Sigma BC12.12 STS Wireless Computer. Does your current cycling computer tell you how much gas you saved If you're not riding the Sigma BC 12.12 STS Wireless cycling computer, then the answer is no. THE BC 12.12 is a fully functional cycling computer with wireless communication between the sensor and head unit. In addition to all the good stuff like speed and distance, it also gives you the fuel economy of your trip. So, it basically calculates how many gallons of gas your ride saved you. It's like watching money fill your bank account.