By Will Johnson


Well, 18 months really, but that doesn’t have the same ring to it, does it. In my last thrilling tale I had slowly worked my way up to being a master of Zwift, and contracted a rather worrying addiction to online racing. All this despite the continual hindrance of a nagging cardiac problem that means my heart rate is incredibly slow to rise when exercising and maxes out at just above 100. I left you all with the cliffhanger of whether I was a “Virtual Contender” who had discovered the secret to immense online power, or merely an “Actual Idiot” living the lie of estimated power and secretly despised by all the real virtual athletes around me…. Let’s find out the answer to this, and many more irrelevant questions in my “Year of Power”.

Well… following my follies in virtual power the only real way to find out actual facts is to get real hard figures, and not rely on Strava estimates, or Zwift Power, with all my worries about the oil in my turbo trainer heating up and distorting the figures.  The only way to do this is with a power meter.  It is interesting to note that my obsession with Zwift had grown at exactly the same rate as my new obsession with power figures and my 20 minute max output. I wondered if this interest would die at the same rate should I find out these estimated figures weren’t real.

Luckily I was able to borrow a rather amazing Specialized Quarq power spider to conduct my testing, and I as I wasn’t really sure how long I’d have it for I wanted to make a start as soon as I could get it hooked up to a bike. This task was complicated a little by the fact that this spider could only be used with Specialized cranks, which in turn could only be fitted to a bike with an oversized Specialized bottom bracket. With two already borderline geek interests in Zwift & power figures I felt that becoming a bottom bracket specification geek as well would send me over the edge of a nerd abyss from which I could never escape. So I purposely kept background reading, and mentions of what I was doing to any other human to a minimum, and came up with this plan:

I had one bike with the requisite cranks on, this, unfortunately, is my super-special bike, and the thought of sweating & straining on this machine on a turbo trainer was just too much to bear. So where could I move these cranks to, my old aluminium frame bike that was my current turbo machine was clearly out of the question, its Campagnolo threaded BB from 2006 was clearly not going to work (even though, amazingly, the bearings inside are the same size as the new Shimano threaded BB’s, meaning I could swap in Shimano bearings into the Campag BB when I ground them down to dust – oh no, into the nerd abyss we go…). The only bike that could accommodate them was my plain-special red Specialized Tarmac, only a level below the super-special but that would have to do.

These calculations were done well in advance of the magical day when my power spider was to arrive by post, and a test removal revealed that I needed to buy a very long thin T45 Torx wrench to get the cranks undone.  When the big day came I felt pretty confident, as I swapped over cranks and unboxed the spider, that I’d be power riding within minutes. Surely there wouldn’t be a specialist tool required to remove the spider’s lockring, a tool that is normally only available as part of a pack of tools & costs hundreds of pounds… I think you know the answer. So annoyed/desperate was I that I tried to construct the said special tool out of wood and nails using my Vernier calipers for precision nail placement. So very sad, and oh so close to working.

After frantically searching online I found the tool sold separately from a seller near Marseille for €48.80, so, in for a penny… I am happy to report though, that when my CKM-1009 S-Works Spider Lockring Tool arrived it was a very impressive bit of kit, an incredibly heavy, shiny, jet black cylinder that oozed quality and did the job perfectly. As you will see on the website at the first review for the CKM-1009 is for 5 stars and says “Probably the sexiest & heaviest tool that I own…”, I thank you! So, a week after the arrival of my power meter I finally got to spend my ten minutes swapping in the power spider and attaching it to my bike. Time to see what the cold hard numbers would tell me…

My plan was simple, hook up to Zwift with the speed sensor on the back wheel & heart rate monitor, connect the power meter to my Garmin on the bike and see what the difference was. I wasn’t sure how I would be able to compare figures accurately post ride so I decided to try and pedal at a constant cadence and write down what figures Zwift was giving me compared to those on the Garmin.

Now, the day the CKM-1009 S-Works Spider Lockring Tool entered my life happened to be the day after a rather glorious ride in the Zwift - WBR 2 Lap Greater London Flat Race. ( Note to reader: I first tried to write a brief description of the Zwift race to give an idea of how much fun they are. While writing I realised that I was sounding more and more like a genuine saddo who thought they really were in the final stage of the Tour de France and everyone in the world cared. So after carefully taking stock of my life, I went with it, it’s far more fun isn’t it! (All names and numbers quoted are real, or at least virtually estimated real))

After an uneventful lap and three quarters of Greater London in the lead group it had all started to kick off on the final run in. Sure, there’d been the usual opening minute at 500+ watts to weed out the chaff & some attempted breaks earlier, but we were getting to the pointy end now, and there was a definite sting in these latest attacks.

Someone tried to break from the group coming up Piccadilly, a full sprint out of the saddle, a handful of riders tried to follow. I managed to bridge the gap and stick with the new small group on the Pall Mall drag where things started to quieten down in preparation for the sprint. As we entered Trafalgar Square I’d caught my breathe a little & thought I’d go for a comedy early break just before the road starts to tilt down a little, racing suicide I knew, but I felt the others where quicker than me and probably had power-ups and fully functional hearts!

I drifted to the back of the pack, composed myself, and went. As I sliced through the group I saw the other riders react, leaping out of their seats to sprint, but somehow I managed to get a gap and kept on pushing down The Mall. I watched through my sweat drenched & fatigue blurred vision as Freddy van der Ploeg (I kid you not) was at 12-odd watts per kilo sprinting after me. The little icon with his name on was telling me how far he was behind, and it was telling me that he was catching, FAST. My power had slipped down to 750 watts after my initial patented 1,000 watt kick, I managed to heave it back up to nearer 1,000 again for the final 100 meters, but would it be enough for the victory….

Me and Freddy both clocked 39:12 with the official timekeepers at, but me & Freddy both know that his little icon still read “3m behind” as we crossed the line. Yes, the prestigious blue riband 13:35CET running of the WBR 2 Lap Greater London Flat Race was mine. I quickly took a screenshot of the leaderboard as a trophy (mainly because all riders using estimated ZwiftPower are instantly disqualified from the official results, and put in the “Filtered” section!), and took my victory warm down pedalling above a puddle of luke warm sweat in the room next to my garage. It doesn’t get much sweeter.

Sorry about that. That is to say my legs were a little tired the next day so only a low level of testing would be possible. As I set off on my first sortie I would have loved to say my heart was racing with excitement, I was a little excited and nervous, but my heart rate was in the 60s for the first minute and didn’t hit 80 until 4 minutes in, but that’s my normal. As I pedalled and glanced between screen & Garmin my heart skipped a beat (it didn’t, I’ve had that fixed), it looked like the power meter was reading higher than Zwift, much higher. All wasn’t lost, those clever boffins at Zwift had calibrated their system to a hot trainer, so when it was cold I’d actually be virtually handicapped.


Cold Turbo Trainer


Power Meter







 Pedalling at 70rpm in 3rd gear on the big ring, Zwift had me at 110w while the power meter read 120w, at 80rpm Zwift moved to 150w against 185w, in 5th at 70rpm it was 200w on Zwift against 235w from power. Pretty encouraging stuff, now I had to warm the oil up and see how that changed things.

After twenty minutes of warming up, and playing with my new power meter it was time to test again.

After 20 Minutes


Power Meter







Following the exact same cadence and gear combinations my Zwift to Power numbers were as shown in the table. With a little allowance for error, as you’d expect the Zwift figures stayed identical for the same wheel speed, while at the same time the power figures came down a little, the higher the power the bigger the difference though. That didn’t bode well for my usual rides in the high 300’s.

So how would it look with a bit more power going in? Well this is where my scientific method breaks down a little. I thought I’d just go at a few different speeds and see what the difference was. But looking back I can see that I hadn’t taken into account the fact that more power would mean more heat in the resistance oil, so the more I tried higher power bursts the easier they would be, and the further they’d be from Zwift.

Bit More Power


Power Meter







Here are a few random figures, I didn’t note in which order I did these in, so the oil may have been at different temperatures. The long and the short of it is that my 440 watts on Zwift was at most 360 watts of actual pedal power. I say at most, as I imagine after properly pounding around on Zwift for an hour the oil would be hot enough to fry an egg, and pretty poor at resisting me pushing. The Zwift power curve seems to be much steeper than reality, with the crossing point at about 250 watts when warmed up. The further away you get from that, and the hotter the oil is, the further the readings are out. Oh crap, my patented 1,000 watt kick might be only 600 watts, that doesn’t have quite the same weight to it does it.

So I wasn’t a Virtual Contender, how did that make me feel?

To be honest, I was a little bit deflated. I kind of knew that I couldn’t conceivably be putting out those kinds of big numbers while at below 60% cardiac output, but I’d been on the same setup all along and watched my performance creep up from below 200 watts, so how could it not be right! Also, it’s nice to be good at something, and to work back from heart surgery & near crippledom to a point where I could mix it with decent riders again genuinely excited me, and certainly got me working hard.

In fact, as a motivational tool the “over reward improvement” model had a pretty amazing effect on me, making me come back to Zwift as soon as my legs would allow, to try and up my numbers. I don’t know if there’s any way to work this into the Zwift system, maybe users could get power-ups when they’re pushing a certain percentage over their normal threshold. Although I’m sure that if it did come to fruition certain people would artificially lower their “normal” numbers just to get a bigger boost for the big races. I feel a bit like a virtual David Millar, I’m a former (albeit unknowing) virtual race cheat now berating potential future virtual race cheats in a hypothetical virtual situation. Not a particularly secure position to be in, whatever would Freddy van der Ploeg think!

The question is, how would knowing that I wasn’t “a conteneder” any more, and the fact that I couldn’t mix it in the top group affect my Zwift addiction and newfound obsession with power….

Well, in an annoyingly predictable way, enormously is the answer. I had a few goes on races, lowering my level down to C, and I did have fun racing against guys in lower groups, sometimes holding on to the lead group on flat sections only to be dropped on the inclines. But it wasn’t the same. I felt a little bit like the big kid at school, who find sports a bit less fun when everyone else grows up to be the same size. Anyway summer was round the corner and I had a power meter to play with outside in the sun.

First things first, I had to find out what my power figures were in the real world. First trip out I was more than a little transfixed by the little numbers rising and falling in front of me, and my first reaction was that I had a very limited gauge of how hard I was actually pedalling. Being of a certain weight I understood that going uphill wasn’t going to be my strongest area, but I never realised that even small changes in gradient would have such a massive effect on my power output. I found that as I tootled along with my power in the high 200’s a small rise where I naturally tried to maintain my speed meant my power would shoot up to nearly 400 watts.

I don’t think there’s room here for any more of my oh so interesting power meter observations, you’ll have to wait for part one of my eight part “Fat Man’s Guide to Cycling” compendium ( free Pukka Pie with part one) to find out more. Suffice to say I became a little bit obsessed with my new power toy during the summer, judging climbs on power, assessing time differences, generally annoying everyone around me with power meter talk, and barely looking up from the numbers to take in the beautiful scenery.

As we came to the end of the summer, and the true test of whether I would make a return to Zwift and eek out lunch hours and weekends in little tussles with online adversaries, a little bit of back pain crept into my world. After my rugby career with things snapping, tearing & breaking left right and centre, and resulting operations to fix them, then with my recent series of heart ops, I had decided to try and be less gung-ho about my body and try to let it rest and heal without pressure or scalpels.

So I rested, didn’t cycle, started doing yoga stretches, all the right things. But this lingering little bit of back pain got worse when I tried to stretch it, worse still when manipulated by a physio, then started to turn into numbness down the back of my left leg, and my calf muscle not working properly. So finally I succumbed, had an MRI & went to see the specialist, a specialist who I’d chosen specially as he wouldn’t operate unless it was absolutely critical to do so. It was a Thursday two weeks before Christmas, he said I had a herniated disc which was touching the nerve and needed an operation soon to stop my nerve dying completely. I said “When, in the New Year?” he said “Tuesday” – message received and understood.

Little tip to anyone out there who gets prolonged pins and needles (amusingly, called “ants” in French), numbness or muscle dysfunction – go and see a specialist. As my specialist explained, these can be symptoms of impingement & damage to the nerve, which if allowed to continue could lead to the nerve dying, making temporary discomfort permanent.

So, annoyingly, much of December and January was bike free, I did manage a few illegal Zwift rides, complying completely with the surgeons instructions not to stress the repaired disc by bending too much, and certainly not to risk falling off a moving bike. The hardest part of complying with those instructions was actually getting on & off my turbo bike, bolted upright so I couldn’t lean it over, and wearing cleated shoes on a tiled floor is a recipe for disaster. I did attempt my showpiece wheelie mounting technique (put the bike’s front wheel in the air then manoeuvre the seat post between your legs before putting the front wheel back on the floor leaving you astride the top tube) but with the back wheel fixed and the turbo in the way the resultant shuffling and increased risk of groinal impingement made this a very poor choice!

Making yet another comeback on Zwift did rekindle some of my love for virtual racing, I discovered Cat & Mouse races where the slower groups go off first and try to stay ahead, races that built in intensity, open races and even something called social riding… But the spell had been broken, Zwift was just a pleasurable way of riding my bike until my back and the weather improved enough for me to go out into the wild, and maybe that’s for the best.

So where does this leave us? As I write this my experiments with power are continuing, and I have also ventured into new territory, something I call “sub-maximal riding”. I don’t believe anyone anywhere has ever tried this, but it basically involves not riding so that your legs explode every time you go on your bike. I know, pretty revolutionary stuff. Find out about this and so much less in my next instalment.


December 10, 2019 — Ollie Gray
Tags: Road/CX