Equilateral triathlons only exist in theory. The idea is to create a perfectly balanced race in which all three legs require roughly the same amount of time to complete. The argument for the creation of an equilateral triathlon is that the traditional triathlon format gives unfair advantage to runners and cyclists, while shortchanging strong swimmers.
In traditional triathlons, the running and cycling legs of the race are considerably longer than the swimming leg. In an Olympic triathlon, for example, the distance of the cycling leg makes up 78 percent of the total race and running takes up 19 percent, leaving only 2.9 percent for swimming [source: De Veaux]. In an Ironman triathlon, the discrepancies are even greater, with a running portion that is 48 times the length of the swim.
The proposal, formerly made by Richard D. De Veaux and Howard Wainer in a scholarly paper called "Resizing Triathlons for Fairness," is to make all three legs of the race take approximately two hours. The world record for a marathon is 2:06:50. World-class swimmers maintaining a brisk pace of 1:03.5 per 100 meters could conceivably swim 12,000 meters (about 7.5 miles) in around two hours [source: De Veaux].
Instead of a traditional triathlon with distance proportions (swimming:cycling:running) of 1:11:48, an equilateral race would be 1:3.5:8 [source: De Veaux]. The current Olympic distances are 1.5 kilometers (0.9 miles) for the swim portion, 10 kilometers (3.1 miles) for the run and 40 kilometers (24.9 miles) for the bike ride. The proposed distances for an equilateral Olympic triathlon are 2.7 kilometers (1.7 miles) for the swimming portion, 10 kilometers for the run and 22.4 kilometers (13.9 miles) for the cycling. In this format, the swim is nearly doubled and the cycling portion is almost cut in half.