The term 29er was originally a reference to the diameter on the wheel/tire combination which the initial mtb tires available for 700c rims put in the neighborhood of 28.5 inches.
Which isn`t even close to my road bike, which has a diameter of 26.5 inches with 700 x 23 tires.
Of course commuter tires like the 700 x 33c on my hybrid have a diameter of 27.5 inches.
Neither of those frames has the clearance to a 700 x 60c sized tire.
But I did build up several 29ers last year, as well as a number of 26in mountain bikes. So after having to colaborate on the frame specs and deal with clearance issues - I kinda thought posting the key points might be helpful.
Another suggestion might be to double-check with an encyclopedia to sort out opinions. Lots of people think they`re driving sports cars when the only thing `sporty` about it is the styling.
Regarding the photos attached: One is a 26in frame and wheelset, the other is a 29er wheelset (700 rims on mtb bubs and axles). The 29er wheelset WILL fit in the 26in frame - but theres only clearance for 40mm tires - maybe.
None of these will fit in any bike that doesn"t have exactly the same axle width.