Posted by: Ian | July 15, 2012

The effect of the bike, the effort, the season and training on cycling speed

This will be my last post for a while to feature charts, which have perhaps been overused in recent entries. Before shelving the graphs, here’s one piece of analysis of my own rides that I think will echo the experience of many regular cyclists.

A couple of years ago I started recording Park Loops as separate Garmin activities, isolating the 10 mile blast 3.5 times round Regents Park from the rides to the park beforehand and the rides on to work (often via Look Mum No Hands) afterwards. Excluding the times that for one reason or another are a bit funky, I have now 46 comparable 10 mile Park Loop ride records.

At first glance it’s not super straightforward to disentangle a pattern of improvement (or the opposite) from the effect of being on one bike rather than another and other factors:

This isn’t too surprising as when you’re cycling round the effect of the wind and the number of times you have to stop at traffic lights make a huge difference. However, with a bit of simplification a few clear patterns emerge.

First, it really is about the bike:

The five or six fastest times are all recorded on the fastest bikes, notwithstanding the fact that I’ve done Park Loops on the fantastic but heavy and ungeared Tempo far more often. (The slow time on the Cervelo occurred when the winds were super fierce.)

Next, just taking the Tempo rides and looking again at how the times have changed over the last two years produces the following chart, with the blue line of best fit plotted through the points.

To me, this very clearly shows the superposition of two factors: First, there is a clear seasonality effect, with the times around Christmas/New Year being the slowest both years. This is what you’d expect given that the weather is much worse in Winter and also, like most cyclists, I’m generally in better shape in Summer. The second factor is an improvement in form over last year. Whereas the Summer 2011 times are about the same as those in Summer 2010, the Winter and Summer times so far this year are looking much better. Numerically, the midsummer speeds are about 1.5 minutes faster than the midwinter speeds; the 2012 improvement in form accounts for up to a further minute.

Finally, by tracking the ride times against average Heart Rate the effect of trying more or less hard can be teased out:

The red fitted line indicates that jacking up my heart rate by 5 bpm can buy maybe a minute over a more relaxed ride: trying harder works.

I could tease a mathematical model out along these lines but the information value wouldn’t be much greater than you can readily read from the pictures.

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