It’s a question that comes up quite a lot in the Zwift community! How does the real Box Hill compare to the Zwift version? Will riding London Loop on Zwift help me train for Ride London? I’m lucky enough to have ridden both climbs numerous times with the same power meter (a very reliable PowerTap G3 hub) thus have some  meaningful data to compare the two. This weekend I got number crunching.

First up a bit of real life riding:

Box Hill Roundabout to Cafe (2.8km @ 5%)
https://www.strava.com/segments/1450512

Watts: 237W
Time: 8 min 50 seconds (cadence 81rpm)

This particular effort was in the middle of a stark British winter on a 115km club ride with Woking CC. I was rugged up in a lot of warm clothing and had already climbed Staple Lane followed by Ranmore Road (both Cat 4 climbs) in the Surrey Hills before hitting Box.

I was still pushing hard of course with a small group to get to the top for some steaming hot coffee and home made cake. As you can see from the photo it was a pretty bleak looking day for a ride! Cold, wet, foggy and grimy. Ahhh those romantic hardcore UK winter rides before we all got soft…

Now for the VIRTUAL version:

Zwift Box Hill Real KOM (2.9km @ 5%)
https://www.strava.com/segments/13812242

Watts: 230W
Time: 8 minutes 10 seconds (cadence 79rpm)

Ridden as part of a Zwift race where I was trying to stick with a small group of 4-5 other racers at the time, this ascent of the virtual hill was actually a PR for me. My setup is Elite rollers with my PowerTap measuring wattage. I was pushing hard, but pretty gassed after the SUPER HARD start that makes up a Zwift race. I didn’t use any power-ups during the climb.

Evaluation of real life vs Zwift life:

With pretty much the same cadence I averaged a 7 watt difference over the two efforts, which is well within an acceptable margin of error for measurement.  As you can see there is a 40 second difference in favour of the Zwift climb for me (the virtual segment is also around 100 metres shorter). This is roughly what I would have expected from the data I have collected and my percieved efforts over both of the segments. On a fair summer’s day (with less clothing, lighter bike, etc) I would knock a chunk off the real Roundabout to Cafe segment – and have done – thus getting closer to my virtual time.

So what can you take away from the data? Training for Box Hill or similar climbs by using the Zwift virtual Box Hill climb would actually be pretty effective, especially if you have a smart turbo that changes the resistance settings for you. Time-wise you can expect to spend a bit of extra time laying down wattage when you get out to Surrey for the real thing. Also the Zwift climb finishes past the National Trust cafe! You’ll definitely want to pull in there for the best treacle tart in the world… :-)

See also – The Sufferfest

END NOTES: For reference I weigh in at 60kg so was climbing at just under 4w/kg. I’m no powerhouse. I chose these two segments rather than the Zwiftblog verified one as they were the two closest matched ones for distance I could find on Strava.

EXTRA TIP: Don’t ride over the squiggly white line painting when you do the real Box Hill climb. It’s actually pretty bumpy and will kill your speed…