Joined
·
745 Posts
When bikers talk about braking, the mantra "the front wheel provides 75% of braking force" invariably comes up. I thought this might be a good time to talk about why: it all boils down to weight transfer.
If you've ever been to a drag race, you'll notice that the middle classes (e.g. Stock and Super Street) often don't have the nose-down/tail high look of the more powerful classes: instead the cars are jacked up at both ends, sitting pretty much level but higher than they would be on the street.
It's all about Physics: the higher the center of gravity, the more weight will be transferred to the rear wheels when the driver nails the gas. The more weight on the rear wheels, the more traction, and the less wheel spin.
Obviously, it's a tricky balance: too high and the car will wheelie off the line, too low and your launch turns into a burnout.
When you brake, the opposite is true - the weight gets transferred to the front end, lightening the rear in the process. However, this weight transfer does not happen instantaneously. The quickest stops will occur when the operator progressively brakes the vehicle, in this case your bike.
When you apply the front brake, the forks compress and the downward force on the front tire increases as the CG shifts forward. As it does, you can increase the force on the lever, which will add more downward pressure to the front tire, which means you can add more force to the lever, which means.... you get the picture.
Conversely, if you apply your maximum braking force on first grab, chances are you'll break the front tire loose - it hasn't started to load yet so it will slide.
As with everything else, it's a balance: even though the CBR250 has a single disc and less-sticky tires than a lot of bikes, you can still do a stoppie (rear wheel in the air) if you take progressive braking to the extreme.
Note also that as the front tire loads, the rear tire is unloading. As a result, you can apply more force to the rear brake in the initial stages of braking, easing off as the weight shifts forward.
Getting the maximum braking force out of a bike takes practice: find a parking lot with clean, consistent pavement and practice stopping, first from 15-20 mph and then from higher speeds (be sure to wear all of your gear). If you do, you'll be amazed and how quickly your bike can stop.
Last but not least, don't be naive enough to believe that you don't need this knowlege if you have ABS. Study after study (as well as the Honda CBR250 manual) note that an experienced rider can stop in shorter distances than ABS. I'm not discounting ABS as a good safety feature (and don't want to turn this topic into an argument about ABS), but if you want the maximum protection, learn how to use your brakes. If anything, ABS lets you get closer to the limits of adhesion without worry.
Ride safe!
If you've ever been to a drag race, you'll notice that the middle classes (e.g. Stock and Super Street) often don't have the nose-down/tail high look of the more powerful classes: instead the cars are jacked up at both ends, sitting pretty much level but higher than they would be on the street.
It's all about Physics: the higher the center of gravity, the more weight will be transferred to the rear wheels when the driver nails the gas. The more weight on the rear wheels, the more traction, and the less wheel spin.
Obviously, it's a tricky balance: too high and the car will wheelie off the line, too low and your launch turns into a burnout.
When you brake, the opposite is true - the weight gets transferred to the front end, lightening the rear in the process. However, this weight transfer does not happen instantaneously. The quickest stops will occur when the operator progressively brakes the vehicle, in this case your bike.
When you apply the front brake, the forks compress and the downward force on the front tire increases as the CG shifts forward. As it does, you can increase the force on the lever, which will add more downward pressure to the front tire, which means you can add more force to the lever, which means.... you get the picture.
Conversely, if you apply your maximum braking force on first grab, chances are you'll break the front tire loose - it hasn't started to load yet so it will slide.
As with everything else, it's a balance: even though the CBR250 has a single disc and less-sticky tires than a lot of bikes, you can still do a stoppie (rear wheel in the air) if you take progressive braking to the extreme.
Note also that as the front tire loads, the rear tire is unloading. As a result, you can apply more force to the rear brake in the initial stages of braking, easing off as the weight shifts forward.
Getting the maximum braking force out of a bike takes practice: find a parking lot with clean, consistent pavement and practice stopping, first from 15-20 mph and then from higher speeds (be sure to wear all of your gear). If you do, you'll be amazed and how quickly your bike can stop.
Last but not least, don't be naive enough to believe that you don't need this knowlege if you have ABS. Study after study (as well as the Honda CBR250 manual) note that an experienced rider can stop in shorter distances than ABS. I'm not discounting ABS as a good safety feature (and don't want to turn this topic into an argument about ABS), but if you want the maximum protection, learn how to use your brakes. If anything, ABS lets you get closer to the limits of adhesion without worry.
Ride safe!
