This is a report of what I have seen on a Fast cross country bike tour at 120 to 150 miles/day.
There were 30 bikers. Of those, three were Vegetarians. (perhaps more but did not reveal it) These three Vegetarians were noticeably more skinny and were not part of the fast group. However, one woman was faster than most guys.
The rest of the bikers followed a high Carb diet while biking followed with a recovery drink right after stopping for the day. I used Chocolate Milkshake and so did most.
The Vegetarians used Coca Cola.
All 30 bikers finished the 3000 mile ride without injury in 25 biking days.