in message , Chris Malcolm
') wrote:

Simon Brooke writes:

in message , Tim McNamara
') wrote:

Ummm, no. The limit of braking power is not the force with which
the brake can clamp onto the rim, but the coefficient of friction
between
the tire and the riding surface. Clean dry pavement offers a higher
coefficient of friction than dirt with the same tires, although
perhaps pumice or slickrock might equal or exceed cement pavement.

Speaking as someone who regularly rides both types of bikes, I don't
agree with you. Mind you, I could be wrong - the caliper brakes on my
road bike are single pivot and not especially clever. I don't know the
extreme limits of braking on either system, since I'm now to old and
have too much respect for the fragility of my skull to just slam on
the anchors and see what happens. But I do know that I can stop
shorter - a lot shorter - on my hill bike than on my road bike, on the
same road and braking from the same speed.

I presume that on both bikes you can brake hard enough to skid the
front wheel.

No idea. I don't do so; perhaps I could, but like I say I have no
interest in the 'ejector seat' technique of coming to rest.

If you're higher off the ground on your road bike it won't be able to
stop as fast.

Don't think so. The saddles on all my bikes are the same height, modulo
normal suspension compression; likewise the handlebars. However the
angles on the hill bikes are a lot slacker, and I do habitually slip
off hte back of the saddle to brake hard on the hill bikes. So perhaps
the difference is just that I get my CoG further back.


--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
There's nae Gods, an there's precious few heroes
but there's plenty on the dole in th Land o th Leal;
And it's time now, tae sweep the future clear o
th lies o a past that we know wis never real.