The Positives Of A Negative Bike Split

Negative-splitting endurance events has been a smart and successful approach to racing for ages. This approach, in which you race the second half of your bike leg faster than the first, sounds easy, but it can be deceptively hard. There’s an art to doing it correctly.

Why should you try to negative-split on the bike? Simply put, the bike is the portion of the race that takes the longest, and therefore requires a sound strategy. The benefits are many, and some don’t reveal themselves until well after T2. Below are some of the tips Coach Carla Weier and I give to our athletes in the LA Tri Club Performance squad.

What is a negative split strategy?

A negative split is when an athlete gives an easier effort at the beginning of an event and a stronger effort towards the end. The expectation is that by holding back and going easy from the start, you are guaranteed to have more energy, a faster speed later in the race, and better overall times. When the opposite approach to pacing is applied, there is too great a risk that a few, fast, early miles will turn into a slog soon after. That will result in a far worse time for not only the bike split, but for the overall triathlon.

Below are some hard numbers as an example using speed and time. The bike leg of a non-drafting triathlon is nothing more than a time trial, so speed and time are used to tell the hard, final truth.

The value of negative splitting the bike leg is far more obvious in the longer events so let’s break down the iron-distance. Here’s a common, logically-balanced 13 hour Ironman:

RELATED: 5 Ways to Blow it on the Bike

A tale of two races

If the athlete in the Ironman above rides out of T1 feeling good, and rides hard at 20 mile per hour average for the first half of the race, they get 56 miles covered in just 2 hours and 50 minutes. That’s a nice start. But now, halfway through the bike, things get tougher. Lactic acid from that hard effort doesn’t get flushed out as easily, and starts to build up. Later in the day, the heat comes on. It’s harder to keep up with hydration and calorie needs. All those factors and possibly more (hills, wind, mental fatigue, etc.) combine to slow the athlete down to a 13 mile per hour average. Because of these factors, the second half of the bike takes 4 hours and 20 minutes. The total bike time now is 7:10 – ten minutes slower than a 16 miles per hour average listed above.

Now let’s apply a negative split. Say the rider starts out very easy, at 14 miles per hour for the first third of the bike (2:37min), then picks it up to a moderate pace of 16 miles per hour for the second third of the bike (2:17), and then finishes the final third of the bike comfortably strong at 19mph (1:56) for a total bike time of 6:50 – ten minutes faster than the 16 miles per hour average initially listed.

What’s demonstrated here is a 20-minute sway in bike times from a pacing strategy that might be described as “Out Strong, Blow Up, Crawl In” of 7:10, to a negative split of “Easy, Moderate, Comfortably Strong” of 6:50.

Why it’s so hard to pull off a negative bike split

This looks so good here in the written word, but can be difficult for some athletes to execute for some basic reasons.

• One, it’s a race! Shouldn’t this feel like racing? 14 miles per hour for someone who can ride 19 miles per hour is antithetical to “racing”.
• Two: Aren’t we supposed to pass people in a race? Certainly, riding at 14 miles per hour is going to result in a lot of people passing you. Those counterintuitive, ego-driven perspectives have to be controlled, and one must trust the delayed gratification of re-passing those athletes who blew by you at the start of the bike.

The biggest benefit of your negative bike split

Here comes the double benefit: the run! Going out strong on the bike and struggling into T2 is slower for the bike, yes, but then the run becomes a real problem. Athletes who blow up on the bike begin the run in a hole: stiff, slow, and flirting with cramping. That tough run can quickly become a walk. Covering big chunks of a marathon at a jog vs. a walk is a difference of 3+ hours.

This mathematical breakdown above can be performed for any race, whether it’s a 70.3, Olympic, or sprint. The shorter the race gets the thinner you’ll want to slice the negative split. For a 20k bike, the pace of the first half might only be slightly easier than the pace of the second to achieve the desired result.

Speed isn’t the only factor

As stated earlier, speed cannot be what drives your pace. Average bike speed is impossible to control during a race because of wind and hills.

Heart rate

Using heart rate has some problems, too: the biggest is the slow reaction time to heart rate. As an example, say you want to average 140 beats per minute for the first half of the ride and 152 for the latter half. At the base of a short, steep climb you roll into it at 138 beats and think, “I’ll get out the saddle and just attack over this bump”. Midway up, you’re at 139. At the top you’re at 141. Now you start down the other side, but you see 148; half way down you read 156. Near the bottom you’re just coasting trying to get it under control, but the heart rate is still reacting to the effort you gave to attack over that hill and it’s now reading 167.

Another issue, especially in longer races, is a phenomenon called cardiac drift. As dehydration creeps in and fatigue builds the heart beats faster to do the same work, and you might find yourself going very slowly to stay on target.

RELATED: How to Use Heart Rate Training Zones for Triathlon

Power

Power can be a good governor on the bike. It’s far quicker to react to a hard or easy effort than heart rate. To make the most of pacing from power, set your screen to view both 3 second average power (the most immediate) and normalized power for the entire ride. An athlete can go into a race with a successful pacing strategy based on testing and training. It might have three values like:

• Never exceed 300 watts.
• 280-290 watts can be held for 15 seconds 15 times but no more.
• Aim for normalize power of 180 watts for the ride.

RELATED: Riding with a Power Meter Will Supercharge Your Training

RPE

No matter what method you choose, you should always have Rate of Perceived Effort (RPE) in your mind during the whole race. To utilize this at the beginning of the bike, ask yourself “Am I riding easily enough to pick it up for the second half and still have a good run off of this ride?”

Later in the bike ask yourself, “Is this pace too hard to run well off the bike?”. This kind of assessment can account for anything and everything that might be affecting you in that moment: humidity, quality of previous night’s sleep, emotional stress of the recent past (everything from traveling with family the days prior to witnessing intentional littering 40 seconds ago), and more.

To put a good negative split to use on race day, apply it to several brick workouts in the weeks leading up to your event. Combine an objective system (HR, Watts) with your subjective system (RPE) and begin to learn exactly what performance capabilities you have. Then, on race day, stay open to the oddities that can spring up: heat index, mis-measured long swim, dropped bottle, etc. etc. and make adjustments as needed.

RELATED: Executing Your Race Strategy: The Bike

Ian Murray is a USAT Elite Coach and the Head Coach of the LA Tri Club’s PERFORMANCE Team.