After the 2010 World Mountain Bike Championships, I posted a summary of the bikes which had won elite world championships and Olympic races 2008-2010. The result: overwhelming superiority of 26-inch hard-tails, with only one exception of the races Christophe Sauser's 2008 world championship on a Specialized Epic dual-suspension. Well, since then "29'ers" have become so popular it's hard to even find high-end 26-inch hard tails in shops in the United States. Even the dual-suspension bikes are switching to "29-inch". There's been a move in Europe towards 27.5-inch "650B" wheels, a size which had previously been associated more with randonneuring, and Ritchey just announced a wheel in that size.
So one would expect given the ubiquity of these wheels and their claimed performance advantage that surely the winner of these most important races in the world, racers in which the riders have access to almost any equipment they want, 29'ers would dominate. I don't follow pro-level mountain biking much, so was curious if this is the case. I'll start with 2011 world championships.
The women's race was Catharine Pendrel of Canada won the women's championship. Here's her bike from Feb 2012 (although I'm not 100% sure it was the same one she rode @ Worlds).
2011 women's world champion Catharine Pendrel's 2012 bike
Sure enough, it's a 26-inch hard tail.
The men's race was won by Jaroslav Kulhavy of the Czech Republic. Here's a photo from Canadian Cyclist, via Cycling News:
Jaroslav Kulhavy in the 2011 World Championships
So this morning was the women's Olympic mountain bike race. The winner, Julie Bresset of France. Here's what she rode:
Julie Bresset dominating 2012 women's olympic cross-country
Another point to 26-inch hard-tails.
So my tally is up to 11 races: 3 olympics and 8 world championships starting in 2008. It's a biased selection in favor of duallies since that was the first year a dually won worlds. Yet despite this 26-inch hard-tails are ahead 9 to 2. Both of the two are Specialized Epic full-suspension bikes, the 2008 men's world championship won on a 26-incher, and the men's 2011 world championship won on a 29-incher. It will be interesting to see what happens in the men's olympic race tomorrow.