If you are serious about your training, you may want to invest in a sport watch. It comes with a weight of 81 g. Use the built-in heart rate monitor to keep track of your training
From Amazon
SUUNTO 9 Baro: Rugged GPS Running Cycling Adventure Watch with Route Navigation
365rider
Suunto 9 Baro Watch Black
This product is also available at 1 unverified merchant.