The question of whether to sit or stand when riding uphill is usually an easy one for novice or recreational bike riders to answer: Standing is better because it makes you go faster. Besides, we look a lot cooler in the standing position, right? But it's a bit more complicated than that, and there are a few important factors to consider before making the decision to get up off your seat.
For starters, let's consider the relative energy expenditure of sitting versus standing on an uphill climb. Generally speaking, cyclists perform best when they are able to find a rhythm and stick with it. By remaining in a seated position while riding uphill, you may go a little slower, but you should be better able to maintain a consistent cadence over a long period. By standing up, your rhythm is immediately thrown off. That's because changing posture disrupts your riding momentum and increases your heart rate, making the ascent a lot harder.
In addition to your position on the bike, performance while riding uphill is partly dependent on your body type. Lighter riders typically climb hills faster than heavier ones. Conversely, larger ones tend to make up speed on the downhill portions of a ride.
When talking to experts about whether to sit or stand on an uphill climb, the response is often unequivocal -- "Keep your butt in the seat." However, dig a little deeper into the issue and most agree that there are certain occasions in which standing may be preferable or inevitable on a ride. For example, you may find that a very steep hill is extremely difficult or impossible to climb without standing. Some cyclists also choose to switch to a standing position for short sprints or even on modest hills in order to give their leg muscles a short break. In racing, attacks are often done in a standing position. These tactics are perfectly acceptable, as long as you keep in mind that standing is an unavoidable and temporary change in posture.
There are certainly other factors to consider in the decision to sit or stand while riding uphill, including whether you're properly geared as you climb. You should approach hills with a hard pedal in high gear (how high depends on the steepness of the hill), and be careful not to pull up so hard on the handlebars that you lift the front wheel. Of course, you must also be mentally geared for the climb. Riding uphill can be a challenge, even for experienced cyclists. Just take a deep breath, stay focused on the summit, and go for it.