In recent years, the industry has been heard talking of shorter stems, increasing reach numbers and front centers getting longer. Antiquated designs that carried geometry over from our road cycling cousins that use long stems to place your body in an efficient pedaling and climbing position are quickly heading out of fashion. Stubby stems and lengthy frames are in. Mondraker and their 'Forward Geometry' have been leading the charge since Fabien Barel put a ten millimeter stem on his huge Summum downhill bike. Since then, some years passed with nothing much to speak of except for savvy riders choosing longer frames then scaling back their stems. Recently, however, bike makers have responded with vanguard brands now offering stem-corrected designs with much longer front-centers.
Why would you shoot for a longer frame and shorter stem? Well, if you're planning on any kind of interesting or technical mountain biking, the shorter stem will quicken up the steering of the bike and place your hands farther behind the front axle. These changes will give you more stability and less chance of flying over the handlebar on steep downhill sections. Of course, the frame size will need to be extended to prevent a sore lower back, and even worse, looking like the infamous French Hunchback when riding. Choosing a larger frame increases the wheelbase and offers yet more stability on the downs. The downsides? If you're racing cross country, or climbing mountains, then you might want to stick to the old fashioned approach. A longer stem will keep your weight over the front on steep climbs and front-wheel wandering will decrease.Opinions appear to be divided into four camps:
1 - People who are planning on buying a bike designed around a long stem, buying a larger size to gain stability and reach, then switching out to a smaller stem to improve descending capabilities without sacrificing riding position.
2 - People who are happy with their current frame/stem length and will buy the same next time the new bike fairy beckons.
3 - People who have no idea what I am talking about, and will follow dealer or manufacturer recommendations for their body size.
4 - People who are looking to buy a bike with more contemporary geometry, designed around a longer reach and supplied with a short stem. So...