Depends on what lenses u using. The sprint pro can hold my S3 Pro (definitely bigger than ur D70) with 18-70. But just that u better don tilt it at other angles (besides the landscape, flat angle) as there maybe stability issues. Overall, i think if u wan a light tripod, this is a good choice.
buy those ballhead mounted on a "C" clamp type lor. like that just clamp onto the bike, put down the bike stand, mount the camera, aim, use mirror lockup with timer, compose the shot and fire away!!:thumbsup:
Yup, 725B should be good. I used to have a 724B (predecessor of the 725B) and it's really light and short for carrying around. Comes with a tripod bag too. Can easily handle the D70 with kit lens and a flash.
But if you want something that will support a big lens and light, go for CF tripods. But that will fall outside your budget. The 724B that I had was a little unstable with the D70 and a 70-200 Sigma.