Bicycling and Balance: A question

Which is easy: To maintain your balance when cycling uphill, or when cycling downhill? Assume you maintain a constant speed of 6 km/hr and the inclination is constant. If you like to challenge your proficiency in physics, assume further that you are negotiating a bend.

I don't know the answer so I am hoping someone would explain in a way I and others can understand.

This question came up when I was negotiating a small bridge over a brook on my usual cycling route. As you come off the bridge you have to veer to the right sharply. I find it harder to maintain balance on the downhill climb than the uphill climb (which I do when I return) during this sharp turn.

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It's not a question of uphill or downhill. The issue is the speed you are traveling at and negotiating the turn.

When you turn on your bike, part of your momentum is carrying you in the direction you used to be going (I hope that makes sense). For example, if you are trying to turn right, your momentum is trying to pull you to the left. To compensate you will find yourself "leaning in" to the turn automatically.

The faster you are going, the greater the force pulling you in the old direction.

I hope that explanation floats. It is a bit sloppy since I didn't want to talk about vectors. :-)

(I also think the "constant speed on an incline" is a tricky phrasing. When you're on an incline, gravity is trying to pull you down the incline. To go uphill, you need to exert force to not slow down. To go downhill, you need to exert force to not speed up!)

When making a turn while going downhill, the road has a negative effective camber, and positive for uphill turns. I suggest you get somebody to videotape you making the turns, along the plane between your wheel axles so you can measure effective frame angle to road and observe the movement of your body.

d, I'll ask the wife to record my ride. It's an excellent idea. (First time I've encountered the term 'camber', btw. Had to look it up)

I find it harder to maintain balance on the downhill climb than the uphill climb (which I do when I return)

Many cyclists find that they have a preferred direction of turning meaning that no matter the incline, when cornering under high demand conditions one finds it "easier" to turn right versus left or left versus right. So you'll need to balance direction of turn across gradient conditions in your experimental design.....

The one thing that has not been mentioned is the effect of braking while going downhill. If front and back brakes are applied equally, little or no compensation is needed. However, if one uses the front or back brake almost exclusively, there will be differences in friction between the tires and the road - especially a problem with the back brake and skidding. Another small factor is the compensation that is needed in the upper body for balance if one brake is used exclusively.

And why are you only going 6 kph downhill anyway?;-)

By natural cynic (not verified) on 06 Jun 2008 #permalink