just been given a trainer by a friend, but it came with no instructions (he never used it). Basically, how tight do I make the roller at the back.
DO you just do it to suit yourself, or is there a correct tightness? I'm guessing, too lose and the speed/average speed on the speedo will be out, but I'm unsure how tight and as such, how much resistance there should be.

I've owned 4 different trainers and each one is different. But there are some techniques that I've learned through trial and error that work well for me no matter what trainer I'm using. First, make sure that you have ample pressure in your tire - the best is to get it close to maximum pressure. Make sure you have a skewer that fits tightly into the cups - many skewers don't fit to well into the cups. Then, tighten the resistance unit a little by little. Between each little adjustment, grab the rear wheel firmly and quickly jerk up and down. When you get to the point that you can do this without the wheel slipping on the resistance unit, you have the right tightness.

Many thanks.