Originally Posted by GhostRider62

Depending on temperatures, one bottle is likely not enough. I did two hours today in 48F with one bottle and did not even finish it. On a hot day, I might need a bottle an hour. It would not hurt to bring a second bottle. Normally, I do not eat on a 3 hour ride but it sounds like your relative lack of training base would suggest bringing an emergency supply of food along and nibbling a bit as you go. It might not take much supplementary carbs.