I've been at photography for about a year and a half now. Most of it has been landscapes, buildings, flowers and other stuff that doesn't move much! I think I am gettting better at it. Last night while out I came across a couple of dirt bikers who had set up a couple of ramps and were having a great time. I though what luck and stopped to take some pics.

I have a Rebel XT with a 70-200 lens and a17 -85lens. Both are IS. Well I was quite disappointed with the results. I know I didn't use the right settings, thus my question - what setting should I use to capture this type of action. I used the smaller lens and the light was good.

Thanks in advance for your guidance.