Its not that big for most, but I've been wanting this for months and it finally happened! I didnt set out to ride 100km, in fact I just had a pub lunch and decided to go for a short ride afterwards, and had about 4 hours till sundown so definitely wasnt planning a long ride but just kept on going, ended up in the dark (fortunately had my lights with me), the downside being I only brought a single banana and was definitely bonking the last 15km or so. But got there!
Lol indeed! and an early start, that could help :)