Visualising Sydney's City2Surf 2017

What is City2Surf?

Sydney's City2Surf is a 14km annual running event that starts at Hyde Park in the CBD and ends at the legendary Bondi Beach. First held in 1971 with 1,576 entrants it is now one of the world's largest events of its kind with around 80,000 participants. It attracts both competitive and casual runners and walkers. The 2017 event was on the 13th of August and was sponsored by the Sun-Herald and Westpac. Participants were encouraged to run for a charity. Links to the results of all races since 2000 can be found on the City2Surf website.

Timeline of the City2Surf 2017

The City2Surf is both, a race and a fun run. To manage a crowd of 80,000 runners and to suit each runner's ability, there are several starting groups - usually named after colours. Some start groups are invitation only or require a qualified previous running time result. Other start groups are especially for slow runners and walkers and even allow for baby buggies. There are five start groups. The start time for each group is set in a predefined schedule.

Start groups in a time lapse

SMALL MULTIPLES | Source: Results from secure.tiktok.biz | Download animation as MP4 or GIF

7:55am - Run starts
The starting groups: "Seeded, Preferred and The Sun-Herald Red" were the first to cross the finish line. Seeded runners are top athletes that are placed by invitation only. They were followed by Preferred runners that had a pre-qualification time faster than 50 minutes, which matches a pace of 3:35min/km. All runners in the Sun-Herald Red group needed a pre-qualification time of no more than 70min, which means a pace faster than 5:00min/km.

8% of participants ran in those three groups. Of the Seeded, Preferred and Red groups, 22% of runners did not meet the qualifying time for next year's competition, meaning they can not start at the beginning of the race. The average finish time was around 65min. For simplicity, those three starts are all shown in red.

8:05am - Green group starts
The "Sun-Herald Green" runners started right after the Red Start. To wear a green bib, one needed a qualification time below 90min, which matches a pace of maximum 6:25min/km. 12% ran in this group and 89% of those did pre-qualify to start again in the Green Start next year, assuming the sub 90min condition remains. The average finish time was around 80min.

8:20am - Charity Superstars start
The "Charity Superstars" are the smallest group making up only 1% of the total field. To run in this exclusive group, one needed to reach the minimum fundraising target of $1,000. Since participation in this group is based on charity rather than estimated finish times, the performance of runners varies highly. While the Charity Runners have a very exclusive run for the first few kilometres they quickly mix with runners from the Green and Blue Start groups. The average finish time was around 99min.

8:30am - Blue group starts
The "Singapore Airlines Blue" are the first start group that does not require a pre-qualifying time or a specific fundraising target. It is the largest group of participants with 31%. The average finish time was around 99min, similar to the Charity Superstars.

8:37am - First runner finishes

After 42 minutes the winner was just about to cross the finish line. Most runners of the Red group had already climbed Heartbreak Hill, while the majority of the Blue group was just about to enter the race. 64% of participants hadn't even started the run when the winner finished.

9:05am - Yellow group starts
The "Westpac Yellow" group enters the run. 29% ran in this group. The average finish time was around 2 hours.

9:25am

After 90min the majority of the Blue group was just at the middle of Heartbreak Hill. Notice how slow runners or walkers get overtaken by faster runners of following groups.

9:30am
The last group "Back of the Pack Orange" enters the run. 19% of the participants ran in this group, that was particularly aimed for participants aiming to have a fun run. The average finish time was around 2:38 hours.

9:55am - Most people on the course

After 120min, when almost every runner started the race, the field size reached its maximum with more than 47,000 runners on the track.

10:10am - Last runner is on track
135 minutes after the first runner crossed the start line, the last runner of the Orange group put their sneaker onto the hot asphalt at Hyde Park. More than 20,000 runners were already behind the finish line at Bondi Beach at this time.

12:05am - Everybody climbed Heartbreak Hill
4 hours and 15 minutes after the starting pistol fired the last participants arrived at the top of Heartbreak Hill. 83% had already finished the race at that time.

1:55pm - Run is finished
The last participant finishes the run after 6 hours. This is the cut-off time for the run. The City2Surf is officially over and all of the 67,794 participants wear a finisher medal around their necks.

Heartbreak Hill

If you have run the City2Surf before you know about the scary part just at about 6km into the race: the Heartbreak Hill – a 2km incline from almost sea level at Rose Bay up to the cliffs of Vaucluse. The hill makes the race the ultimate challenge for both the competitive and casual runner.

Elevation of Heartbreak Hill

80 metres climb along 2 kilometres

SMALL MULTIPLES | Source: User paulmilne41euphoricered3424834 on mapmyrun.com | Download graphic as PNG

Where are participants the fastest?

Most runners are fastest right at the start

Even though there are three fairly challenging hills along the first 6.2km of the race, 79% of the 2017 runners who finished the race had their fastest pace on that section. This trend is probably caused by the euphoria at the start and the fact that the runners are not yet exhausted by Heartbreak Hill.

8% of people went for their record pace when running up Heartbreak Hill. That's unexpected right? How is it possible that these people had their best pace running up the hill? It's mostly people with a pace slower than 10mi/km, which means it's mostly walkers.

Surprisingly few people run their best on the last 6 kilometres. Only 13% get their act together after climbing Heartbreak Hill and run down with their highest speed, even though there are lots of downhill sections from Vaucluse down to Bondi Beach.

How Heartbreak Hill influences performance

Let's be honest, everybody tackles the City2Surf differently. Some might put their foot on the gas right from the start until they cross the finish line. Others might just run the first one kilometre and decide to take it easy and rather enjoy the scenery for the remaining 13 kilometres. It's tough to put people in a bucket if the skills, performances and personal goals are so diverse.

However, to find patterns for varying performances, we looked at different pace groups and their pace distribution for the three sections, knowing that this is just a rough picture of reality.

It appears the faster the runner (based on the average pace), the more consistent their performance is throughout the race. This seems to be the case for running paces only. The performance of participants with an average pace higher than 10min/km vary less throughout the race.

Pace distribution

The faster the runner, the more consistent the performance on Heartbreak Hill

Pace distribution for fast runners
Average pace between 3:00 and 5:59min/km

Faster runners with an average pace between 3:00 and 5:59min/km are usually slowest when running up Heartbreak Hill. However, they seem to maintain a pace that does not differ too much from those on other segments.

Pace distribution for moderate/slow runners
Average pace between 6:00 and 9:59min/km

Similar to the fastest runners, participants with a pace between 6:00 and 9:59min/km are the slowest when running up the hill. While faster runners seem to be able to remain a pace close to their average, slower runners vary much on Heartbreak Hill.

Pace distribution for very slow runners/walkers
Average pace between 10:00 and 15:59min/km

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While runners with paces faster than 10min/km are mostly fastest on the start segment and slowest on Heartbreak Hill, this trend does not remain for paces slower than 10min/km. Walkers or runners that do take breaks during the run don't seem to be particularly faster in any of the sections. Also the performance is very wide spread.

History of participation

Looking back, the number of participants (runners who finish the race) increased significantly since 2000. The City2Surf is a run for everybody, so it's no surprise that there was always a balanced mix of runners. However, when looking at gender, there seems to be a clear trend that more and more women are interested in running.

Participation by gender

More female runners in last 6 races

SMALL MULTIPLES | Source: Links to results for years 2000 till 2017 linked on City2Surf Past Results | Download graphic as PNG

During the years 2000 to 2005 and 2007 to 2011 there were more male runners than female, however this trend has changed in recent years. There have been more women than men participating in the race since 2012. That being said, the balance of gender has been fairly even considering that the percentage of females who finish the race is between 47% and 51%.

History of finish times

Finish times by gender

High variation in number of runners for fairly high finish times over last 17 years

SMALL MULTIPLES | Source: Links to results for years 2000 till 2017 linked on City2Surf Past Results | Download graphic as PNG

There were more runners at the City2Surf 2017 than there were in 2000. But where do those additional runners fit performance wise? When looking at the distribution of finish times throughout the years it becomes apparent that with an increase in participants the number of people with fairly fast finish times also increases.

Notes about the data

For any comments or questions about the data or graphics please write an e-mail to martin@small.mu.

All charts use official results posted on the City2Surf website. Data from the latest race was downloaded from https://secure.tiktok.biz. All data was retrieved on 20 Oct 2017.

Timelapse
353 runners were removed that had a start delay of 0 seconds (same net time as gun time) and a finish time that seemed too slow (more than 1 hour) to be appropriate for a Seeded runner (those that actually started first). Some of the removed entries had finish times over 4 hours.

Only entries that have valid split and finish times were taken into account. Split point refers to the multiple points throughout the race where runners are recorded; at the start, before Heartbreak Hill, after Heartbreak Hill and at the end. 2,565 runners did have missing values and thus are not included in the visualisation. Unfortunately, athletes participating in the Wheelchair Race could not be included in the stats or visualisation as there were no split times available.

To calculate runner's distances the two split times for 6.2km and 7.8km have been used as well as the finish time to calculate an average pace for each of those three sections.

Each bar represents a distance of 50 metres.

Affiliation to start groups is calculated based on each participant's difference between net finish time and gun time. Runners have been associated with the start group that was open while they crossed the start line based on the official start times. Wrong affiliation can occur if participant's did not start in the official time window of their group. The time of day is calculated assuming the race started at exactly 7:55:00am.

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