I just picked up a K10D about 6 months ago and I love it. I am into mountain biking as well and it works great. In the time it takes to move your finger from the on switch to the shutter you can take a picture.as long as you are not using more than a 1 second exposure there really is no down time between pictures.I went out with someone who had just gotten a Nikon D70 and he was having a hard time getting the camera ready fast enough for the second rider coming down the hill. I spent $1300Cdn for the body and a 18-55 Pentax lens. The build is very sturdy, so no need to be too gentle with it. I haven't gotten it wet yet, but I hear it holds up to it's claims. It is heavier than some SLRs, but I personally am will to make that sacrifice for the extra durability. I also find the picture quality great. Take a look at the reviews on this sight people say a lot of really nice things about it.