Posted: Sun May 15, 2005 11:24 pm
Here's a little explanation of grip in relation to braking....
Ok, I'm assuming you are aware that if you press harder on a surface, it's creates more grip.
How it works,
Braking with the back brake: using the trailing brake, exerts a pulling force on the frame of the bike, where the frame is actually pulling the rear tyre forwards and (due to the suspension) slightly upwards, lessening the effect of gravity, (which is what gives you your grip on the road).
Braking with the front brake: Because the front forks are angled, rather than vertical, any braking done, using the front brake, will cause some of the braking force of the bike, to be redirected in a downwards direction, pushing the front tyre into the ground. This gives you more grip, enabling you to brake harder, without sliding.
For example, if the front forks are angled at 30 degrees, and assuming a braking force of 2g. The extra downwards force is equal to
2g X Sin(30) X Cos(30) = 2g X 0.433 = 0.866g
this means that the total downwards force is 0.866g, + normal gravity (1g) = 1.866g
Essentially doubling your grip on the road!
This however is only a rough guide, as it doesn't take into account that the forks compress, reducing their angle to the road.
What this means is the best way to stop is to use the front brake heavily, and use the rear to scrub a cheeky little extra speed off at the same time.
However on very slippy surfaces, you will not be able to use the front brake hard enough to make this a noticable effect, in which case, you should find that using both brakes with equal pressure works the best.
I hope this gives you an understanding of what works best, and why? (and hence how it should feel on the bike - nose diving into the ground)
Andy
Ok, I'm assuming you are aware that if you press harder on a surface, it's creates more grip.
How it works,
Braking with the back brake: using the trailing brake, exerts a pulling force on the frame of the bike, where the frame is actually pulling the rear tyre forwards and (due to the suspension) slightly upwards, lessening the effect of gravity, (which is what gives you your grip on the road).
Braking with the front brake: Because the front forks are angled, rather than vertical, any braking done, using the front brake, will cause some of the braking force of the bike, to be redirected in a downwards direction, pushing the front tyre into the ground. This gives you more grip, enabling you to brake harder, without sliding.
For example, if the front forks are angled at 30 degrees, and assuming a braking force of 2g. The extra downwards force is equal to
2g X Sin(30) X Cos(30) = 2g X 0.433 = 0.866g
this means that the total downwards force is 0.866g, + normal gravity (1g) = 1.866g
Essentially doubling your grip on the road!
This however is only a rough guide, as it doesn't take into account that the forks compress, reducing their angle to the road.
What this means is the best way to stop is to use the front brake heavily, and use the rear to scrub a cheeky little extra speed off at the same time.
However on very slippy surfaces, you will not be able to use the front brake hard enough to make this a noticable effect, in which case, you should find that using both brakes with equal pressure works the best.
I hope this gives you an understanding of what works best, and why? (and hence how it should feel on the bike - nose diving into the ground)
Andy