Rear Brake Braking

[mgarl10024]

Hi,

I'm reading Cyclecraft after many of the good reviews on here.

On pg.53, he says "A cycle takes more than twice as far to stop using only the rear brake compared to using only the front brake".
It got me thinking as to why this would be? The blocks are often the same, the mechanism is often the same...
I understand that using the front brake can lift the back wheel up, reducing the rear's effectiveness, but I don't think this is what he means here.
Is it losses in the cable - meaning that someone can only pull half as hard and exert half the pressure on the blocks on the rear compared to those on the front?

Thanks,

 

[Smokin Joe]

It's the same for all vehicles, in fact I'd be surprised if a bike could actually stop in half the time using the rear instead of the front. When you use a front brake the weight of the bike is thrown forward and down onto the tyre, causing it to compress and bite into the surface. The rear brake will operate on the rim with just as much force but because no weight is going down onto the tyre the back wheel will lock with very little pressure.

 

[GrasB]

As Smokin Joe said. When you apply the front brake the harder you brake the harder you can brake before you break traction. With the rear wheel the harder you brake the less you can brake before breaking traction. Net result is typically the rear brake is traction limited, the front brake is torsional reaction limited, otherwise known as going over the handlebars.

 

[Fab Foodie]

For a good explaination, see Sheldon the Guru...

http://www.sheldonbrown.com/brakturn.html

There is good reason why many cars have disc brakes on the front wheels and drums on the rear. Or take a look at motorcycles, vast paired discs up front, tiddly drum or small disc on the rear. It's the front wheel that does most of the braking... it's why fixies without brakes are a really dumb idea even if you can leg-brake the rear.

 

[mgarl10024]

Hi Smokin Joe, GrasB and Fab Foodie,

Thanks very much for your replies - what you've said makes a lot of sense as I had not considered the weight shifting, so thanks for pointing that out.

Thanks,

MG