Just a quick general question, I recently started playing with an old Pentax SLR and am trying to figure out what shutter speeds are best (as a general rule) for well lit close up shots as well as less well lit stuff such as indoor skateparks.

If you use a flash, that will help immensely in "freezing" the action. So if you'd used a flash on him, he'd be sharp but then you'd get some motion blur. I like that pic alot, compositionally, its really nice, sky's good too.

Actually looking at it, do I detect a little bit of flash reflecting back on the front spokes? Or is that just some ambient light from the side?

If you don't have a flash, or don't want to use one, then its a case of a faster shutter speed. What speed was that? Maybe 1/60th? I'm guessing here but I'd suggest trying 1/125 and have a play around with that, and see how you go on. If its low light, you would need to use a faster film to compensate (if not using flash), say 400 ASA on a dull day/early evening when the suns on the wane.

Try shooting a higher ISO film to gain you a slightly quicker shutter, try 400.

At 3.5 max aperture you mayaswell shoot wide open. This will help in isolating the rider from the background, and allow the most light in for the fastest shutter you can then use and still get a correct exposure.

I don't like to shoot action under 1/250th of a sec, as motion blur is always a worry at anything slower.

If you want to go the flash freezing route, i would suggest a much slower shutter. Shots where flash is used to freeze the rider, but its still just a bit slow to have a slight blur, makes everything look fuzzy. Whereas if the blur is much larger, and the area frozen by flash much more defined, i find this effect more obvious, and therefore more pleasing.

Oh and what focal length is your lens? This will play a huge part. As obviously the more zoomed in, the more camera shake and other general movements are amplified, and therefore the quicker shutter speed you need to freeze the image.

Nice arse....Ahem....

(sorry, but bad jokes just flow out of me )

no ones stated the obvious yet although someone mentioned ISO speeds.
buy the fastest film you can get. i used to use about 400 to 800 for colour and 1600 to 3200 for black and white. this will allow you to get nice crisp shots dull daylight without a flash. perfect for outdoor bike pics. the higher the number the quicker the film absorbs light so a higher number allows you to use much shorter exposure times (faster shutter speeds)
then you set your cameras ISO speed to match the speed of your film which will give you an accurate indication of what aperture you should be using and whether or not the current apeture and shutter setting will give a correctly exposed picture, assuming your camera has indicators to tell you this stuff. if you just bump up the ISO setting without changing your film your camera will allow you to use faster shutter speeds which will under expose a slow film.
if you want to blow your pictures up be aware that the grain in a faster film will be more visible.

Cheers for the help people
am off using some aso400 film today and am gonna manually set the shutter speed a bit faster, will see how things go!

I tried it with ASA400, seems to be a lot better
They are grainy because the developers forgot to put them onto CD for me (despite me paying them) and I had to scan them with a less than ace scanner, anyways
Riding
Few from round and about the area I live

Its an old railway siding near the transporter bridge, kinda a place where old rolling stock comes to die.  From a saftey perspective I never crossed the lines, just stood next to the most knackered one and had a few snaps at it,