I’ve been struggling for a little while now – I’ve got a problem.

I haven’t bought any running shoes since… since… well… I can’t even remember, it was that long ago! (I’ve just looked, it was April… four whole, long months without buying any running shoes.)

So… I’ve been trying to identify a need for some new shoes.

I have road shoes…

ASICS Gel Nimbus 17
First run: 11 November 2015
Total runs: 47
Total miles: 229

These were my first shoes in quite a while that weren’t made by Brooks – I was pretty suspicious of them to start with, but I’ve got used to them now!

Brooks Glycerin 13
First run: 30 April 2016
Total runs: 34
Total miles: 155

My third pair of Glycerin’s, after a couple of pairs of Glycerin 11s. Unsurprisingly given that, I love them, and plan on replacing them like-for-like.

… and I have hybrid trail shoes …

Brooks Cascadia 9
First run: 4 June 2014
Total runs: 64
Total miles: 249

It was genuinely a coincidence that these ended up being Brooks – they were, in fact, the only trail shoes in the (pretty crap) running shop that I went to. (They also need cleaning.)

… and I also have more aggressive trail shoes.

Salomon Speedcross 3
First run: 12 April 2016
Total runs: 6
Total miles: 22

These were bought after the Cascadia 9s… under-performed on a couple of runs. Nothing too dramatic, I just realised that I needed something a bit more robust for some of the terrain I was going on.

So anyway… I generally find that for me, around 350 to 400 miles is the limit for a shoe, which still leaves at least 100 miles in each of my current pairs, so I’m obviously not going to be replacing any of them anytime too soon. Which got me thinking about racing flats.

No, no, I don’t mean contesting apartments, I mean the lightweight running shoes. Like… to pick a racing shoes completely at random… the Brooks Hyperion. They weigh just 181.4 grams – that’s compared to the 320.3 grams of the Glycerin, and 353 grams for the ASICS. Per shoe.

And that matters (apparently). Top running coach boffin Jack Daniels worked out that 100 grams per shoe makes running about 1% harder, or adds over 1 minute during a marathon. (The Run S.M.A.R.T. Project).

Now, I don’t run marathons, and I’m not even sure that I would fancy a lightweight shoe during a half marathon. But what about a 10k? How much difference could it make?

I tend to race in my Glycerins, so we’ll start with a weight of 320 grams. The Hyperion is 181 grams, so a difference of 139 grams. So, with some ballpark maths: if 100 grams gains just over a minute, let’s say 1.2 minutes, then 139 grams will gain about 1.6 minutes. A 10k is roughly a quarter of a marathon, so around 0.4 minutes, or about 24 seconds. Or 12 seconds in a 5k.

Now, some more maths. The Hyperion is around £80. Meaning that I’d be paying just over £3 per second of advantage during a 10k.

You know what, this clearly isn’t going to convince Lolly at all…