Originally Posted by
veloGeezer
There's people who go to these things and take them really seriously
Those are the same folks who (in their mind at least) think they are racing you on the MUP.
>>
Is it acceptable for me to just show up and ride and not worry about joining and/or riding with a group?<<
It's not only acceptable, I'd say that's pretty much expected for most folks. It is nice to ride with a few folks to strike up a conversation and do a little drafting (do alot if it is windy!) I've also found that you typically don't ride with the same people the whole time anyway for even if you start out with a certain group that rides at your pace, at mile 50 or 80 they or you may slow down, or maybe stop to rest longer than you want, so maybe you'll find yourself with a different group and/or going solo at some point.
Overall, just have fun and ride at your own pace.