Unless you’ve done something such that you have zero glycogen stores, you can get through an hour workout fasted. If you have full glycogen stores, that’ll be around 1300kj, very conservatively, and unless you’re a massively powerful hummingbird (all sugar) you won’t exhaust your stores.
And that’s a worst case.
What I’m not clear about is, if you’re as near zero-carb as it’s possible to get, e.g. just eating meat with no veg. at all, and have been for a long time (e.g. months), will you still have glycogen in your stores, due to gluconeogenesis (or other effect)?
correct you will be …
but like yesterday I did 245km ride and was craving sugar so had a couple of cokes. Now I have been fat adapted for a year, I never bonked or anywhere close to it but I just needed the top up. Now even I was on the bike for 10 hours then a few carbs like this will not harm and can only boost you.
Interesting, thanks. As a matter of interest, do you think some pieces of fruit might have hit the spot for you?
well I had a whole pack of jelly babies !
I guess when talking of these mega rides it is whatever suit you but anything under 100km just no need for anything
Oh well, you got in at least your “five a day”… 
Ok - thanks again.
That reminds me: someone (was it Vinnie Torich?) talked somewhere about a trick he used for getting up a climb he knew would be challenging. It was to pop something like a jelly bean into his mouth, but not eat it; maybe put it under his tongue. Actually it might have been a Polo mint, or equivalent. Anyway, that seemed to work for him. When he got over the brow of the hill, out would come the sweetie (whether spat out or saved for the next hill, I can’t remember 
).
wouldn’t all keto people have zero (or very very limited) glycogen stores?
I don’t think people on a ketogenic diet have no muscle or liver glycogen in the morning. I could be wrong but that is not my understanding. Happy to be corrected.
Why? They have normal blood sugar levels. By that reasoning people eating carbs should have no fat stores. 
you forget GNG surely ? the muscles get replenished and the FASTER study shows this, they need to be for me to get out of bed in the morning !
That’s what I am saying, but my wording was clumsy, so I can see how you didn’t understand.
I train regularly and mostly it’s fasted.
Weekends I’ll ramp it up a bit…
Saturdays will generally be a 100k ish bike ride 
Sundays can be anything up to a half marathon 
The rest of the week usually involves 1 to 2 hour long combinations of the above with some swimming 
thrown in and some gym work.
Biggest event I’ve done fasted is an Olympic tri and no fuel while racing either. Coincidentally, that particular one was my fastest time too.
Half ironman next. Stay tuned.
Not sure I would try a very long distance fasted though I am sure I would finish !
no I wont leave anything to chance with my first half iron.
if its anything like my first oly ill feel like shit afterwards!
I will eat on the morning and probably fuel up after the swim and prior to the run.
and the ley for any of us is to experiment and come to rest at what is best for you. I do believe Fasted rides are great for you but if people feel they do not want to do it, no problem !
A few months ago, I did a 40mi bike ride on day 10 of a 14 day fast. Last week I rode 78mi on day 5 of a fast and broke the fast 2 hrs after. Rode 100mi today after fasting overnight with only an exogenous ketone supplement to start and at 50mi. I love being fueled by fat…I can go all day (10 hrs today) while my carbage friends need to eat some carbs every hour or two.
Curious to hear more. I posted about this yesterday but didn’t get many replies. I train 4-6 hours a day and interested in trying longer fasts but afraid of drops in performance. Do you find exogenous ketones critical?