Jimboallee

[Dave5N]

Please explain mechanical advantage to us.

Road brakes worked by v-brake levers don't work very well - there isn't much power.

With road brake systems, there's a lot of leverage in the lever, but not much in the caliper.
With V-brakes, there's not much leverage in the lever, but a lot at the brake.

With a V lever and road calipers there's not much leverage so you have to squeeze very hard.
With a road lever and V-brakes, there's lots of available power, but the blocks move such a short distance that they are only usable on very true wheels for a fairly short time (after which the cable needs adjusting).

 

[andrew_s]

The ratio between the movement at the input end of a mechanical system and that at the output end. If there were no losses the ratio in the forces would be the inverse.

In brakes, the ratio for the system as a whole is between how far you pull the lever and how far the brake blocks move. You pull the brake lever 2", the brake blocks move 1/4", and the blocks squeeze the rim 8 times as hard as you are squeezing the lever.

In a road brake, it's more like the 2" of lever travel pulls 1/2" of cable with 4 times the hand pressure, and the 1/2" of cable travel moves the blocks 1/4".
In a V brake, 2" of lever travel pulls 1" of cable with twice the hand pressure, and the 1" of cable travel moves the blocks 1/4".

With road levers and V brakes, you get 2" lever travel moving the blocks 1/8" with 16x hand pressure.
With V levers and road brakes, 2" of lever travel moves the blocks 1/2" with 4x hand pressure.

That's the ideal situation, and is never realised in practice. The various intervening components flex, compress and drag so you end up with less force.
V-brakes are generally more powerful because the lower cable tension causes less flex and compression.

 

[Garz]

Mumbo jimbo on this would be nice!

 

[jimboalee]

Andrew_s explains it excellently.

 

[jimboalee]

Mumbo jimbo on this would be nice!

I can't be bothered with bicycle brakes right now. I'm working on the principle of Isospin in Mesons to develop a metal that is independant of gravitational influences.

 

[Garz]

..which can be called jimbon fibre!

 

[jimboalee]

On this planet, it will be called Hermesonium.

From the Greek god Hermes, flighted god of knowledge; and Meson, the sub atomic hadron Quark-antiQuark particle that makes it all possible.

 

[Dave5N]

On this planet, it will be called Hermesonium.

From the Greek god Hermes, flighted god of knowledge; and Meson, the sub atomic hadron Quark-antiQuark particle that makes it all possible.

JESUS CHRIST I asked about mechanical advantage. Get to it, Man!

I want Newton, not Einstein!

 

[normgow]

As Andrew_S said:
Mechanical advantage is distance moved by effort divided by distance moved by load.

 

[bonj2]

opposite of velocity ratio.