Your first century: 100 miles, and how to arrive with legs left

A hundred miles is 161 km, and for most riders it is the first distance where the last hour cannot be got through on stubbornness alone. Riders who finish well have done three things: built their long rides up to around 120 km beforehand, ridden the first two hours slower than felt necessary, and eaten from the first hour rather than from the first hunger pang. Riders who finish badly have usually done the opposite of one of them. The rest of this post is about those three, plus the day itself.

How long the build needs to be

The single best predictor of a comfortable century is the length of your longest ride in the month before. You do not need to have ridden 160 km in training; you do need to have ridden something like 120 km, because the last 40 km are where the day is decided and they are much less frightening if you have already been out for five hours once. Our rule of thumb, and it is ours rather than a study's, is that the longest training ride should reach about three-quarters of the target distance two to three weeks before the day.

The reason to build gradually rather than jump is not only fitness. Gabbett's work on training load and injury shows that sharp week-to-week spikes in load are what produce injury and illness, while a steadily rising load makes athletes more robust, not less. A long-ride progression of roughly 60, 75, 90, 105, 120 km over six weekends, with a shorter weekend in the middle if you feel wrecked, is the sort of curve that stays on the right side of that. If you are starting from further back, zero to your first 100 km is the post to read first.

• Ride the long ones at conversation pace. The point is time on the bike, not average speed. Save the intensity for a midweek session.
• Practise the eating. Every long ride is a rehearsal for how you will fuel the century. Use the same food, the same bottles, the same timing.
• Practise the position. Numb hands, a sore neck and saddle trouble all get worse with hours. If they appear at 90 km in training, fix them before the day. Our post on what to pack for 100 km covers the kit; add spare food and a second tube for the extra distance.

The Moveee plan wizard takes an event date and a long-ride day and lays this progression out for you; set the goal as a race and the long-ride distance will step up towards the date.

Why the last hour is different

Maunder and colleagues made the case that endurance riders should be profiled by "durability": how much their power, efficiency and threshold decline after hours of work, rather than only what they can do fresh. The practical version for a first century is that the rider you are at hour five is a weaker rider than the one who started, and a pace that felt sustainable at hour one will not be by hour four. Long rides train this, which is why the build matters more than any interval session. Our post on durability and hour-four power goes deeper.

Pacing: slower than you think, then hold it

Abbiss and Laursen's review of pacing strategies concludes that for prolonged events an even pace is the most efficient, and that a fast start followed by a fade, the "positive" pacing most novices produce by accident, costs time overall as well as making the end miserable. The century is the archetypal event where this applies, because the first hour on fresh legs, in a group, with a tailwind, feels absurdly easy. It is not free.

• With a power meter. Aim to hold the first three hours at or below the top of your endurance zone, roughly 55 to 70% of FTP, and accept that the fourth and fifth hours will drift down from there whatever you do. If you have a Power Profile in Moveee, use the FTP there rather than a hopeful number. Our post on gran fondo pacing with power applies the same logic to a timed event.
• With heart rate. Keep the first half in the zone you use for long easy rides. Heart rate drifts up over hours in the heat and with dehydration, so the second half is best ridden on feel.
• With neither. You should be able to speak in full sentences for the first four hours. If you cannot, you are going too hard, whatever the group is doing.
• Climbs. Sit down, drop a gear more than you want to, and let the fast people go. Every climb ridden at threshold in the first half is borrowed from the last 30 km at a punitive interest rate.

Drafting: the biggest free saving there is

McCole's measurements of energy expenditure while cycling found that riding directly behind one rider at 32 km/h cut oxygen consumption by about 18%, and that sitting in a group of riders at 40 km/h cut it by around 39%. Nothing else in this post saves anything close to that. If you are riding an organised event, find a group going at your pace and sit in; if you are riding with friends, take shorter turns on the front than they do and be honest that you are the one for whom the distance is new. The rule that goes with it: never let the wheel in front pull you above the pace you decided on. A fast group is a slow finish.

Fuelling: from the first hour, by the hour

Jeukendrup's guideline for rides over two and a half hours is 60 to 90 g of carbohydrate an hour, with the higher figure needing a mix of glucose and fructose. The ACSM/AND/DC position stand gives the same range for exercise beyond two and a half hours. A century at 25 km/h is six and a half hours, so the total is somewhere between 350 and 500 g of carbohydrate on the bike, on top of a proper breakfast. Riders who bonk at 130 km have almost always eaten well under this, usually because they felt fine and did not start until hour two.

1. Breakfast, three hours before. 1 to 4 g of carbohydrate per kilo in the one to four hours before, per the position stand. Porridge, toast and jam, a banana, a juice: something you have eaten before long training rides.
2. Hour one. Start eating at 30 to 45 minutes, not when hungry. A rice cake or half a bar.
3. Every hour after. 60 g: two pocket items or one item plus a bottle of drink mix. Set an alarm on the head unit if you forget.
4. The café stop, if there is one. Carbohydrate and coffee, nothing fatty, twenty minutes. See coffee-stop nutrition.
5. The last 90 minutes. Switch to gels or drink; solids sit worse once you are tired and the pace lifts for the finish.

Our post on carbs per hour covers the targets, and home-made rice cakes, bars and gels how to make the food without spending a fortune.

Drinking

The ACSM position stand on fluid replacement aims to keep body-mass loss under about 2%, which for most riders on a mild day is one bottle an hour and on a hot day nearer two, with sodium in them for anything this long. Kenefick's review sets out when a planned drinking schedule beats drinking to thirst: essentially, the longer and hotter the event and the faster you are going, the more a plan helps. A first century in summer is a case for a plan. Know where the taps are on the route; a 160 km loop with one refill is not a route, it is a problem.

The week before and the day itself

• Taper lightly. The last long ride should be two weekends out; the final week is easy riding with a couple of short efforts to stay sharp. See the taper.
• Eat carbohydrate for two days. Not a heroic load, just bigger portions of the usual, and less fibre the night before.
• Check the bike the day before, not the morning. Tyres, brakes, chain, and a spare tube you have actually checked fits.
• Plan the route in segments. Four blocks of 40 km with a known stop in each is much easier to hold in your head than 161 km. If you build the route yourself, the Route Builder profile shows where the climbing sits so you can put the stops before it rather than after.
• Start early. Cooler, quieter roads, and a margin if something goes wrong.
• Expect a bad patch. Somewhere between 100 and 130 km most first-timers have half an hour where it all seems like a mistake. Eat, drink, drop the pace slightly, and it passes. It nearly always passes.

The finish will feel like an achievement because it is one. The version that feels good, rather than merely survivable, is the one where the training was long enough, the first hour was slow enough and the pockets were full enough. None of that is difficult. It is just easy to skip.