Does the 100g/hr advice hold for shorter events? I was watching a UCI XCO race and they seemed to be grabbing straight water each lap (taking a few gulps and dousing with the rest and then dropping the bottle). Then I’d see someone grabbing what appeared to be a gel of some kind from a rear pocket. No one looked eager to carry much up the hills.
None of my races have laps quite that short. I don’t get to go through a feed zone for water 6 times during the race. Maybe 2-3 times over 90 min.
I don’t know for sure how much, but I am certain that many XC racers are drinking carbs during XCO races..
As much as I can get down. Nature of an XCO course makes it hard, maybe 2 or 3 times on course where you can get a drink or take a gel, still can approach 90g/hr though (1 gel and one bottle per lap).
You really don’t need “fuel” for a 60-90 minute event. At the intensity they are riding it is doubtful the stomach would absorb much anyways. But there’s always the mental side of it and a gel or two might provide the comfort to keep pushing. (I remember a podcast where Chad was talking about how just a sugar rinse can trigger the brain positively, so there is that).
I also noticed riding taking drinks in the 20 min XCC. It was really hot so I get it… but you really can get through 20 min without it. That would be like in a 5k record attempt someone taking a drink every lap or two. Strange if you think about it and I was kinda curious about it as well.
Last season our cat2 XC MtB races were all about 90 mins. I always took one bottle only with around 100g of carbs and just used that. Never needed a hand up.
This year in Cat1 our races are 2hrs + and I definitely finish one bottle and about half of the other bottle that my wife hands me after lap 2 or 3.
The arguement that you can store 90 minutes of carbs therefore you don’t need exogenous carbs, is well debunked. Performance increases in the presence of large amounts of extra available fuel. That said, the why on this is still up for debate, and interestingly, some of f the science is suggesting that it might be psychological or about available brain glucose enabling someone to push harder rather than glucose availability at the muscle fibre.
That said, I don’t think rates over 100 will offer much more than something like 60. Very high carb fuelling rates are about getting ahead of the burn which is physiologically unsustainable in longer events.
Absolutely take in as much fuel as you can handle (YMMV). There are no downsides as long as your stomach can handle it. Which is the BIG caveat. So personally, this will take some experimenting on your end. However, as the heat/humidity/intensity goes up, generally the stomachs ability to digest and absorb carbs goes down. So these high carbs taken in road/gravel are not practical or even necessary.
XCO pro’s are definitely taking in carbs and I’m sure everyone is different on the amounts. In addition, pros take plain water for cooling and hydration.
I think cyclists are used to drinking more often since carrying bottles is so easy. Runners are used to not drinking, especially track runners. Having water available was unthinkable doing quarter mile repeats in high school. Maybe some ice chips if it was crazy hot, but my coach was old school.
Unpopular opinion, but I have seen no performance difference racing XC fueled vs water only. I do use mix though because it tastes good 
If you’re going to carry a bottle anyways, why not have salt and fuel in it? 1.5 to 2 hours with an NP 250ish watts is still a bunch of Kjs being burned. And unlike when you are coasting on a road bike, the non pedaling times i.e. descents on an mtb are still pretty calorically demanding.
As the temp climbs adding more salt to my fueling helps a ton with being able to keep the higher calorie intake going.
Last year I remember a racer telling me he could never keep on my wheel when I attacked in the last 20 minutes of a race. Fresh, he would walk me on a climb, but in the hour preceding my attack, I had taken in 3 bottles and 90ish grams of carbs. He had maybe gone through a bottle with maybe some calories in it. It isn’t about surviving, it is about being as fresh as possible late in the race and being able to make a move.
If I forget my mix, I’m not just going to turn around and go home.
I mean, I might go grab a bottle of mountan due to put in one of my bottles then. But yeah, point taken, There are like 3 things minimum required to race, a bike, shoes and helmet. If those things made it to the race, then it’s go time. I might could find a helmet to borrow, shoes are tougher and a bike, well yeah, I don’t think anyone is borrowing me a bike at the race.
I just finished a weekend of XCO racing. I carried a small bottle with about 90 grams of carbs both days. I was able to finish strong both days while the guys behind me seemed to fade. Maybe it was just training and fitness but I think that the carbs help. Yesterday was a lot hotter than Saturday so I also carried a bottle of water and used it to spray my legs and back.
Thanks. How many bottles total for the race? Just the two on a warm day?