i would think that any bike box would work, youll probably need to take off the tires or at least deflate them to make it fit, since a 29er rim has the same ISO as a 700c rim without the tire that would make me think that any bike box would work, also you could transport your bike in a hockey bag, i hear that works really well and is cheaper than buying a bike box unless you can get a free cardboard one from a LBS.