Over 60g of carbs per hour but still bonked

38yr M, FTP 247, 67kg

Yesterday I ride 220km. A short commute to the start of a 200km Audax, and short return.

The Audax time was 10hours of cycling, with about an 75 minutes of breaks. During the ride I was consuming 60g of carbs quite happily. Stopped for lunch and had a sausage sandwich and fries. The first 150km was all good, felt good and was ticking along at a decent speed and power. Not completely sure if power numbers, because I tracked the commute as well, but at 150km my NP was about 150w. I was aiming for about 160.

After 150km we had a fairly string headwind for most of the remaining 50km and the hardest hills of the day. During this time I find that cycling on the flat I could happily hold 160w but when we hit the hills I struggled to get any power out. I tried to get 180-200 but often had to drop back to 140 to conserve energy for the steeper bits. At about 160km I had to stop because I felt dizzy. I had.some sweets and crammed as much food into me as I could.

I’m wondering, if my carb plan was okay and I still felt horrible breast the end - what did I do wrong? I’m wondering if I had enough carbs but not enough calories. I fuelled on hydration mix, gels and some dried fruit crackers + lunch. What could I eat differently for rides like this?

Just looking for advice to help with future events like this. I have a 213km ride in a few months with nearly twice as much climbing, and now worried I won’t manage it.

That’s what jumps out to me. It’s similar to the mistake people often make on our London - Brighton - London ride, and the advice has become ‘never have the fish and chips at the seaside’!

If you put a load of fat in you effectively block digestion for about 2-3 hours and slow to a crawl.

It could also be that you just went out too hard and the challenging part was where others, seeing the end in sight, also ramped up their efforts.

Alternative second mistake I’ve made that gives similar symptoms - not taking in enough salt.

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Yeah I was thinking the sausage. The chips were great :joy:

I think everything fine the last 50km difficult and I actually made up time on most people surfing that time, despite getting awful.

Salt should have been fine. Hydration mix has 0.8g of salt per serving and I had 8 servings. It also has electrolytes mix in it as well. It’s from bulk, from what it has in it it feels like it should be a pretty good mix of nearly everything needed.

Appreciate the reply. The sausage may well have been a big factor. I was conscious of not eating too much fat, but thought that would be fine.

What training did you do over last 4 months to prepare? Average hours per week? Longest ride?

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+1

this isn’t a nutrition problem

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TBH it hasn’t been as consistent as I would have hoped. I cycled the week leading into it but nothing the previous week due to illness. I was out for most of February as well, with illness, but managed to get out on a 2.5 hour ride each weekend in February. Before that, Dec and Jan were around 4-5 hours a week. My longest ride this calendar year before this weekend was about 60km… So as I’m writing this I’m understanding your point.

It may well be a conditions thing. I did feel great at 150km, not fresh but perfectly fine. Shortly after I just fell off a cliff and struggled. I know yesterday was a huge day.
I’m currently following a LV plan, only 2.5 hours total, topped up with a long ride on Fridays - typically 3 hours with a 6-8 hour ride once a month.

Ultimately it was a push but a worthwhile one. I’m trying to learn from mistakes and if one of those is consistency of training I take that onboard as well.

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I will muddy the waters further here by saying that sometimes you just don’t have it. I would not read too much into one effort. Sometimes you feel well and do everything right, and maybe the issues that have been brought up are not important, and you can just have a bad day, that’s cycling.

You need more data points.

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That was my first thought…sounds like a fitness issue, not a fueling issue.

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The nutrition could have been better (more carbs per hour and reduce the fat/protein at the stop), but this sounds like you came up short on endurance fitness. In particular, struggling on the hills late would be common as your legs struggle to do that work at lower RPM’s and less momentum while climbing. Getting back to those longer 6+ hour training rides should help.

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Just another vote for not having the long ride experience in your legs. Carbs help, but in the end, it’s just really hard to do long rides when you haven’t been doing long rides, no matter the pace or fueling.

First of all don’t beat yourself up. Even amongst experienced audaxers we don’t always get it right.

You really wanted longer outings in your legs before your first 200 of this calendar year. I would look to see if there is a series of 100km Audaxes you could do through the winter to keep the endurance ticking over.

Nothing wrong with sausage and chips during an audax. Hell I’ve had fish and chips, a curry, and Chinese and full English breakfasts during 400km events. But something I do do, is allow some time for it to digest. I don’t jump straight back on the bike immediately after eating such meals, nor when I do, do I resume pedalling at the intensity I was at coming into the control. Soft pedal it a bit whilst you digest your food.

75 mins is reasonable stop time, but given your ride time you had quite a bit of additional stopped time available to you and still be within the time limits. Don’t be afraid to have to have longer stops as short stops can be a false economy.

Well done on finishing and good luck for your next one.

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“I’m wondering, if my carb plan was okay and I still felt horrible breast the end - what did I do wrong?”

You’ve got about 1200 to 1500 kcal glycogen in your various muscles and liver. You were burning 400 kcal/hr or about. You were taking down 240 kcal/hr…so 160 kcal/hr deficit. After about 10 hours of that you’ll start to have issues. Is that when you started to ‘bonk’? About 10 hours in?

So I don’t think you did anything wrong except put a nutrition plan in place that was designed for a 10 hour ride. If you want to do a similar ride in the future and not bonk you need to take down more carbs/hour. If I were your coach I would not have let you attempt this event unless I knew you could take down 90g of carbs/hour comfortably for at least a 4 or 5 hour ride.

And, lastly, @Back2Basics I’ve looked at dozens and dozens of power curves from 12hr to 24hr events. It’s very, very typical to see power (regardless of the rider) settle into that 120W to 140W area for the last 25% to 30% of such a ride. It’s not just you. But if you keep forcing yourself to diligently eat during the FIRST 25% OF THE RIDE, it will not be you.

I think it’s been said but…

So at 150w np, you’re doing well into zone 2 or solid endurance pace. But if you haven’t done regular rides that are even half the distance of the event distance, your zone 2/“endurance” pace will be zone 2 for rides of perhaps a little bit more than what you regularly ride. You were just going too hard from the gun.

Carbs and decent nutrition won’t make up for not having done the time or the distance in training.

And the sausage sandwich and fries… Probably just what you needed. I had one of my best laps of a 12 hour MTB race after a bacon sandwich. It’s the morale boost of proper food, a bit of salt, fat and all the stuff you just sometimes need. It wasn’t what made the later stages of the ride a slog!

There might have been nutrition issues contributing to the “bonk”, if it was a true bonk. But it’s pretty much impossible to know how much glycogen he was burning through per hour based on info given. Sure, we can estimate a calorie deficit, but glycogen is only part of that picture. You can run on a calorie deficit for 10+ hours and hundreds of miles as long as you are running primarily off fat and not pulling too much from glycogen stores. Almost any ride done at a deliberate pace will make it impossible to eat as much as you are burning, so we are always going to be in a deficit during the ride. Tracking calories burned on the bike and then trying to match that (while on the bike or even after) is a flawed exercise since glycogen is the main part that needs to be replenished, but is only a portion of the calories burned. This is particularly true if you are trying to improve body composition, you ideally want to keep your glycogen topped off, but not replace all the fat burned.

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This is the type of thinking I like all my opponents to have! ;-D

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I’m surprised we got this far without talking about off-the-bike nutrition or asking whether the OP carb-loaded over the preceding 2 or 3 days.

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Nobody is taking in as many calories as they burn on hard training rides and races, not at the amateur level and certainly not at the pro level. There can be a healthy debate on the benefits of replacing all calories after a ride if trying to maintain body weight, but during a ride is impossible and not needed to fuel the ride (since a large portion if fueled by fat). On the bike, we should all be taking in as many carbs as we can and 100+g is a good target. Even at the 150g/hr some pros can do, they are still in a big deficit per hour vs. calories burned.

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@Back2Basics I just wanted to add one thing to help you understand what’s going on…because you might be thinking, ‘What about the bolus?’ A couple myths that were endemic when I was competing at ultra riding were that you couldn’t do long rides without having ‘regular’ food and that you could just ride at a moderate pace, stay hydrated, and stop every few hours for a bolus of calories & still perform.

The problem with the bolus approach is pretty simple (just like the calorie deficit/stored glycogen equation)…glucose/fructose absorption is rate limited by things other than mere consumption. If you can take down 70g/hr carbohydrate by incremental consumption of on-the-bike nutrition, guess how many g/hr carbohydrate you can take down with a bolus meal? Answer: 70g/hr. Actually, it’s worse than that and you can prove it to yourself with a quick literature search of blood sugar response to glucose bolus vs mixed macro bolus.

So, for you, the important thing is to train your gut to handle more carbohydrate/hr. For sure, you can get to 90g/hour with a little bit of training. Then, during the first part of the ride make absolutely certain you are taking down that amount on a regular schedule. That’s gonna get you through a 12hr-13hr ride in much better shape provided that you stay on a steady pacing program during the first part of your ride.

Good luck!

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After reading some of your posts I honestly don’t know how to explain a pile of my 6-16 hour performances that were fueled closer to 60g/hr versus 80g/hr.

This was 50-60g/hr Gu Roctane no other food during the ride.

4000kJ, 189W average power, and .81 IF.

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I don’t know now. Everyone said how hard it was after 150km. This was a combination of the terrain and headwind.

My friend I was with is a far better rider than me. He’s done several 100 mile rides this year and he is struggling today. He said that yesterday was far hard than another 200+km ride he did with double the climbing.

So I just don’t know if yesterday was a far tougher day than we had expected.