Peter Clinch wrote:
DougC wrote:

The front tire should have /at/ /least/ the same contact patch are as
the rear, /if/ /not/ /more/.

Why?

I've never worried about this on any bike I've ever had, and I don't
recall ever suffering as a result, so it comes over as rather more
grounded in theory than practice.

I don't see why the front tyre needs calibrating to the rear. It
doesn't know what pressure the rear is running at or what the contact
patch is: shirley whether it will skid or not is down to absolutes, not
values relative to the back?

Pete.

This is mainly a recumbent/"alternate"-bike issue, as these bicycles
tend to have wider differences in weight distribution than upright bikes
do, and riders cannot shift their weight significantly during riding.

The reason that this is important is because if you enter a low-traction
situation and one of your tires begins to slide, you want it to be the
rear to slide first rather than the front. The rear tire will follow the
front tire, even if the rear tire is sliding. On a sandy road surface,
you can slide short distances with the rear wheel locked up and keep the
bike upright fairly easily--but it is damn near impossible to slide more
than a few inches with the front tire locked up (on either road bikes or
recumbents). Because of the front tire starts to slide, you cannot steer
at all and you have a far greater chance of crashing.

So (on a two-wheeled vehicle that is not a Segway) the front tire should
-always- have more traction than the rear. That means since the front is
carrying less weight, you run a lower front pressure so that the contact
patch is at least as large as the rear is.

And if you're running narrow tires, you can see some significant
handling gains by switching to a wider front tire as well. Narrow tires
do not handle loose surfaces well.
~