You should be in good shape with your experience shooting horse racing; the speeds are not dissimilar and some of the lighting challenges are common. When I’m shooting un-assisted I seldom use flash. The main lighting concern is avoiding bad shadows caused by the rider’s helmets over their face, but as you know its a delicate balance where flash can introduce an obviously artificial look to the action.
Choose locations if you can where the riders are approaching the sun, even if it’s high in the sky, there still may be bounce of the road unless it’s really black asphalt
Like your horses running, cyclists have positions during their pedalling motion (when the feet are close to 9 and 3) where they look dead, and action-stopping shutter speeds give the impression they might be doing a stationary trackstand.
I shoot shallow, anywhere from f2.5 to f4 almost exclusively and only stop down more when an industry client wants an entire bike to be in focus front to back. Unless you are tracking the subject you’ll need 1250th to stop action coming straight at you and much higher when it’s passing perpendicular to you.
If you are shooting tight, you’ll notice a lot of relative rider to bike movement during the pedalling motion (more when they get out the saddle). Put the focus on the rider’s face and keep it there in servo mode. Also make sure when shooting in either orientation you get the rider’s heads high up in your composition. Lots of newbies have tons of open frame about the cyclists heads and not enough legs and bikes.
When I shoot flash it involves multiple speedlites and hi-speed sync to let me add just a hint of fill while reducing recycle times. A long throw reflector held by an assistant off axis is necessary, hence my suggestion to forget about flash if you are trying to shoot a race by yourself.
The guys who shoot from motors all the time do have on-camera flash fill but that’s just to ensure they get a higher percentage of sharp shots. Most of the time the stuff looks artificia