Powermeter or Di2

As most of you know my biking needs some improvement (OK OK, my swim needs the improvement and my run is currently nonexistent due to injury). So back to what interests me...the bike.

I ride an Olympic distance race based on the "red-line" factor. I push to the max from start to finish. No need for heart rate and no need for powermeters - it's only 40K and the run as the same all out approach as that's only 10k. I don't ever slow down (although I usually lie on the floor meters from the finish for anything up to an hour after the race - sad but true, at least I know I don't leave anything out there on the race course).

However, these pesky Ironman distances take a little more science. I currently measure heart rate and cadence as my pacing factors. I NEVER look at speed until after the race and even then don't take much notice of it. If the average heart rate is kept to the target range and the cadence is kept similarly at the right level then speed takes care of itself (provided you've tapered properly, trained well and healthy come race day).

However I've come to realise that Ironman biking is about one main thing and that's efficiency, i.e. going as fast as you can without expending or wasting too much energy. So wasted energy and power fluctuations destroy efficiency which will mean that you either have a slower time on the bike than you could otherwise have done or end up struggling at some point on the run - BUT USUALLY BOTH.

So that's where the powermeter comes in - you train with it and get to know your numbers and then stick to them on race day (assuming taper, training & health of course). Heart rate is then a good aid to see how you're performing at that power output (i.e. are you having a good day = rested and healthy) and of course cadence must be maintained at the target rates too in order to complete the formula of efficiency.

There are other factors of efficiency of course such as smooth pedal rotation, stable body, aero position etc but I'm assuming those are a given by the time we get to nailing a fast Ironman bike leg.

I like seat of the pants cycling and I usually beat the powermeter boys anyway (especially on the bike section come race day). However, I'm also a numbers geek and it disturbs me to see my split times slowing as an Ironman progresses - especially where it's a course with multiple loops, the numbers don't lie).

At Ironman China, I took off on the bike with a very high heart rate and knew I was in trouble, I was going super slow although I knew there was a slight gradient and a strong head wind. My ego wouldn't let me slow down and I paid for it three quarters of the way through the bike course when all power drained away from my legs. I'd like to think that a powermeter would have given me the confidence to have slowed down at the beginning as it would have shown the power was still OK even if the speed wasn't due to the gradient and the wind.

So with that all said it brings me onto the Shimano Di2 electronic shifters. The argument for getting these is very simple - they are sooooooo cool.

So what will it be - powermeter or Di2. Science vs Ego

The smart answer is powermeter, especially as I know it'll make me faster and thus feed my big fat ego anyway but did I mention the Di2 is sooooo cool?

Let's be honest this sport is 90% the cool kit/shaved legs/Lycra and only 10% fitness/health/fun/friendship and all that other good positive stuff but 90% is a big number. (By the way if, you don't believe that then you need to go shopping - you definitely need an upgrade, hell we all need an upgrade of something).

What to do, what to do?