I am often asked about standing vs sitting on hill climbs on the bike. This is an article from some time back that addresses this matter. Realize there are different answers, to some extent, if you are doing a triathlon/time trial or a road race.
Should a rider should sit or stand when climbing a hill on a bike? I wish I could give a one-word answer, but that isn’t possible. As I’ve said so many times here in responding to reader questions, the answer must often start with “it depends.” This one is no different. Here’s what this answer depends on…
Steepness. Low gradient hills are usually done seated. Steep hills often demand some standing. And the steeper the hill is, the more likely you are to stand up. When standing on a steep hill your body weight takes some of load off of the leg muscles. On the other hand, it tends to stress the aerobic system more. As a result you’ll probably breathe harder and have a higher heart rate when standing. But the steeper the hill is the less difference there will be when it comes to muscular- (seated) vs aerobic- (standing) system stress.
Hill length. The shorter the hill, the more advantage you will have by getting out of the saddle. You’ll create more power (again, because of adding body weight to the pedals) and get over it quicker.
Type of event. On low-gradient hills a triathlete or time trialist is less likely to get out of the saddle than a road racer. This is primarily due to the variably paced nature of road racing (as opposed to the steady-state riding of triathletes and TTers). If another member of the peloton or break is accelerating up the hill, you are often forced to accelerate to keep pace, or risk being dropped. A quick acceleration on a hill usually requires standing.
Body mass. The lower your body mass the more advantageous it is to stand on a climb. The greater your mass the better off you’ll be staying seated. One quick and simple way to come up with your body mass is to divide your weight in pounds (1kg = 2.2lbs) by your height in inches (1cm = 0.4in). So if you weigh 154 pounds (70kg) and you are 72 inches (180cm) tall your “mass” is 2.13 (154 / 72 = 2.13). I’ve found that for males the best climbers are at less than 2.0. These folks should stand a lot (think of Marco Pantani). Men in the range of 2.0 to 2.3 tend to alternate between standing and sitting a lot (for example, Lance Armstrong). Those men at 2.3 to 2.5 are best advised to sit a lot (like Miguel Indurain). Folks over 2.5 usually avoid hills. Women should use a scale which is about 0.2 lbs/in less (for example, under 1.8 are typically good climbers).
So, losing (or gaining) weight may change how you climb – and how well you climb. For example, a 1kg (2.2 lbs) loss of weight (bike and/or body) allows you to climb a 1000m hill with a 10% grade about 3 to 4 seconds faster than when heavier at the same power output. Another way of looking at this is that 1kg of body weight is roughly 3w on a climb (so 1lb is about 1.5w).
Speed. At about 12mph (20kph) or faster staying seated and in an aero position if in a time trial or triathlon is usually a good idea. If your speed is less than 12mph then sitting up or standing is often better (depending on mass). This is affected, however, by the wind. A headwind obviously reduces your speed and a tailwind increases it.
Fatigue. On long climbs, especially those late in the race, there may be some advantage to alternating standing and sitting to relieve muscle fatigue. Even if all of the other considerations listed here indicate you should stay seated, but the muscles you use to drive the pedals when seated are very tired, you may need to stand simply to give them a break.
Gearing. This is related to steepness. If you are on a hill but your gearing is so high that cadence bogs down (slow turnover) you may need to stand in order to keep the gears ticking over.
Mountain bike. Standing causes the back wheel to lose traction when riding off-road on a steep hill on loose gravel, sand, or wet roots. So staying in the saddle is recommended for such climbs on a mountain bike. Pedaling while seated produces more even tension on the chain throughout the stroke and that helps to prevent wheel slippage.
The good news here is that you can basically trust your instincts on hills in races. In most of the above situations your body will tell you when you need to stand or sit. It’s really not a great mystery – unless you overthink it. In this case, experience is the best teacher.
Training on hills should involve both sitting and standing. Sitting will help to build greater muscular force for riding on flat terrain. It’s a bit like doing squats. Standing may help boost your aerobic capacity, especially when the hill takes only two to three minutes to climb.