# Bicycling up hill, high gear or low gear

by Hetware
Tags: bicycling, gear, hill
 P: 125 I know that the idealized problem using gears and force without considering biophysics will tell me there is basically no difference in energy between riding a bike up a hill in low or high gear. I have often wondered which actually uses more calories. Many people tend to go to a lower gear when going up hill. It feels easier. What I wonder is whether it really is easier in the long run. Of course, I am thinking within reasonable parameters so that there would be no physical injury due to putting excessive force on ones joints, etc.
 Sci Advisor P: 5,768 Off hand opinion: The amount of energy used would be the same. However in low gear the rider applies less force on the pedals, but has to move his legs faster in comparison to high gear, assuming the speed up the hill is the same.
 P: 785 The energy expent by you is the same (m * g * change in elevation). And so is the work (force * distance). But if you climb the hill in 10 minutes in top gear, and in 20 minutes in low gear, the difference is the power (work/time). You must be 'stronger' to pedal the bike in high gear. If you climb the hill in the same time, then the power would be the same too. That's all ignoring practical effects that may change your efficiency (standing on the pedals vs sitting, etc). Those things have to do with how hard your body works to make the pedals go around.
P: 5,768

## Bicycling up hill, high gear or low gear

When climbing in high gear you would need to apply much more force to the pedals than when climbing in low gear (for climbing in the same time). This is because in high gear the distance your feet travel is much less than in low gear. To get work (or energy) = force x distance to be the same, the extra power is needed.
 P: 30 more torque[low gear ratio] will get you up the hill more easily compared to less torque[high gear ratio].
 HW Helper P: 6,758 The work done is the same, but there's probably some optimal combination of speed and gearing, power x time, depending on the parameters of the rider, such as muscles, conditioning, ...
 Mentor P: 21,652 Remembering the relationship between energy and power and power and torque, if the energy is the same, a faster pedaling rpm will provide more power (over a pretty broad range of human pedalilng speeds) and get you up the hill faster. This also means that the proper gear to be in (in this idealized scenario) is independent of your speed up the hill! The proper gear to be in is a function of your weight (which determines how hard you can press on the pedal and thus your maximum torque) and the incline of the hill only.
 P: 827 Well people like motors work best at their ideal speed, if you need too much force, I am sure, that you need more energy, but I guess you should ask in a biology forum for exact numbers. An easy way to check is, which way you sweat more, because that body heat is all burned calories.
Mentor
P: 21,652
 Quote by 0xDEADBEEF Well people like motors work best at their ideal speed...
True - they are most efficient, meaning they produce the most energy output for the least energy input.
 ...if you need too much force, I am sure, that you need more energy, but I guess you should ask in a biology forum for exact numbers.
Notice that the sentence I wrote above doesn't mention force. Energy and force are not the same thing. And there is no such thing as "need too much force" in this problem because the the force generated is mostly dependent on the weight of the rider because you can't push down with more force than you weigh. In other words, the force is constant. But the energy is dependent on that force and the speed at which you are pedaling.
 P: 14 To compute Watts and Calories while riding up a hill, for every one revolution of a bicycle front tire, is this accurate? Watts = ma*gr*pcl*s*sin(theta) + Rr Calories = watts*0.2388459 m = Mass = 145kg a = Pedal Speed = 22pi/9 rad/sec gr = Gear Ratio = 44 : 18 (2.444 to 1) (This is gear ratio I use the most) pcl = Pedal Crank Length = .175m s = Front tire circumfrence = 2.2m Rr = Rolling Resistance ?? (I plan to gather Rr by comparing computed and measured data)
 P: 282 "because you can't push down with more force than you weigh. " Why so? :o
Mentor
P: 21,652
 Quote by sganesh88 "because you can't push down with more force than you weigh. " Why so? :o
Because you'll just make yourself stand up!
PF Patron