I said I will offer proof that wheel diameter doesn't effect energy to accelerate, so now I will provide it. By the way, this is from an old post of mine, as you can imagine this subject has been beaten to death a few thousand times on this forum in the past.

Put some energy into a wheel to make it roll and that energy is converted to translation and rotation.

The equation for translational energy plus rotational energy looks like this:

E = ½mv² + ½Iω²

I'm going to use moment of inertia I = mr², as for a hoop or hollow cylinder, and ω= angular velocity (rad/sec), which is related to translational velocity for a rolling wheel (not slipping) by ω= V/r (1 rotation = 2pi radians and circumference =2pi*r)

Substituting:

E= ½mv² + ½mr²ω²

E= ½mv² + ½mr²( v²/ r²)

Notice the r²'s cancel out in the second term and you are left with

**E=mv²**

So, you can see the energy it takes to get a wheel up to certain translational velocity depends on its mass! (There is no radius in the equation, because for bigger wheels, the r in higher moment of inertia canceled the r in the lower angular velocity).

More mass more energy. Higher velocity, more energy. The size of the wheel doesn't matter!

As for the mass, the article used 90 grams more weight for 29er wheels. considering the mass of bike plus rider, that is only a difference of .2 or .3 percent weight. A water bottle makes more difference, as was pointed out in the comments following the article.

Physics aside, all you have to do is ride a 29er to know that these "slow acceleration" claims are false. Riding a 29er, by the way, is something that turbodog has never done :lol: