A Question. When does one move up to the next group?
You are going to get a million opinions on that question
IMO: Everyone is different. Do you know the track inside/out? Can you anticipate other riders and navigate around them **without impacting them**? Does it seem like you are always passing everyone? What are your lap times? I also do happen to think the bike you are on should be a consideration, but I may be alone in this thought. There is something to consider when you are on a smaller cc'ed bike and considering moving into A-group. You need to be fast, you need to be predicable, and you need to be UNSHAKABLE. You will get passed close, VERYVERYCLOSE, but they will (usually) be good, clean, strong passes....usually, but not always (there are asshats everywhere

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Oh, and you need to be all adulty...no whining and complaining over the above mentioned passes or other "close calls." "Close" to you is probably totally under control for these peeps. if you move yourself into A-group, you are well aware that you are putting yourself with the fast, the faster, and the fastest....notice I didn't mention anything about them being all warm/fuzzy/snuggle bunnies?
I have been back & forth in both. Depending on where I am on different tracks, based on the cirteria above. There are pros & cons to both, and (IMO) different track day providers also tend to have different paces between A and B.....