Hi Chris,
I used to shoot a lot of cycling back in the 80s & 90s mainly road & MTBiking but also TTs.
If you can get there early, go to the HQ and get a copy of the startsheet, generally the riders who are expected to do well will be sent off on the 10 numbers (10,20,30, etc) or on the 5 numbers (5,15, 25 ) with the highest seeded rider normally sent off last. Competitors are sent off at one minute (as a rule) intervals.
Also if you don't know the course you should be able to get a description or map at HQ if this is not on the startsheet.
Try & drive out to get a look at the course or at least part of it before the start, short, sharp hills are always good as a lot of the riders will get out of the saddle to keep using the big gears & you should get some good grimacing shots. If these hills are on a long bend that can also be pleasing to the eye. Always look for clean backgrounds without road signs or wheely bins or other unsightly rubbish. A famous photographer (I can't remember who

) said the most important part of a picture is the background, now while I wouldn't agree entirely with this it is very, very important.
Shoot as wide as your lens will let you, even if the background is blurred out if it's a good one you will still get the feel of it in the shot & it will help to blur out any cars behind the riders.
Riders coming towards you you can use a slightly higher shutter speed, I normally try to go for at least 500sec with a 3 or 400mm lens if I want to guarantee they'll be sharp.
If its an out & back course you can get a shot from side on, on the opposite side of the road as they come back past you if you've managed to pick a good spot with a reasonable background.
Side on or half side on shots try to lower the shutter speed to get a bit of blur in the wheels 350sec or slower if you feel confident with your panning.
Get as low as you can, the riders will look more impressive.
Be aware that during the race depending how far you are into the course there will be riders who have been caught by faster riders from behind, & riders who haven't started will have messed up the order of the competitors coming past you. If you get the chance take a shot of the back of them immediately after they have passed you (they will have their no. on the rear of their skinsuit) so you can marry up names & numbers from the startsheet later for captioning.
Luck,
Stew