- #1
TeddyRoxpin
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When trying to abruptly stop a motorcycle that is in motion, can engine braking actually have a negative effect on the rate of deceleration?
Scenario: a motorcycle is traveling down a straight highway at 100mph in 6th gear and needs to perform an emergency stop. The weather is clear and road conditions are perfect (i.e. no oil or debris on the road).
Question: will the bike stop faster if the rider pulls the clutch in AND engages the front brake? OR will the bike stop faster if the rider only engages the front brake?
(We'll say that the motorcycle's speed in 6th gear while the engine is idling is 15mph so, for the purposes of this scenario, we will consider 15mph as "stopped" because below that speed the idling will certainly produce forward force)
Fact: front brakes are most effective in slowing down a motorcycle due to weight transfer to the front wheel.
Engine braking is also effective but the force is exerted on the rear wheel only and the rate of deceleration provided is not nearly as high.
So, let's say maximum front brakes slow the motorcycle down at a rate of X.
And let's say engine braking slows the motorcycle at a rate of Y.
X > Y
So, is it possible that Y has a 'negative' impact on X and, therefore, the bike would actually stop in a shorter distance if the rider clutches IN and only uses front brakes? Or will Y (engine braking rate of deceleration) always provide additional deceleration (in 6th gear which at lower speeds does not provide a large rate of deceleration) and actually has a 'positive' impact on X and therefore will always stop the bike in a shorter distance when using both front brakes and engine braking ?
Someone please enlighten me. Initially, I thought engine braking *could* have a negative impact the rate of deceleration of the bike under heavy braking (using front brakes) but now I'm not so sure
Also please consider the difference characteristics of a sport bike vs a cruiser if that has any bearing on the response.
Thanks!
EDIT: Perhaps a better fitting scenario is:
2 riders on identical bikes accelerate to redline in 3rd gear, hold redline for 3 seconds, then perform heavy braking. Rider 1 clutches in and only uses front and rear brakes. Rider 2 leaves 3rd gear engaged and uses front and rear brakes. Assuming there is no skidding or loss of road contact with the rear tires, who stops faster?
(If it's not clear, basically, I'm trying to determine, from a physics standpoint, if adding "engine braking" can actually cause a bike to take longer to stop in certain circumstances. i.e. when braking force (from use of front and rear brakes) is greater than engine braking force. Because, of course, if a rider is only applying a little bit of brakes, engine braking will *assist* in slowing down the bike)
Scenario: a motorcycle is traveling down a straight highway at 100mph in 6th gear and needs to perform an emergency stop. The weather is clear and road conditions are perfect (i.e. no oil or debris on the road).
Question: will the bike stop faster if the rider pulls the clutch in AND engages the front brake? OR will the bike stop faster if the rider only engages the front brake?
(We'll say that the motorcycle's speed in 6th gear while the engine is idling is 15mph so, for the purposes of this scenario, we will consider 15mph as "stopped" because below that speed the idling will certainly produce forward force)
Fact: front brakes are most effective in slowing down a motorcycle due to weight transfer to the front wheel.
Engine braking is also effective but the force is exerted on the rear wheel only and the rate of deceleration provided is not nearly as high.
So, let's say maximum front brakes slow the motorcycle down at a rate of X.
And let's say engine braking slows the motorcycle at a rate of Y.
X > Y
So, is it possible that Y has a 'negative' impact on X and, therefore, the bike would actually stop in a shorter distance if the rider clutches IN and only uses front brakes? Or will Y (engine braking rate of deceleration) always provide additional deceleration (in 6th gear which at lower speeds does not provide a large rate of deceleration) and actually has a 'positive' impact on X and therefore will always stop the bike in a shorter distance when using both front brakes and engine braking ?
Someone please enlighten me. Initially, I thought engine braking *could* have a negative impact the rate of deceleration of the bike under heavy braking (using front brakes) but now I'm not so sure
Also please consider the difference characteristics of a sport bike vs a cruiser if that has any bearing on the response.
Thanks!
EDIT: Perhaps a better fitting scenario is:
2 riders on identical bikes accelerate to redline in 3rd gear, hold redline for 3 seconds, then perform heavy braking. Rider 1 clutches in and only uses front and rear brakes. Rider 2 leaves 3rd gear engaged and uses front and rear brakes. Assuming there is no skidding or loss of road contact with the rear tires, who stops faster?
(If it's not clear, basically, I'm trying to determine, from a physics standpoint, if adding "engine braking" can actually cause a bike to take longer to stop in certain circumstances. i.e. when braking force (from use of front and rear brakes) is greater than engine braking force. Because, of course, if a rider is only applying a little bit of brakes, engine braking will *assist* in slowing down the bike)
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