On Sep 8, 1:22 am, (Don Pearce) wrote:
On Sat, 08 Sep 2007 08:42:58 +0100, Eiron wrote:
Andre Jute wrote:

Those brakes aren't dodgy, Don, they're hyper-competent; what I forgot
to add is that they have a built-in modulator. They stop the one-
eighth of a ton of me and the bike and light touring gear from thirty
kph in 11 feet. I know, because I chewed up a pair of tyres while I
practiced that one to perfection. But I agree with you, for casual use
those roller brakes are overkill.

A fat man on a granny bike braking at over 1g!
Don't the laws of physics apply in Eire these days?

Quite so. That comes out at 1.05g. Centre of mass combined with
wheelbase tell us that he performed the last 8 feet of that stop flat
on his face in the road. But that is a perfectly legitimate way of
stopping your bike.

Anyone who wants to do the sum the easy way just pop this

(30 kph)^2 / (2 * 11 ft) in g

What's this nonsense, Don, a wiki written by you and the equally
useless Eiron? Didn't they teach you in tech school to use compatible
units? You're mixing Imperial and Metric measures hand over orange.
Here is a reliable authority on the subject:

"The maximum braking force that can be applied to a vehicle through
its wheels -- the mass of air having its own retarding force -- is
limited by the friction between the tire and the road, and is equal to
the weight of the vehicle multiplied by the coefficient of friction.
On a dry pavement, this coefficient could be as high as 1; with a
coefficient of unity, retardation would be 1g or 32.2ft/s^2 and the
stopping distance in feet would be V^2/29.9 where V is the speed in
mph. I must stress though that this is on an ideal surface such as
does not exist outside a test facility..."
(p98, Designing and Building Special Cars, by Andre Jute, Batsford,
London 1985)

That math is properly and correctly developed elsewhere in this
thread, where you can go find it.

into Google. I rarely use an other calculator these days.

You should learn how and you won't perpetrae further ****ups like in
this post.

Andre Jute
Our legislators managed to criminalize fox-hunting and smoking; when
they will get off their collective fat backside and criminalize
negative feedback? It is clearly consumed only by thickoes.