There's a world class sporting event for both Saturday and Sunday this weekend. Both are part of the London Prepares, Olympic 2012 test events series and both are free to spectate.
On Saturday it's Marathon Swimming in the Serpentine, Hyde Park. The London 10km Marathon Swimming International is an invitational event, featuring the top 60 ranked swimmers in the world covering 10km over 6 laps of the Serpentine Lake. The women's race starts at 10am and the men's at 2pm.
On Sunday, the London-Surrey Cycle Classic takes to the roads to test out the Olympic road cycling route. In 2012, the men race over 250km but all 148 riders tackle 140km this Sunday, setting off from the Mall at 9am. Line the Mall for the start and finish or find a spot along the route in West London.
Check for TFL advice on road closures in Westminster, Chelsea, Fulham, Putney, Richmond, Hampton Court, Kingston upon Thames and parts of Surrey, from early in the morning until mid-afternoon.