Need Help Shooting Cycling

I'm hoping that some of the cycling photographers might give me some help and share their tips about shooting road cycling.

Last night I tried to shoot a weekly time trial and wasn't too pleased with my results. It was getting a but dusky, so I decided to set up a station with two flashes -- a 580EX II on my camera and a 480EX slave on a tripod. I set my XTi to AServo focus and followed the riders to where the slave was pointed. I tried messing with exposures a bit but did most of the shooting at f4 and 125. I used my 24-105L lens, mostly at 105mm

At any rate, I'm not happy with the clarity or the exposure. Can anyone provide some guidance?

Here are some examples:

Shutter speed is a little low but can still get sharp photos at it. Try to max out your sync speed on your flash. Also set your focus point to top middle and keep it glued to the face like this.

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I tend to shoot between 1/100 and 1/250 but normally the slower end. I use One Shot AF and pre focus on a point then pan with the rider and fire just where you prefocused. When you are looking through the view finder follow with your eye the bit you want to be sharp (Normally the head)

Thanks Dan-o and Sheldona.

I'll try re-setting my focus button to the top as well as try some pre-focusing.

A question: what's the upper limit of high speed synch. Should f4 at 250 be OK?

I'm also new to using master / slave flashes. Is this a bad idea in general -- sort of last resort-- or am I better off with just on-camera flash in dusky conditions?

pmk

My 1DMIIn is 250. You can capture at a lower shutter just fine but your keeper rate will be lower. I started messing around with off camera stuff but I think direct flash looks pretty good. It takes practice but you'll get it. Also if you are shooting pans you don't need a high aperture so stop it down a bit the panning motion will get rid of the background.

Dan.

Thanks again, Dan-o. A quick websearch reveals that the XTi max'es out a 1/200. That should be plenty fast for most situations.

BTW: your cycling galleries are great.

Any other tips for cycling photography you think would be useful? I'm more used to MTB photography -- which is generally a nightmare because of the dappled lighting conditions.

pmk