The Pinhoe Egg by Diana Wynne Jones

out of breath to do anything but nod. So Cat took the lead and swungSyracuse into a nice broad road leading away left. SHALLOWHELM, the signpost said. UPHELM .
    About half a mile later, when he could speak, Roger said, “This road can’t be right. It should take us back to the Castle.”
    Cat could still see the wood, still in the same place, so he kept on. The road bent about, among nothing but empty countryside for what seemed miles, up and down, until Roger was more the color of a peony than anything else. Then it swung round a corner and went up a truly enormous hill.
    Roger let out a wail at the sight of it. “I can’t ! I’ll have to get off and push.”
    â€œNo, don’t,” Cat said. “Let me give you a tow.”
    He used the same spell he had used to keep Julia from falling off Syracuse and flung it round Roger’s bicycle. They went on, fast at first, because Syracuse still regarded every hill as a challenge to gallop, then slower—even when Cat allowed Syracuse to try to gallop—and then slower still. Halfway up, when Syracuse’s front hooves were digging and digging and his back ones were scrambling, it dawned on Syracuse what was going on. He looked across at Rogerand the bicycle, so uncannily keeping beside him. Then he threw Cat in the ditch and scrambled through the hedge into the stubble field beyond.
    Roger only just saved himself and the bicycle from falling in the ditch too. “That horse,” he said, kneeling in the grass beside his spinning front wheel, “is too clever by half. Are you all right?”
    â€œI think so,” Cat said, but he stayed sitting in the squashy weeds at the bottom of the ditch. It was not so much the fall. It was that Syracuse had broken the spell quite violently. This had never happened to Cat before. He discovered that it hurt. “In a moment,” he added.
    Roger looked anxiously from Cat’s white face to Syracuse pounding happily about in the field above them. “I wish I was old enough to drive a car,” he said. “Or I wish that there was some way of moving this bike without having to pedal.”
    â€œCouldn’t you invent a way?” Cat asked, to take his mind off hurting.
    They were both sitting thinking about this, when a boy on a bicycle came past them up the hill. He was riding an ordinary bike, but he was humming smoothly upward at a good speed, andhe was not pedaling at all. Roger and Cat stared after him with their mouths open. Cat was so amazed that it took him several seconds to recognize Joe Pinhoe. Roger was simply amazed. They both began shouting at once.
    â€œHey, Joe!” Cat shouted.
    â€œHey, you!” Roger shouted.
    And they both yelled in chorus, “Can you stop a moment? Please!”
    For a moment, it looked as if Joe was not going to stop. He had hummed his way about twenty yards uphill before he seemed to change his mind. He shrugged a bit. Then his hand went down to a box on his crossbar, where he appeared to move a switch of some kind, after which he turned in a smooth curve and came coasting back down the hill to them.
    â€œWhat’s the matter?” he asked, propping himself on the bank with one boot. “Want me to help catch the horse?” He nodded at Syracuse, who was now watching them across the hedge with great interest.
    â€œNo, no!” Cat and Roger said at once. “It’s not the horse,” Cat added.
    Roger said, “We wanted to know how youmake your bike go uphill without pedaling like that. It’s brilliant !”
    Joe was clearly very gratified. He grinned. But, being Joe, he also hung his head and looked sulky. “I only use it on hills,” he said guardedly.
    â€œThat’s what’s so brilliant,” Roger said. “How do you do it?”
    Joe hesitated.
    Roger could see Joe was very proud of his device, whatever it was, and was itching to show it off, really. He asked coaxingly,