Sunday, May 31, 2015

The Physiology of Endurance Cycling - Getting In Gear



In my role as director and guide rider for our cycling tours I'm often asked about how to gear up for our rides, most of which are relatively long, on consecutive days, and include a lot of climbing. In fact my preparatory correspondence with our riders includes clear recommendations on gear choice.

I recommend from the start that they should aim to get the lowest available gearing - ie a lowest combination of a 34-tooth chainring and a 28 or up to 32 largest sprocket on the back depending on their available range. This would be available within the range of the now-standard "compact" crankset configuration of 50/34, with the new Sram Wifli system also allowing the use of a cassette with up to a 32-tooth sprocket. While this is not going to be everybody's daily choice of gearing, for endurance rides it means we can spend more of the ride at a relatively high cadence, even on steeper gradients, which will mean that we can last longer without a significant build-up of muscle acidosis or fatigue. You can watch a recent GCN video if you need further convincing of the value of a compact when it comes to climbing.


However, I often find that though people will set themselves up with low gearing, they often don't really know how to make the most of their gear options, and many will still grind away on a higher gear, leaving  a cog or 2 "in reserve" for when they run out of strength, and I feel there are still a lot of similar myths out there on the biomechanics of riding a bike that are difficult to dispel. It's an old sport with a lot of baggage! This is my attempt to give a basic understanding of what your body goes through on longer rides and how to prepare for it with your equipment and training.

"COMPACT" GEARS

The term "compact" in cycling jargon currently refers to a smaller combination of chainrings on your crankset. The standard issue of chainrings for many years was a 53-tooth large ring, and a 39-tooth small ring. Now the most often-used compact setup is a combination of a 50 and a 34-tooth, though 52 with a 36 is another popular combination (often referred to as "pro compact"). Many people resist getting compact gearing through misplaced fears that moving to easier gearing will make them weaker riders through loss of power. There are a number of reasons why this is not true.




Firstly, we don't all necessarily generate maximum power by pushing a larger gear, and if you happen to be one of those who currently does, you would almost certainly increase both power and endurance by training your biomechanics to work at a higher cadence. Think of the image of Chris Froome on Ventoux in 2013, attacking with those repeated bursts of 120+rpm cadence that gave him a speed which nobody could match. You can laugh at his faith in the numbers, but he had trained specifically to pedal that fast, and knew not only that his power was highest at that cadence, but also that he would recover from that effort faster. I know myself from experience with power meters, that pushing a higher gear at a lower cadence, which feels instinctively like you're putting more power into the pedals, is often a gear or 2 higher (and a few rpm lower) than the one that actually registers the most power on the meter relative to the cost to your energy systems.

This however depends as I said on your own habits, physiology, training agendas and subsequent conditioning. If you're used to a slow cadence, then simply trying to spin faster will have the immediate effect of costing your energy system more. You will need to spend time developing the biomechanical adaptation to a higher cadence before you start to see the improved efficiency I'm referring to.


Secondly, unless you rely on entirely random opportunities to improve your cycling power, your choice of gearing will be based on the currently desired training effect. Just because you have an easier gear won't mean that you have to choose it. And if your body does tell you to back off, it's usually because it needs a rest, at which point it's very beneficial to your long-term development that you have the easier option and take it.

Thirdly, for those who worry about spinning out on a 50x11, if you train yourself to pedal at a higher cadence, you're going to get more speed out of a 50x11 than you got previously out of a 53x11, with better muscular endurance and less build-up of acid. You can refer to an earlier post where I touch a little more on the science of gearing.

There may be a good argument for having a couple of bikes with different gearing for different demands. I know Contador generally uses a 53/39 but changes for steeper terrain, and has been seen to change to a 50/34 for the climbs in the last week of the Giro or Vuelta. Obviously I'm not suggesting we mimic him. He, along with most top pros, has a power output that most of us amateurs will never get close to, and he weighs 62 kilos! I'm merely pointing out that even the worlds greatest climbers find a specific use for the easiest gearing. He's even been spotted with a 32 on the back. He makes sure he can always find his ideal cadence regardless of the terrain.

Contador using a Sram medium cage Wifli RD and 32-11 cassette.

ENDURANCE RIDING

Right, so it's clear that when we're training, we choose gearing according to the desired training effect, but that for endurance rides, a different set of considerations define our choices. What are they?

To answer this we will have to dissect an ideal approach to cycling technique over longer distances.

THREE CONSTANTS

My approach is that in endurance riding there are 3 constants that take precedence over all other considerations:

CADENCE > EFFORT > MOMENTUM

We don't need to obsess on exact rpm, bpm or kmh. It's more a question of a set of principles to keep in mind. Whether you like to use gadgets to monitor these constants for the rides themselves is up to you. Perceived information is perfectly adequate, and often better, than following a set of numbers. However, in order to train for this type of riding, we will need to know what is going on, so a measure and understanding of cadence, heart rate, and power output is of significant value.

CADENCE

As I've already pointed out, with a higher cadence we will resist fatigue longer. We should aim to develop an ideal cadence of above 90rpm. Some of us will find an optimum point above even 100rpm, but according to most of the research, for most of us it will be between 95-100rpm.

So we take our cadence as the primary constant. This means we will need to use our gearing to ensure that as much as possible whatever terrain we meet, we can stay close to our ideal cadence.

EFFORT

Our effort is the secondary constant. This can be measured by power, but for endurance purposes heart rate is perfectly adequate. For most of the ride we should be aiming to keep our effort at a pace we can sustain for the expected duration of the ride. This can be different for each rider as some of us have extended our ability to use our fat-burning aerobic system at higher intensities than others. If in doubt, for rides of expected duration of over around 5 hours, it's best to aim to keep your heart rate within zone 2, or low zone 3. That means we stay well below our lactate threshold as much as possible. As the ride gets longer, so the intensity goes down, It's better to be conservative.

MOMENTUM

Momentum, as the 3rd constant, is the first to be compromised in an endurance situation, but there are situations where we would choose to briefly compromise on the constancy of effort, to maintain momentum.


To illustrate what I mean we should look at a variety of terrain conditions.

ROLLING TERRAIN



This refers to terrain that is mostly maintaining the same altitude, but has recurring short rolling hills of anything from a few meters of road surface to 50 or so. Again it depends on the rider and situation. It would usually mean a surge in effort of no more than a few seconds. A peloton in full stride, or a solo Cancellara or Gilbert would probably consider a rise over a 100m stretch of road within this category, but even that may change after 300km in the saddle.

In this situation it will be better to maintain cadence and momentum at the temporary expense of effort, since we lose too much by constantly switching gear and slowing down to maintain a low heart rate. We should keep it to a point at which we can recover quickly between efforts so that our overall effort doesn't creep above our target zone.

So instead of switching gears all the time, we should select a gear that gives us enough resistance for a good spin on the flat, and push over each rise by getting out of the saddle. This of course increases our effort momentarily, but not enough to push our average out of our endurance zone. The added benefit of this is a regular change of position, which aids in resisting the onset of stiffness and cramps that can occur on long rides.

SEVERELY ROLLING TERRAIN

This is terrain that is repeatedly up and down, but with ascents that are too long to blast over without compromising the consistency of your effort, and usually with descents that allow you to get a bit of speed up.

The way you'd approach this for an endurance ride is to maintain quite a strict consistency of cadence and effort, which will mean quite an annoying amount of gear changing, but there's no way around it if we want to comfortably get to the end of the ride. As we hit the beginning of the ascent we shift down to the small chainring and then down the cassette as the gradient demands to maintain cadence and effort. We will lose quite a bit of momentum on the uphill to stay within our effort zone. As you crest the hill, keep the force on the pedals constant and shift up as you go over, shifting to the big chainring as soon as you pick up enough speed to do so while maintaining cadence. If you continue the work rate on the downhill you will pick up enough speed to retain some momentum into the start of the next ascent.

LONG HILLS


When we're looking at an hour or more of continuous climbing, we should aim to maintain cadence as much as possible, thus momentum is the first constant that we drop. As the gradient creeps up, or the length of the climb starts to take it's toll, our effort will start to push out of our desired zone. At this point, we will have to make a decision based on the remaining agenda. If we still have a long ride ahead of us, we will have no choice but to compromise on cadence in order to keep our effort within our endurance zone. If however, we are about to finish, or even just stop for a break, we might choose to maintain a good cadence and push our effort up towards our threshold. To illustrate I'll give an idea of an endurance approach to a 15km climb I often do. This would be my approach if the ride were over 150km or so.

At the start of the climb proper I'll probably work quickly down to a low combination as the road hits an average gradient of 5% for the first km or so, as I stay at my preferred cadence of around 95-100rpm and in my target effort zone. Then the road flattens out a little, and varies between 2-4% for most of the next 3km so I'll shift up a gear or 2, maintaining cadence/effort. Then there is a kick at 8% of around 200-300m before a flatter section, at which point I will probably be down to my lowest 34x28 but to maintain effort I'll allow for a drop in cadence. Once on the flatter section I'll shift up to maintain cadence until the road kicks up again, at which point I shift down and continue to maintain cadence and effort. The second half of the 15km climb is tougher, with more sections between 5-6% and some kicks up to 8-9%, so my cadence will creep down accordingly in order to keep my effort constant. Though in training on this same hill I would often use bigger gears, in this endurance situation I will probably be on my smallest compact combination for around half of the climb.


SHORT, SHARP HILLS


Think Flandrian "bergs" here. These are hills that are steeper than we can comfortably spin up even in our lowest gear. Say we have a ramp of anything from a few hundred meters to 1.5km at an average gradient above 15%. Most of us will be in extreme discomfort if we try to maintain an endurance effort, as we will be compromising too much on cadence even with the lowest gearing, so we will need to allow our effort to rise considerably while keeping a cadence and momentum that is sustainable. Once we're over the crest we'll need to ride easy until we recover and our heart rate comes back down to the lower end of our zone. We will benefit greatly on these climbs by being able to comfortably ride out of the saddle for longer durations, spreading the effort to full-body muscular power, and giving our body a chance to change position. Of course we need to train specifically for this if we want to be good at it. Check my post on standing form drills for ideas for training this skill.

The ability to confront this sort of terrain repeatedly over extended periods requires a superior ability to recover from anaerobic efforts of 1-5 minutes. However, it should be obvious that the lower the gearing, the easier we make the task, and the more likely we are to survive to the finish. Again, we have to maximize cadence during the climbs, and also return to our ideal fast cadence whenever we get a chance to recover. Though Fabian Cancellara is possibly one of the most decorated time-trialists in history, his preference for a high cadence is key to his latter-day ability to also dominate the spring classics of Flanders.


So hopefully this gives a basic introduction to the principles of endurance riding and the preparation needed, both physiologically, mentally, and mechanically. As always this is based on my own personal experience, and is part of a work in progress. There are surely many other ways to think about this, and I'm keen to hear how others have approached the same challenges with success. I keenly await points of discussion or ideas that add to or challenge the concepts I present here.



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