In this discussion between Malcolm Gladwell and Nicholas Thompson about the World Track and Field Championships, Gladwell brought up a concept called the Kipsang Number.

I watched the marathon and was struck (as I always am watching marathons) by the same dumb, obvious point: they are fast. It’s worth dwelling on this a moment. Back when Wilson Kipsang set the world record (which was then promptly broken), my running friends and I came up with the “Kipsang number,” which represented how long could you keep up with Wilson Kipsang while he was running twenty-six miles. I am a devoted runner and my Kipsang number is less than a mile. If I’m lucky, fourteen-hundred metres. You are a really good runner, and I’m guessing your Kipsang number is two miles. The average, healthy, athletic, American, twenty-two-year old varsity athlete in a sport other than track probably has a Kipsang number of between 400 and 800 metres. To recap: you could keep up with him for a quarter of a mile, then you would collapse in exhaustion. He would keep running at the same pace for another twenty-six miles.

My cycling friends and I often ponder a similar number when out on group rides: on a flat road, how long can you bike at the speed that professional cyclists ride at in the flats in the peloton? Or how long can you hold the average speed of a professional climbing expert like Nairo Quintana on a cycling climb?

This would be a fun charity event, either on the track or in cycling, to invite average Joes to try to keep up with Kipsang or a strong pro cyclist like Fabio Aru for as long as possible, and soon as you fell behind, you'd be eliminated. Since that is logistically too complex to set up for all but a few people, perhaps fitness apps like Strava can add in virtual challenges like this.