A week and a half ago, I rode 106 miles on the industrial cruisr bike seen in my avatar photo. Now, I didn't have to do it again the next day, but still it helps show that the bike isn't quite that critical.

If your bike is working and is comfortable, you're fine. If you want a better one, go for it. If people are riding faster, that's liable to be more because of the people than the bikes. I've passed some awfully nice bikes on my cruiser. (I wasn't fast, they were slow).

If you haven't done it, work up to some longer rides, and try at least one 100 mile ride several weeks prior to your long ride and see how you feel.

Check the elevations on the 190 mile ride to make sure it isn't hillier than where you normally ride.

I don't see any water bottle holders. Figure out how to carry some water along.