[Leica] I'd like advice on shooting a fleeting moment of a bike race

[abridge at gmail.com (Adam Bridge)]

The Tour of California blitzes through Davis tomorrow about 1 PM and I
have a spot all picked out. I'll have only a few seconds for the shot
but I thought the pros who have done this sort of thing before might
have ideas on how to properly set up.

I'm going to shoot looking up an overpass from it's base. I figure the
cyclists will have heads mostly down at this point, perhaps looking
around for position but it's a good place for good aerodynamics so I'm
thinking they'll be pretty well tucked in.

I'm shooting with the 560 on the 1Ds MKII since I have to be almost a
block away although I'm taking a couple other lenses just in case and
then the M to grab a few shots as they zip past, probably with the CV
15 or 28.

Still, if there are things I could do to help increase my chances for
a good shot, or maybe eliminate common failures, those of you who have
made $$$'s doing this might offer a few suggestions for this rookie??

Thank you!

Adam