Triathlon swim-cycle-run is a very popular sport around the world. As the muscles used for running and swimming are different to those used for cycling, early triathlon bikes were normally uncomfortable. Early pioneers modified their bikes to change their riding position to better utilize the same muscle sets. These days Triathlon bikes have a slightly more forward position than a standard road race bike. Extended "Tri" bars are very popular, allowing an outstretched more aerodynamic position to be attained.