The shop is close to the 7 million pound country house that Williams has apparently purchased. Fans rushed to see the star in the shop, where the singer splashed out more than 10,000 pounds on two Italian Bianchi bikes.
Shop manager Freddie Platt said: "He just turned up out of the blue." One of the fans, singer-songwriter Emma Payn, 28, of Swindon, said: "I invited him to my gig this coming Saturday and he said he might head along. It's unlikely he will but, hey, we'll see."