How To: An Introduction to the Pace Clock for Beginner & Improving Swimmers

Following my review of Brilliant Swim’s PaceWatch, it seemed an appropriate time to do an introduction to the Pace Clock commonly seen in most pools. Along with my guide to the different types and uses of swimming googles and the perennially popular understanding lane swimming etiquette, these articles are intended (mostly) for newer and developing swimmers. While is about open water swimming, I consider both learning the basics in a pool and continued pool training an essential component for almost all open water swimmers.

The pace clock, often called a lap clock, is an item that often causes confusion and even apprehension to beginning and some experienced lap and fitness swimmers. This nervousness means that many avoid learning its use, seeing it as tool for purely fast or advanced or competitive swimmers.

The pace clock is actually the single most useful tool for swimmers to improve, and ahead of all paddles, kick-boards and other toys so often used. Yet many swimmers who have never swam in a club environment never take the short time to understand its basic utility.

A swimming analogu pace clock, with the single hand almost pointing to 60 at the top.

Go on the red top!

The pace clock does not have an hour hand. Most do not even have minute hands, simply a single double-sided second hand, with one orange or red tip, that can be seen from the far side of the pool.

The pace clock has two primary functions.

  • Rest Intervals

The simplest use of the pace clock is to time rest breaks, often called rest intervals, between swims (often abbreviated to R.I or RI on swimming workouts). Swimmers new to regular swimming workouts, especially those who like me swim by themselves or don’t have a club background, will usually fall foul of the same basic mistakes. They struggle with technique, especially breathing, and instead of concentrating on getting this right first, will try to force themselves to do too many lengths. Carbon dioxide buildup forces them, sooner rather than later, to stop for air. The resulting break is usually too long. Another common problem is that of the more experienced fitness swimmer who simply swims up and down at a single pace, with no stops.

While always working on technique is vitally important, the fundamental structure of most swim training is interval based. Almost all swims should be broken up into repeats of varying distances, even if your target is your first “long swim” or triathlon.

So the pace clock is most commonly used to measure and control the rest intervals between swims. Using the old engineer’s maxim of “anything that is measured improves“, once you start to measure your intervals, you will start to control them. Instead of two-minute long rests while hanging off the wall, you will take one minute breaks (still too long) then 45 seconds, then 30, then down to 20 and 10 seconds. Your breathing control will improve. Your heart rate will decrease and your fitness will improve.

“10 x 100” is a very common swimming set for swimmers of most abilities, and all distances and speeds. It means to swim 100 metres continuously ten times, with a fixed rest interval between them.

For most swimmers that interval will or should be between 5 and 20 seconds. (Excluding maximum speed sprints for more advanced swimmers). You can take a longer 30 second rest before the start of your next set.

The same applies to beginners swimming single lengths. You should still control your rest time. Swim a length, rest no more than 30 seconds.

Pace clock use should become second nature to all swimmers looking to improve fitness, technique, distance or time, or all of the above.

  • Establishing and Controlling Pace 

animated_Seven_segment_display Clock timer

Once you have learned to control your rests, and your fitness increases, you will be better able to swim at a steadier speed. Controlling pace, the ability to swim at a certain speed for a certain distance or time, takes a longer time to master, and the first step is to know what it your pace actually is. You do this in the same way that you improve it: By swimming repeat distances on a fixed time to see if you can “make the interval“, i.e. hit the target time, consistently and repeatedly.

Those who have spent time in a cycling peloton will know the cry of “up, up, up” which signifies a sudden breakaway attempt. Similarly any swimmer who has spent time in a club or coached environment will know the phrase “on the red top” ( or “on the red bottom“, or “on the red 10” etc). These variant phrases mean that you start the first swim of the set when the red tip of the second hand reaches 12. Along with this will be the pre-determined pace interval. For example “on the red top on 1:40” means swimming 100 (metres/okay yards if you insist) in every one minute and forty seconds. The first time the red tip will be on 12, the next time it will be on 40, the time after on 20, the time after again it will be back to 12. (For this interval the hand will simply cycle through 12, 40, 20 and repeat, see below). Once you finish your 100 metres in under 1:40, then you simply start the next 100 when the red tip reaches the appropriate mark. This is how you develop a controlled pace. If you are too slow or are not capable of meeting a speed you will overshoot the target time, without having to do any time measurement or need to use a lap counting watch.

You should have noted that using the pace clock this way, your rest interval that we mentioned as point one above is now integrated into the swim pace. So swimming your 100 on 1:40 actually means swimming it under 1:40 and using the remainder as the rest period.

With a (very) little experience you get used to knowing where the different stops are. You can use 12 as your starting point just while you are learning to use the clock, but you shouldn’t continue to do so always, because all you are doing then is cheating your way into longer rests. And you wouldn’t always want to do that, would you? That’s how Master’s Minutes arise, the rest that should be a minute, but due to lack of discipline that most of us are prone to, can stretch to much longer. 

Here are some practical examples of using the clock.

Swimming 100 on 2:00? The clock finishes on 12 (or wherever it was when you started) for the start of the next 100.

Swimming 100 on 2:10? The clock advances 10 seconds for the start of each 100. Start on 12, next time it will start on 00:10, then 00:20, etc.

Swimming 100 on 2:05? The clock advances 5 seconds for the start of each 100: 12, 00:05, 00:10, etc.

Swimming 100 on 1:55? The clock retreats 5 seconds for the end of each 100. I introduced this one gradually. This is the small trick of pace clock use. To use the concept of the hand advancing or retreating (going back) for the end of each swim. If you started your 100 on 12, and are swimming on 1:55, then the next second swim will start on 00:55, then 00:50, etc.

Swimming 100 on 1:45? The clock retreats 15 seconds, quarter of a full rotation, for the start of each 100. Of course, it does advance 45 seconds, but retreating a quarter rotation each time is usually easier than advancing three quarters rotations.

Swimming 100 on 1:40? As outlined above, for this one the clock either retreats 20 seconds OR advances 40s, since subtracting 20 is usually a more regular pattern, it’s easier if you are tired. Not even thinking about advancing or retreating but simply always being on 20, 40 or 12 is easier again.

Swimming 100 on 1:35? Here you can once again use the pattern of adding 00:35 so the hand advances 35 each time. So each time it will on the opposite side of the face to last time, plus add five seconds.

These various little tricks are easier to use if you are tired or using an irregular length pool.

I don’t list a time under 1:35, because it’s most likely that if you can swim 1:40 or less per 100, then you already understand and won’t be reading this.

You will also have noticed that I only use multiples of five seconds in all the examples. Many advanced swimmers will use odd numbers  (1:23, 1:17, etc) specifically for the purpose of keeping themselves more mentally alert, while using more tightly defined intervals is also a feature of expert swimmers with a very predictable range of speeds and efforts. Neither of these are a concern for beginning and improving swimmers.

Clock animatedUsing these habits will bring you first back to the start of this section, and allow you to monitor and understand your own pace. If for example, you can’t swim your 100 in 1:55 and allow yourself a five to ten seconds rest, then your interval is too tight or maybe you are out of shape or unwell today, and you need to extend by five or ten seconds. It may also be that you are fit enough to make intervals with only a two or three second rest. If you are swimming 100 x 100 (100 metres, done one hundred times) it’s likely that your finally few decades of lengths will see you reduced to less than a handful of seconds rest. While all my examples here are short intervals the same applies to longer sets such as 200, 400 or even longer. The problem with longer sets though is that if you haven’t developed your pace to sufficient accuracy, or even if you are feeling off some day, and you are doing 800 metres or longer sets then you may not trust that you haven’t swum the distance potentially a minute slower than usual.

As a further secondary benefit, as Evan pointed out in an article some years ago, the pace clock also functions to help count laps. If you are making your interval, then all you have to count is the number of repeats. So using the example above of 10 x100, instead of counting to 40 lengths of a 25 metre pool, instead you merely need to count to 10, one after each 100.

My usual advice to new swimmers asking what lap-counting watch they should purchase, is none.

Instead, learn to familiarize yourself with the pace clock. It should become both your friend and your enemy. It will never “let you off”, never feel sorry for you, never allow you to convince yourself that you are doing better than you are. It will hold you to a standard, put your goal up there on the wall in ever repeating increments, give you a target and let you swim against yourself, and get better.

Four analogue clock faces, three showin differnt world times, the fourth a swim pace clock

What time is it?
It’s Swim O’Clock


7 thoughts on “How To: An Introduction to the Pace Clock for Beginner & Improving Swimmers

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  4. Thanks for finally writing about >How To: An Introduction to the Pace Clock for Beginner & Improving Swimmers <Liked it!


  5. Such intervals were the key to our own enjoyment of ocean swimming. On commenting to our coach that, while we knew we could “do the distance”, we weren’t confident of sustaining a pace, she had us at the pool on a slow day over several weeks for 3km time trials, giving us afterwards our 100m splits. We could thus see where we were strongest, where we tired, but above all we learned the pace we could sustain, which with further training can then improve. She used a stopwatch, but you can do it yourself with a pace clock. It was the single most influential activity in improving our swimming enjoyment. Things like this show how useful is the pace clock. It is your closest friend in a lonesome sport. Those who diss it are not thinkers.


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