Wheel Size - Mountain Bike Zen
What size mountain bike wheels should I go for?
Generally mountain bikes come with 26 inch wheels, for that reason, if you are a grown adult, you are most likely to end up with this sized wheel and there is no reason not too but there are other choices as detailed below:
24 inch wheels - these can be handy for smaller people and children as it reduces the frame bar height from the ground, reducing the inside leg required to fit on a bike comfortably. You should not however simply plonk some 24 inch wheels on a bike that was intended for 26 inch wheels as many aspects of the overall bike build will be affected including aspects which will may reduce the safe handling of the bike such as pedal clearance from the ground, the positioning of brakes etc. 24 inch wheels are also used on stunt bikes and jump bikes as they allow for more concise manoeuvring. Some street stunt bikes and bmx bikes will use smaller wheels but these are not mountain bikes.
29 inch wheels are available, although not very common as the overall wheel strength and stability is reduced due to the extra distance the spokes need to cover from the rim to the hub, they also adversely affect steering but have been touted as the new standard for downhill racing. Unless you are already an experienced mountain bike rider and you are into downhill racing, preferably in a straight line, then you should not really be considering a 29 inch wheel. That said if you are extremely tall then this may be a better choice for you in the long term and to avoid hitting your chin with your knees on a midget 26 inch bike! You should not try and put 29 inch wheels on your 26 inch wheeled mountain bike, if you can get the wheels to go round at all it will be dangerous!!!