GLL - Sands Centre Book FREE Entry Tickets Activities Food & Stalls Business Erica Robison & Kayley Rowland wil set you through your paces on a Wattbike to measure your health stats! What is a watt bike? What is a Wattbike? It is THE indoor training bicycle! ... The key difference between the Wattbike and every other indoor bike is that the Wattbike accurately measures power output in Watts. Within seconds we can be accurately measuring your power output, your pedalling technique and heart rate. GLL are the largest UK based Not for profit charitable social enterprise delivering leisure, health and community services. GLL exists to make community services and spaces better for everyone. All surpluses are invested back into providing quality services for the good of the communities where they operate.