I got one from a mountain bike shop that I just put a shim in to use on a yamaha fork and it works ok. The piaggio/gilera forks are thicker at the tube and run higher above the fork, I think so maybe with those you don't need one? But from a bike shop you can ask for a stearing tube extender, riser or adaptor. They come in the 2 standard mountain bike sizes so get the closest. Maybe there's other custom scooter products but I don't know about them.