I’ve rode 24″, 26″, 650b, 29″ and 29″ front with 26″ rear – all good fun in their own way as they all ride and handle different over similar terrain, none were necessarily quantifiably better or worse than the other for the entirety of a given trail, they’re just bikes and if you’re a crap rider on one wheel size you’ll be an equally crap rider on any other wheel size so stop believing there is a holy grail of wheel size that’ll turn you into a riding god.

If you’re tall n’ lanky like a big streak of piss then a 29″ wheeled bike may be the better bike for you, if your short n’ squat like a turd dropped from a height then a 26″ wheeled bike may be better for you, if you’re one of those “normal” folk in the middle then perhaps a 650b wheeled bike may be better for you.

Personally i resemble a short n’ squat turd so i ride a 26″.

If you’re comparing, would you use the same travel forks, or the same length/height?

No maths required. The rolling resistance thing is a bit of a red herring as it is more related to tyre pressure. Simply put it is all about conservation of momentum. A larger wheel effectively flattens a bump, meaning less kinetic energy is wasted when the wheel rolls over a bump (i.e. less speed is lost), which in turn requires less energy the rider has to put in to maintain speed or in riding over bumps on a downhill. This is obviouly only of importance to those where speed over the ground is important – if you are into jumps, then suspension is far more important so you’re not going to be keen to compromise suspension travel for speed over the ground – so 26ers will still rule here. The reality is can you tell the difference? I have, but it is not that great – its not transformed me from an average rider into a superstar overnight. I wonder if they have these debates over on the tractor forum?