We argue about things like this all day long... there are just so many variables involved in testing wheel sizes... so here we (or they) go...

From Soho Bikes:

"We gathered a “who’s who" of UK downhill and enduro talent (and Rob), headed out of London and hit the trails at BikePark Wales to test the following:

Is a downhill bike faster than a modern enduro bike on a UK downhill track? Which wheel size is faster down a UK downhill track; mid travel 29er, 27.5 or 27.5+?

We taped off the most technical downhill track at BikePark Wales and used Action Sport Timing’s race-timing system to gather data from the riders on their different bikes over multiple runs. The timing data showed which bikes were fastest…but the rider discussion and feedback showed that drawing definite conclusions isn’t actually that simple.

With the likes of Steve Peat, Tracy Moseley, Tahnee Seagrave, Chris Porter and Loosedog Lewis taking part, expect some insightful results, provocative opinions and plenty of laughs in the most exciting episode of Soho Bikes TV yet!"