motorcycle weight vs. stopping distance
- Thread starter kml
- Start date
Alsterbator
Registered
To answer your question directly, No it doesn't.
The rider is ultimately the single biggest factor in total stopping distance.
The rider is ultimately the single biggest factor in total stopping distance.
bigoltool
Registered
Alsterbator
Registered
Not really...
Weight affects your ability to stop in TWO ways:
* It takes more energy (braking) to slow a heavier weight
* Traction INCREASES as a result of added weight such that more braking can be used without starting a skid.
Adding weight essentially CANCELS itself out as an impact on stopping distance. All that you need to do is apply your brakes harder in order to TOTALLY compensate for added weight.
But, generally speaking, weight makes no difference in stopping distance because the brakes are more than adequate to handle any normal range of weight for that bike.
Like I said, the rider is the biggest factor here.
Alsterbator
Registered
KML I believed asked a loaded question, one that he felt most would answer incorrectly... so far he is right.
I would suggest that anyone that thinks otherwise do a lil more research before going with what you believe to be common sense, after all it's not that common.
I would suggest that anyone that thinks otherwise do a lil more research before going with what you believe to be common sense, after all it's not that common.
kairles
Donating Member
you say no, then you say yes?
he said "during a maximum braking event". If hes just riding around town sure he can brake earlier and/or harder to compensate for any added weight, but in a maximum braking event you cant brake earlier or harder
Alsterbator
Registered
Hence why I said"
Even with the added weight the motorcycle is still capable of stopping in the same distance.
Maximum braking doesn't mean that you squeeze and press as hard as you can... Maximum braking is at the threshold right before loss of control, it is achieved through the quickness and progressiveness of the squeeze. Added weight enables you to squeeze more in less time, thus compensating for the added mass. The question is "DOES increasing a motorcycle's weight increase the stopping distance for a given speed during a maximum braking event.". (Adding weight in and of itself does not, answer is No). Not "CAN increasing a motorcycle's weight increase the stopping distance for a given speed during a maximum braking event." (Adding weight when a rider lacks confidence or experience in braking situations, answer is Yes, the motorcycle is still capable it's the rider that isn't). The bikes capable of more than what the average rider can give it. In other words, the rider is the weakest link.
Lets rationalize it:
You apply both brakes (the front and the back) gradually and with almost equal force for the first phase of your braking.
The weight will transfer forwards as the front suspension compresses, and your arms bend, the front tire now bites into the pavement.
There's now more weight on the front, increased weight of motorcycle = more transferable weight = greater traction.
You now let off most - or all - of the rear brake and increase pressure on the front, which now has most or all of the grip. This middle phase of braking can be 100%:0% - if it is less than 85% Front, you probably aren't braking near your bike's limits.
The bike slows and the forces you are exerting through the brakes and tires diminish (the energy in the bike is proportional to the square of your speed).
The front begins to rise back up on its suspension.
You taper off on the front brake - to prevent a slow speed lock up - and increase the rear brake pressure once more.
HT_USMC
Registered
It is not only related to the coefficient of friction of the tires. It is also related to the brakes and the braking system!
First, the force that could be applied through the tires is related directly to the mass: the force is proportional to the weight (the coefficient of friction is simply a constant in the equation.) If you double the weight, you double the braking potential OF THE TIRES. So as far as the tires are concerned, the weight should not change anything.
However the braking mechanism (the brake shoes/pads, the rotors, heat dissipation, etc) is another matter. When you load more weight onto a vehicle, that will have no compensating effect on the ability of the brakes to influence the speed of that vehicle. The brakes will be able to absorb about the same amount of energy as they did without the extra weight, so the heavy vehicle will not be able to stop nearly as quickly as the light vehicle; though the heavy vehicle will have better TRACTION.
And so, in practice, because of the limits of the braking mechanism itself, the mass of an object has a huge effect on the braking distance.
Simply put: If weight didn't change braking potential, you'd see dump trucks using the same brakes that a Toyota uses. There would only be a handful of brake parts/options/manufacturers. Yes, wheel size plays a roll in brake selection as well but I don't think that's an issue in this discussion.
First, the force that could be applied through the tires is related directly to the mass: the force is proportional to the weight (the coefficient of friction is simply a constant in the equation.) If you double the weight, you double the braking potential OF THE TIRES. So as far as the tires are concerned, the weight should not change anything.
However the braking mechanism (the brake shoes/pads, the rotors, heat dissipation, etc) is another matter. When you load more weight onto a vehicle, that will have no compensating effect on the ability of the brakes to influence the speed of that vehicle. The brakes will be able to absorb about the same amount of energy as they did without the extra weight, so the heavy vehicle will not be able to stop nearly as quickly as the light vehicle; though the heavy vehicle will have better TRACTION.
And so, in practice, because of the limits of the braking mechanism itself, the mass of an object has a huge effect on the braking distance.
Simply put: If weight didn't change braking potential, you'd see dump trucks using the same brakes that a Toyota uses. There would only be a handful of brake parts/options/manufacturers. Yes, wheel size plays a roll in brake selection as well but I don't think that's an issue in this discussion.
Alsterbator
Registered
When comparing ONE vehicle (motorcycle or not) with it's braking system, weight is not a factor.
Motorcycle "A" (carrying normal load) stops in 120ft
Motorcycle "A" (with added weight) stops in 120ft
Each vehicle will have it's own braking threshold (traction is the key factor) Maximum Braking is achieved at that threshold but not crossing it. Therefore for this question you can't compare one constant vehicle with different brakes or different vehicles with identical brakes.
Same vehicle, Same braking system, Same set of tires, Same rider... = adding weight not a factor.
If you change any one of those then weight could be a factor.
HT_USMC
Registered
I don't know where you got the different vehicle comparison. In the statement I made above it was a single vehicle. I just gave the example that the weight of the dump truck versus a car wouldn't be a factor, if the weight argument you make were reality.
If the right brakes are for the right vehicle, as you've stated, then what is the difference between the car and the dump truck that makes them have different brakes? Wheel base? Tire selection? Height? But not weight? Got it.
Brakes can only absorb a maximum amount of energy. Weight does not give the braking system the ability to bleed off additional energy. Tires and traction do not provide any additional stopping power to the braking system itself - they only allow the effects of braking to be potentially more reliable where that braking power meets the roadway. In fact, weight means the momentum of the vehicle is going to produce more potential (stored) energy due to the mass of the objects that are creating the additional weight, which the same brakes now have to stop. So, at the end of the day, the same vehicle under the same conditions with the same braking system, with added weight, and therefore added mass, will take longer to stop.
Your argument is the same as saying "it's the same engine and with twice the weight, it will continue to accelerate at the same rate it did without the added weight". Which, violates Newton's Second Law of Motion.
Traction does not equate to braking. Those are two independent forces that we are using collectively to apply stopping power (or more correctly, bleed off linear velocity - according to Newtonian Physics). Traction simply fights to increase the coefficient of friction and provides a way to apply the force of braking (produced by the braking system - not the tires) to the road's surface.
The only reason I've responded to this thread is because I don't want anyone to read this, load up their ride with saddle-bags full of items and think that they are in the clear to ride as they would have prior to the addition of the bags. It's just not reality.
Alsterbator
Registered
I don't know where you got the different vehicle comparison. In the statement I made above it was a single vehicle. I just gave the example that the weight of the dump truck versus a car wouldn't be a factor, if the weight argument you make were reality. The statement you made "If weight didn't change braking potential, you'd see dump trucks using the same brakes that a Toyota uses." appeared to be comparing the brakes of a dump truck to that of a car in a way that dump trucks should be able to stop in the same distance with the brakes that are on a Toyota.
If the right brakes are for the right vehicle, as you've stated, then what is the difference between the car and the dump truck that makes them have different brakes? Wheel base? Tire selection? Height? But not weight? Got it. GVWR, if the load being carried exceeds that then you potentially put yourself in a bad position.
Brakes can only absorb a maximum amount of energy. Weight does not give the braking system the ability to bleed off additional energy. Tires and traction do not provide any additional stopping power to the braking system itself - they only allow the effects of braking to be potentially more reliable where that braking power meets the roadway. Right, tires do not provide any additional stopping power to the braking system, they provide the necessary traction/friction to the road surface. In fact, weight means the momentum of the vehicle is going to produce more potential (stored) energy due to the mass of the objects that are creating the additional weight, which the same brakes now have to stop. So, at the end of the day, the same vehicle under the same conditions with the same braking system, with added weight, and therefore added mass, will take longer to stop. I would understand that if you were say... road racing, over a short time with extreamly repeated use the brakes most likely would loose some braking potential.
Your argument is the same as saying "it's the same engine and with twice the weight, it will continue to accelerate at the same rate it did without the added weight". Which, violates Newton's Second Law of Motion.
Traction does not equate to braking. Those are two independent forces that we are using collectively to apply stopping power (or more correctly, bleed off linear velocity - according to Newtonian Physics). Traction simply fights to increase the coefficient of friction and provides a way to apply the force of braking (produced by the braking system - not the tires) to the road's surface.
The only reason I've responded to this thread is because I don't want anyone to read this, load up their ride with saddle-bags full of items and think that they are in the clear to ride as they would have prior to the addition of the bags. It's just not reality. I agree 100%, you should never exceed the max load or GVWR cause a vehicles braking system may be inadequate.
The reality is that most people are quick to jump at what seems to be the most obvious or makes more sense, however that does not always provide them with the right answer.
The question is pretty direct, however when throwing additional factors it becomes more complex.
Great discussion BTW!
Similar threads
