London Triathlon by my numbers

I’m a bit of a geek; I love run tracking and find it incredibly satisfying to see all the numbers and data behind my runs and races. I probably rely on the numbers a little too much during a run, and can get caught up in making sure that I’m on pace, but I also find it very helpful when you’ve got a certain goal time in mind.

That’s why I was very happy when Suunto lent me the Spartan Sport Wrist HR to wear for the London Triathlon. I had set myself the target of a sub-2:45 Olympic distance time, with interim goals of a 28-29min swim, sub-1:20 ride and then a ‘just-go-as-fast-as-you-can’ run. With the multisport functionalities of the Suunto including a ‘Triathlon race’ mode, for the first time I was able to get feedback on how I was tracking against those targets during the race.

We had to tread water for 4-5mins before the start of the swim, so I used this opportunity to switch into triathlon mode and let the Suunto connect to GPS. As always, it quickly found the signal and patiently waited for me to hit ‘start’ when we set off. Once we were going I didn’t actually look at the watch at all, so still have no idea of the data that the watch shows you for an open water swim.

Looking at the triathlon data afterwards, you can see exactly where I zigged and zagged and had to re-adjust my course instead of taking the most direct line! It reported as 1658m on MovesCount, and although unwanted, I can believe I swam an extra 158m through all the misdirections. When transferred over to Strava (via a Bluetooth connection on the app: very easy to use) it reports as 1682m, a negligible difference. I’m most interested in those two spurts at 800m and 1500m – turning around the buoys seems to get me excited and moving a lot faster!

To switch into the next leg of the mode on the watch you press and hold the top button (usually pause/stop) until an indicator circle completes loading. I got a bit distracted by trying to do this, and whereas everyone else’s swim photos show them unzipping their wetsuit, I’m just staring at my watch (oops)! This T1 section ended up being transferred to Strava but I deleted it, lest anyone think that I did an activity that only lasted 3.5mins. Gotta keep up endurance appearances! (Haha I can be really silly sometimes.)

Another press-and-hold before mounting my bike (just go Julia!) kicked the watch into cycling mode. With no markers on the road, I found myself periodically checking the watch to see how I was tracking against my goal, which required me to maintain a 30km/h average pace and to complete 5km every 10mins.

Unfortunately, every time I checked the watch the data I saw said I was riding too slowly. At 5km, the watch said I had been on the bike for 13 minutes, and on other occasions I often saw speeds of ~25km/h despite feelings like I was pushing hard. These numbers didn’t make me feel great, until I realised that the route had taken us through a number of long tunnels and through tall city buildings. With all that interference, the GPS signal must have dropped out a few times, as the ride ended up tracking at 33.7km (instead of 40km).

I do find that 6.3km difference a bit high though, and I would be interested to see if other participants tracked the course to a similar distance. It would be great too if the Suunto had an additional way of measuring distance even when GPS signal drops out; I imagine this may come with adding cadence sensors to your bike wheels, which I don’t have.

I remembered to switch legs coming into T2, although I was a little annoyed by having to press-and-hold to change. I think it would be much easier just to press the ‘lap’ button if in race mode, as it took some concentration and coordination to hold down the button whilst also trying to run with a bike. Interestingly, my T2 never synced to Strava (not that I wanted it there anyway!)

Out on the run I had set the watch to beep at 1km intervals (I find auto-lap good for races, but not training), and the first one came in saying I’d just run a blazing 3:27/km – I don’t think so! Again, I think this is due to GPS issues as the transition area was inside the ExCel centre where signal would not have been as strong. You can see on the final map too that the start jumped across the Royal Docks, which backs up my theory.

The rest of the splits beeped at more reasonable intervals, despite approx 1km per lap taking place inside the ExCel centre. The final distance recorded on the Suunto was 9.87km, close enough to the official 10km distance. However, when I then synced the move with Strava, the results were different. Strava reports a 7.9km run with very odd splits, which I think is from it not being able to calculate those indoor sections. I would love to see Strava and MovesCount have a closer parity when it comes to reporting activities, as it feels frustrating to have ‘lost’ 2km of my triathlon run.


Overall, I did like having the Suunto during the triathlon, as it gave me extra information on my wrist which I wouldn’t normally have. Knowing that I was doing well did me the confidence to keep pushing and achieve my goal. I am a little disappointed that it had so many GPS issues, particularly on the bike leg, but that there could have been many external reasons why this occurred. Oh – and I have to congratulate myself on getting the lap timings fairly accurate!

Note: I was sent a Suunto Spartan Sport Wrist HR to wear and test in the weeks surrounding the London Triathlon, however I was not paid to blog about it and all opinions are my own.

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