Carrying fluid on race day

Last year was my first foray into long distance MTB. WIlmington whiteface 100k. My race day nutrition was an epic failure due to nerves and poor planning and I suffered for my mistakes. So this year I’m going back with a new game plan.

I sweat A LOT. I’m a 45y female, 130 lbs and on my trainer in a 60 degree garage I’ll lose close to 2 lbs an hour. I’ll come back from 2 hr MTB rides down 1-2 lbs taking in 32 oz on the ride. I’ve never done one of those sweat tests but there isn’t a lot of residue so I don’t know if I’m also a heavy salt sweater. Anyway… listening to the TR podcasts I hear Jon and Chad talk about 750mL - 1L per hour. Which seems lovely. But for a 6 hour race that’s 12 lbs of water. That’s close to 10% of my body weight to carry. Last year, because I was dying :joy:, I stopped at all 4 aid stations but this year I’d love not to… but I also don’t want to start the race carrying even 5-6 lbs of water. Do I have to? How do those of you who sweat like me handle this for long races? Thanks!

For a race of that distance, you’ll probably want to stop at at least 2 aid stations. A few years ago, I did PCP2P which is 77 miles of single track with 10k+ climbing and stopped twice. I had a 1.5L USWE pack and a 750ml bottle in the frame. If you did the same, you’d have 2.25L to start which gives you 2 hours and a bit at 1L/hr. You mentioned a 6-hour time, so that works. You don’t want to carry enough for 6 hours, but you don’t want to stop more than necessary.

Also, you didn’t mention it, but sodium is important to hydration. So, you don’t just want water but a hydration mix. I usually bring my own hydration packs on longer races and mix with water provided at aid stations as the hydration mix at races can vary greatly in terms of dilution.

As with everything, try it out before race day.


Lots of variables to consider on the hydration strategy. I don’t think drafting is important in that race, so that takes out a big one (it’s not critical you match what others are doing to stay with a group). At that point, it’s really a math problem of time required to stop vs. how much the extra weight it going to cost you. Weather is a big driver here. I’ll often plan to go lighter on fluids early and then ramp up consumption as it heats up. Sometimes that means sticking an empty bottle(with mix) in the back pocket and/or frame that can be filled to increase carrying capacity when it’s needed. Or start with a partial hydration pack. Very little weight penalty to have extra carrying capacity when it’s empty. You can play with best bike split to see how much an extra x pounds might slow you down vs. how long it would take you to stop. I seldom regret carrying extra, much more often kicking myself for not carrying more. I like to minimize stops and take the weight penalty. Stops are another place where things can go wrong and they can be slow at some events if you rolled into it when they are busy. I’m almost always doing hydration pack, bottle in the frame, and sometimes bottle(s) in back pockets. I typically bring my own mix in pre-measured baggies.


You’ll want to stop at some aid stations. I usually carry a 70oz hydration pack with Skratch, a bottle of plain water, and gels/gummies/bars.

Bare minimum, you want one and station with a drop bag (if allowed, most long races do) with extra food, extra drink mix, and some C02/tube/hanger.

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I’ll be back at WW100K this year. This is my first event of the year, I’m in MUCH better shape and on a much lighter bike than last year, but really treating it as a practice and training event.

There’s an aid station with drop bags allowed at the turn-around, you need to drop off bags the night before. I personally am probably going to be in the 5 hour ballpark, so depending on weather I’m going to try using that as my only stop. I’ll refill on water and use pre-mixed powder, and pick up my extra gels there.

I don’t think about water in weight, I convert it to Liters when I test because that’s what I’m taking in. I personally need roughly a Liter an hour at 60 degrees, cool and dry. So, I’m looking at needing roughly 2.5L per leg, maybe more. I’m going to carry a 2L USWE backpack, and a 1L bottle. If the weather’s hot, I may end up carrying a second bottle.

I also need roughly 1000 mg/L of sodium, maybe a little more. I don’t see residue either to be honest.

Fueling for me is 100-120 g/hour. I’m going for mostly liquid, 50/50 mix of fructose/malto powder. But will do the last 20 g/ hour via gels in case my stomach isn’t feeling it and I want to ratchet it back some.

For those that don’t know WW100K, lots of climbing too. Mixture of pavement, lots of dirt two-track, very little single track. They got rid of the crappy single track at the end because they’re not using whiteface this year.


Last year I was off the bike in practically full tetany on the blueberry trails… it was awful. I ate a handful of salt pills (probably at least 2g of sodium) and some food and LMNT (my electrolyte drink) and the cramping eased enough to get back on my bike. But I had to keep it in check the rest of the day. Any intensity and I could feel the muscle fasciculations start again. I’m hoping for under 6 hours this year. I just did a 70mile gravel with a little over 5k climbing and started with 1.5L LMNT in my USWE and an empty bottle on my frame. I stopped at one aid station and chugged a half bottle of water then made 20oz LMNT. I also use watered down maple for carbs so got 6 oz there. That took 4:40 and I felt good. I just dont want to climb styles brook carrying an extra 5 lbs :joy:

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If that was your experience - I’d make sure you’re taking in 1000 mg sodium (one full LMNT) per liter of water. You might want even more.

You could always go the route of the backpack on your back, but empty bottle on your frame with LMNT and carbs already in it that you could stop very briefly and top off with water at one of the intermediate aid stations on the way out and back. On the way out, I’m pretty sure that stop was at the top of Styles Brook Road before you make the turn up Jay Mountain Road about 1:10 in for me on a 6 hour pace. You might be able to get away with one bottle to that point, and an empty backpack with carbs and sodium powder already in it for that big climb up Styles Brook.

At the turn around, you could either have an extra bladder for your backpack and bottles already ready to go, or mix stuff up there. I’m forgetting where the aid stations were on the way back, Haven’t gone back to figure it out yet, but I think you could do a backpack back to the same aid station you stopped at on the way out at the top of styles brook and then top off there.

Do you find the USWE bladder hard to fill? I struggle with it and thus hadn’t even considered not having it filled for Styles Brook. I just checked the website and there is an aid station around mile 20 after the styles/jay mtn climb. That could be ~120min for me I think. I wonder the time savings for 3 fewer lbs on my back would be for that climb. And ordering an extra bladder for the drop bag. Good ideas! Thanks!

No issues filling from my perspective. You do have to take off the pack, take the bladder out, open it, fill it, reverse.

I seem to remember not seeing a second aid station outbound last year, only inbound. There was the one at the top of Styles Brook, and then I remember the turnaround aid station after the single track.

Try your race strategy during you long training events see what works and feels comfortable while MTBing…However, and it’s a big however as nice as it is to MTB XCM without a hydration pack it becomes very dicey trying to drink bottles whilst racing… as you get more experienced you will see what works…some have mentioned but try drinking a bottle of your goto fluid during the hour before you race, then at the aidstations you stop at down a bottle with your mix and top off the bottle…this tactic will slow you down so if your trying to podium it’s not the best strategy… and eventually you will have to pee…I also have the helpers help me I’ll give them a bottle and packet of mix and ask them to fill it for me as I fill the other bottle or take on solid food and tend to the hydropack…

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