QUESTION: In a few months I will ride my first 300K (186-mile) brevet. A friend told me that the rule for pacing long rides is: Never go anaerobic. Sounds like smart advice, but how can I tell when I’m in danger of doing it? – Bud S.
RBR REPLIES: You’re talking about the “anaerobic threshold,” a phrase used for many years. Nowadays, the more common term is lactate threshold (LT).
To simplify the physiology, as you increase intensity, your body produces lactate. At relatively low workloads, the lactate is cleared readily. But at higher intensities, it builds up and you slow down rather dramatically.
The term “lactate threshold” refers to the intensity at which your body can no longer clear the lactate accumulation. Fit cyclists can sustain a threshold heart rate (about 90% of their maximum) for an hour. On longer rides, like your 300K, you’ll need to reduce your average heart rate considerably below that figure to last the distance.
You don’t need a heart monitor to do it. The trick is to ride at a pace that keeps your breathing regular. When breathing becomes forced it’s a sure sign you’re asking your system to clear a lot of excess lactate. Doing so uses muscle fuel and almost certainly means you’ll ride slower later in the event.
The trick is to keep your enthusiasm under control, especially on climbs or in pacelines where you might be forced to ride too hard.
That said, you can gain quite a bit of time on hills if you carefully elevate the pace to just below your LT and recover on the descents. But in a long event, you need to be extremely careful with this strategy because a foray or two over LT can cost you dearly.
Bottom line: If you’re breathing hard during a long ride, you’re probably in trouble – unless you’re so fit that extended efforts near your LT are possible. But riding that hard usually exacts a high price later in the event.
The only way to learn your maximum safe pace is to get experience in longer events. This is one of the educational benefits of a brevet series. With progressive distances of 200, 300, 400 and 600K, riders learn plenty about pacing and endurance.
Lots of us know what it’s like to push too hard early in a century or double century, then pay the price. But that’s actually an effective way to learn for sure where the limit is.
Forty years ago, I did the qualifiers for P-B-P here in the States. At that time I could ride a sub-five century on a reasonably flat course (about 2000′ elevation). This was basically a TT ride, but there was some drafting. When I did the 600 Km brevet, my elapsed time was 27 1/2 hours. I would have failed the 1200 Km riding in this manner. I had to have someone unclip my feet (and this was in the days of toe-clips) and catch me when I finished. I could not dismount on my own.
A company called Xert has software that can be run on an Android, Apple and some Garmins that will give you a good estimate of the calories being burned by fat and carbs. If you stay below your LT, these will be approximately equal. This requires a power meter and HR monitor. You can ride almost forever at this pace. In my late 70’s now, but using the principle’s you described, and monitoring my power output, I recently did STP in 12 hours.
My experience is that anytime you go over your Lactic Threshold, you are burning matches. And when you burn the last one, you have to stop and recover. And in my experiment of one, my current lactic threshold is about 148 watts. If I keep my peak power output below 220 (and the 220 is for a brief period of time, say less than 2 minutes) and my average power between 138 and 142 watts, I can do a Century ride with 8000′ of climbing in just over 7 hours, and I clock in a approximately 200 lbs.
While this might work for you, one way to determine how fast to ride when pacing the group is to never ride at a faster speed/pace than when you were riding further back in the group. In fact, you might need to ride at a slightly slower pace than when further back in the group if you were breathing heavily when further back in the group (or take a very short turn when pacing the group..
A good step in preparing for a 300 km brevet, is a garmin sport watch , like the fr165, 200$, and learn how to use it. Then read an article about how to perform a field test to determine your lactate threshold’s (very simple to perform).
Assign in your watch an alarm to the upper limit of your heart rate (hr) that suits your recommended hr for this brevet.
I also add a repeating 30 minutes alarm ,which remind me to eat/drink . It’s quite easy to forget and miss feeding on time .
The advantage of riding with a watch is that you know exactly when to slow down so you won’t get burned. It’s very easy, especially at the beginning when you’re fresh, to get excited and follow a faster group and lose control.
I use a heart rate monitor strap, which allows me to tie the watch on the handlebars, so I can always see the watch and the data.
Good luck
As a follow-up to the post back in 2022, the importance of nutrition and recovery when doing long events has become more prominent. We did Ultra-cycling Marathons in the 80’s. Once you get the power expenditure part of long distance racing (or riding), nutrition and hydration on the bike becomes a very critical factor in sustaining energy after about 3 or 4 hours.
At this point, you have burned most of your stored carbs by that time and if you have not replenished them, your blood sugar will start to drop. You can put a band-aid on it when that happens by ingesting carbs. But for a truly lengthy, six, seven or more hour events, you are playing defense at this point.
A clue for me that this is happening is that I become thirsty, but taking on hydration does not quench my thirst. If I don’t do something drastic (slow down, drink a Coca-cola with about 40 grams of carbs and caffeine) I’m headed for bonk territory. The coke is good for about 45 to 60 minutes for me.
Not everybody reacts to nutrition on the bike the same way. Take in too many carbs too early and too quickly and you run the risk of digestive issues, not enough, you run out of fuel and bonk. Most amateur level riders can burn more carbs than their body can absorb on an hourly basis. For true endurance, you need to find the limit your body can digest carbs, understand how you are burning carbs during the event, and make certain you understand when you are going to hit zero carbs. You will be able to continue beyond this point, but at reduced capacity and limited by how many grams of carbs your body can absorb per hour. A general rule for most healthy adult males is a carb reserve of between 300 and 400 grams when rested before an event. Keep the equation Carbs available = Starting reserve + ingested carbs per hour – burned carbs per hour greater than zero.
If you can master this, you can ride all day and come back tomorrow.
Find a source of nutrition your body is happy with while riding and determine your tolerance level for it. Start eating in the first hour of the event, maintain hydration, again starting in the first hour, and don’t forget electrolytes.