Why it is easier to get off the bike and walk up the steep road with it than riding it all the way up?
In: Physics
Because the gearing on your bike is not appropriate for the incline.
Consider how far the bike moves in one revolution of the pedals, to how far you move with one step with each leg. The amount of leg movement is approximately the same but you need to do more work per “step” with the bike because it travels longer and increases more in elevation.
The distance you push the pedal is not that long and work= force * distance means the force you need to apply with your legs is high, it might even be higher than the maximum force you can apply,
If you had gearing that made it possible to bike at the same speed as you walk and move the legs at the same rate it would feel quite similar to walking, the problem is at low speeds it is hard to balance a bike.
The work to go up a hill is to move against gravity and it will be equal so on a bike with to high gearing result in more of work per “step”
The reason this is not a problem on flat ground is there is no work required to keep constant elevation, you just need to overcome friction, drag, and other stuff that slow you down to keep a constant speed. When you walk on flat ground a large portion of the work is to move your legs and then moving them fewer times for the same distance on a bike is an advantage, as long as the force required on the bike is not to high.
If you use a bike with gears you will notice when you change them and try to keep the same speed that at low speed there is not a lot of force on the pedals but lots of work moving the legs quickly. At a high gear, the force gets high. You want around 1 revolution per second this is called the cadence.
There is another way to accomplish almost the same effect as lower gear is to take an alternate path with the bike. Have another road that is longer but will take the same time to bike up as it take to walk up the steep road. Then the work per unit of time = power is equal for both bike and walking, and it is close to equally hard.
This is why it is not uncommon for paths for bikes, wheelchairs prams etc to be a switchback or a long incline and at the same time there is a short path with steps when you walk,
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