My dad is going to start riding soon, which I am very happy about. He asked asked me what I ate on my rides and I told him.... fruit, energy bars, sometimes gu, etc. He is worried about sugar intake and avoids it all cost because of his medical conditions. He asked me what he should eat while doing long rides.

I told him fruit but to be honest, I dont know! Fruit provides a short burst of energy (I think at least).

What else might be sugar free but provide a lot of energy for riding?