“My bike’s better than yours.”
“Ain’t.”
“Is.”
“Ain’t.”
“Is.”
“Whoah, let’s ask someone neutral, like the Swiss.”

So that’s what the Swiss national MTB team has gone and done — comprehensively settled the argument about whether or not a 29er is better for cross-country than 26in.

>>> Size matters part 4: The accidental benefits of 29ers

We guess no one told them about 27.5in hey? Never mind.

A special XC course was laid out in the shadow of Mt Toblerone (no, really). Half was designed to favour a 29er, with more straights, downhills, wide turns, roots and stones. The other half was meant to be easier with 26in wheels — more climbs and twisting tightly.

Both halves were planned to take the same time, as measured by a precision timepiece. Then 10 world-class riders did multiple laps over two days.

>>> Complete guide to wheelsizes: 26in, 650b, 650b+, 29in, 29in+

The results

Emulating the exactness of its national railways, every possible piece of data was crunched and digested more thoroughly than a bar of Lindt.

The result was clear — riders’ times were, on average, 7.5 seconds faster round two entire laps on the 29er than 26in. That corresponds to a performance improvement of 2.4 per cent.

Every one of the 10 was fastest on the 29er and each, before being told their times, had also rated the 29er as giving a better ride. All this without having to put any more power into the pedals.

So, even though the XC course was designed to produce the same results for 29ers and 26in bikes, the bigger wheels were faster.

In a typical World Cup race, the advantage would equate to a rider finishing 135 seconds earlier, and 14 positions higher, should they switch to big wheels. “There, told you so.”

>>> Which wheel size is best? (VIDEO)

Citation: Thomas Steiner, Beat Müller, Thomas Maier & Jon Peter Wehrlin (2015): Performance differences when using 26in and 29in bikes