I haven't done any long bike rides like that but I've done plenty of backpack trips and all-day adventure hikes, which have similar exertion levels and duration. I find if you are fat-adapted you need very little fuel during this kind of activity. I've used pemmican, but also I've used beef jerky, nuts and I once made melted dark chocolate mixed with coconut butter and macadamia nuts that were poured into muffin papers. Those got a little melty but were fairly tasty. A higher carb option I've enjoyed has been dates with cheese, but that was more of a treat than a necessity. I really don't need to eat a whole lot differently when I hike, and in fact, I seem to be able to get away with a little less food than normal.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting squat: 45lbs. Current squat: 145 x 4.