Oooohhhh roadster is soooooo fun!!!!! It's my favorite, with a good fast horse. Actually, if you want a DRIVE you should try the Modern Shetland roadster ponies. I got to drive SweetOpal's National Grand Champion roadster pony and WOW it was a blast!!!
A good roadster horse should really like trotting fast without breaking into a canter. They really should have that "spark" and no hint of laziness. As for being built, a roadster horse should have a super extended trot and be able to set their heads. It does take a bit of conditioning as it is a demanding class, physically.
There is a jog trot, fairly slow/relaxed, a working trot (road gait), and then the horse will be asked to drive on, to drive at speed. The horse should show THREE DISTINCT trots, not just all fast trotting. That is what the judge really should focus on, besides general performance. Most judges tend to just place the horse that has the best "drive on", even if the horse is always at a fast road gait and never demonstrates a good jog trot, etc.
You also enter the ring the opposite direction as other horses.
It is F-U-N you shouldn't be afraid. Start at the local level, where there are fewer horses. I have to say I was a bit overwhelmed at Nationals with almost 30 horses in the ring, the B horses, it was QUITE an adrenaline rush but I did get a Top Ten with my gelding at the time!
Andrea