ages 3-7. (Aug.)