Powertap - here's the rub.

I recently switched from Powertap to Vector for exactly the same reasons as the OP.

I built up the PT in my deep section race rims, to which I added a disc cover when racing triathlons.

But happy as I am with the PT, in peak race season I got fed up with changing from race tyres to turbo tyre and back again. And when I'm trying to cram in training sessions around a busy job, commuting and a young family, that time matters a lot.

I find the time to change the Vectors from one bike to quicker than changing tyres, especially with latex sealant loaded inner tube to content with.

Since I do most of my workouts on the turbo (even in race season) on the TT bike in the aero position (specificity...) the only thing required is a quick wheel change.

And I can now choose whether to fit a disc, deep section wheel or even that trispoke rear I've hardly used depending on how windy it is.

Makes life simpler all round, so it was a good (if expensive) decision.

Flipping heck, I just downloaded Golden Cheetah. I could lose days in that software!!

WKO+, Golden Cheetah, Training Peaks etc

Can I ask, what software do you guys use to look at the power data collected by these devices?

All the reviews on the web show mega detailed graphs etc but from what I can see Strava premium is a bit simplistic? Trainerroad seems for indoor workouts only?

What else is there - especially to look at the data collected on an outdoor ride? Or do I need to? Other than staying in the correct zones during the ride?

Do you mean you are getting a flat band round the tyre through excessive wear? or a flat spot on the tyre? If it's a flat spot it's probably down to using the rear brake to stop your wheel. I've seen people do it out of force of habit when they finish a session. Almost guarantees a flat spot. Simplest thing to do is to wind the cam out on the caliber so that the lever moves a long way. your probably remember you shouldn't be pulling it before it hits the rim.

Oh on the power meter front, if you can afford them buy as many as you want. You don't need anyones permission to spend your money. You earned it so enjoy it.

@abudhabiChris
With my analytical head on, I may have an explanation as to why my 5s power is higher on PT than Stages: if you started and ended a short sprint with your right foot, you would potentially lose 2rpms of power as it only counts the left foot efforts whereas the PT counts everything; at low cadence this could give you a few % error (my 5s power is about 5% lower on Stages than PT), for longer durations it would obviously make less difference which is probably why my figures converge. Either way it makes cock all difference to what effort you put in and if you're using the same PM you'll get relative consistency anyway.

Or maybe it was because my best 5s power came from trying to out sprint someone who recently took home some rainbow bands from the Masters track champs and I was going absolutely balls out? I lost, naturally, but I'd beaten him the day before so I didn't mind

@Pierre - you're absolutely right, poor explanation on my part. SRM measure at the crank spider so measure all the power, but don't present it as L/R and last time I checked no-one shelling out thousands of pounds for their systems seemed to care.

@abudhabiChris - you're overthinking your algorithms; the Stages does nothing more sophisticated than taking the power output of the left crank and multiplying it by two - it can't know anything about what the other crank is doing so there's no point doing anything more complicated. Having used Stages and PT back to back for a prolonged period the only thing I noticed was a possible greater sensitivity over very short (<5s) sprints, but I think I was trying harder on the PT generally. Valid point about using what you're given, but I'm sure a team at that level could choose who they wanted as supplier.

I've got a PT as a training wheel. I use it on the turbo as that's where I get my best sessions. It's hard to ride to power on most of my outdoor rides.

If you look at trainerroad - you can train to virtual power on there from most turbos. All you need is a laptop and an ant+ stick. So you can use any wheel / tyre. Maybe you want to check occasionally that virtual and real power is similar.

Then all you need is one race wheel ?

I just throw a cover on my wheel for the races I do.

I'm sure you can get away with two and cover all the bases you want:

1. Pair of alloy training/winter wheels - these will cover outdoor use in winter and can be wet ride or turbo wheels in summer (depending on whether you use the turbo in summer);

2. Pair of deeper (perhaps carbon) wheels - main wheels in summer, and then pop them on the turbo with a cheapo tyre in winter. You most likely wont want to use them outside anyway.

So that brings it back down to the level you had expected originally. Still painful to have two power meters, but I ended up with two crank based ones too - one for the winter/wet weather bike and one for the summer/dry weather bike. So it's not unique to powertap.

Reference L/R measurement.. from too much time spent on a computrainer I know that at low intensities I am biased to my left side something like 58/42%, then, as the intensity increases, I engage my right leg more and more until at threshold intensity I am 49/51% biased towards my right leg.

I am not sure how that would look in real terms on a left hand only system, but in theory, my power reading would not be reflective of an increase in effort...

It would still be accurate to itself I guess...

Anyway, I digress... as you were.

@5th
Call me a cynic but they get paid to use stuff - it's marketing innit. All the teams get paid to ride those bikes, groupsets, saddles etc.

For all I know Shane Sutton might think Stages is the best thing in cycling since Tullio Campagnolo's wingnuts got frozen. But I reckon That Team (don't mention the name - the sound attracts trolls) has plenty of ways to get power data when it matters, whether or not they stick something on their bikes when they appear in public.

My own, possibly flawed, reasoning is that on a race bike or for race training there is sudden and intense variation. As I understand it the Left Only devices rely more on algorithms for estimates of total power so it may be less accurate for brief periods, even if over the course of 10 minutes or 2 hours it is much the same.

And I think you and Pierre are both correct. He's right that a spider-based system is measuring power throughout the stroke so it isn't one-sided BUT to get a L-R measurement it assumes that power from the down stroke comes exclusively from that side, so it isn't actually measuring L-R power, it is measuring the total and allocating it.

I agree that pedal based systems seemed to offer the perfect solution for portability and well as L-R measurement, but I've yet to hear that they've delivered.

@Scrufftie I'd be interested to know if you move your Garmin system much, or is it mainly on one bike? Several people I know have them and find the shifting process prohibitive. One guy - very experienced and technically competent - was going on a week's cycling holiday and left his Garmin pedals at home rather than take them with him, which rather defeats the purpose.

One PT is fine for me. Decent tyre on the turbo/rollers and it covers all bases from commuting to training to racing.

No power device is perfect for all situations, unfortunately. I have a PT on my main bike and now a second (winter) bike that I'm contemplating a second PT for. Crank-based was too expensive for me.
I thought a shoe-based solution would be the ultimate problem solving power device for a person with two bikes (nothing to unbolt!), until a month ago when I popped my shoe covers on for the first time this winter and realised that idea was scuppered....

Mtbtomo, there's a fair chance that if you've got a serious power imbalance between L and R legs then it'll manifest itself in other ways such as pain from your body compensating for the uneven power delivery. I don't think you are missing something, I think it's just the PM companies trying to sell you something that's 'better' when actually it makes little difference. Let's face it, surely if they're sticking to their well-publicised theory of marginal gains, Sir DB et al wouldn't sign up for something that would undo them?

If you want to get an idea of how to compare PMs have a look at DC Rainmaker's site; he's a master of the art of running multiple PMs synced to multiple head units and managing to get meaningful comparisons from them - he definitely has too much time on his hands!

As I said before, even if you knew you had a power imbalance most people wouldn't know how to go about correcting it anyway, so unless you can see real issues or have pain that you believe may be caused by this then it matters little, and I'm willing to bet a fair percentage could be sorted out by a decent bike fit to ensure cleats are set properly as I've certainly had issues with that on the MTB in years gone by. By way of turning myself into a guinea pig this year I ended up riding nearly 8,000km with a broken saddle (Specialneeds Romin Pro, shell snapped on one side of the cutout) and learnt several things. 1) I'm an idiot and should have swapped it far sooner because 2) the uneven pressure plays merry hell with saddle sores and 3) Fizik Aliantes are far comfier. But I have to say I didn't notice it leading to any crazy pedal stroke, but I know the rest of my setup is good. Bottom line: if you think you have issues get it checked out before splurging big money on a PM that will potentially tell you nothing when a setup and a basic PM will do.

Surely its about consistency? Does it matter if one leg is slightly more powerful than the other? Or am I missing something?

I've just bought a Stages mainly cos it was the cheapest system but also because I have Shimano cranks on all my bikes and have a few good sets of wheels I'm happy with. It seems like it will provide a power figure and just making training more specific.

There are so many other things I'd concern myself with before worrying whether my left leg is more powerful than my right. And a few % inaccuracy overall. Well, its better than having no idea at all like in the days of Eddie Merkx.

I'm glad to see that I'm not the only one that thinks that multiple PMs are a useful thing. I've been using a Stages since they came into the country on my training / commuting / do everything bike to good effect to record the bulk of my training load, and it also made the swap to a turbo wheel (an old wheel with a cracked rim that prevents road use but is fine with a tough tyre and cheap cassette for the pain cave) so easy and prevents any tyre squaring issues I used to get.

Unfortunately the crank on my race bike isn't compatible with Stages so I wasn't able to get any race data. Luckily I was lent a PT wheel for the majority of this season enabling me to get data on a long training camp and other training rides on the good bike.

As the PT wheel had an aluminium non-aero rim I never used it to gather race data, preferring to get the aero and weight benefit of my good wheels, but I have to say being limited to only training data made no difference and I enjoyed my best ever season with wins on the road, in TTs and on MTB (no PM on that either), mostly due to the thousands of kms ingraining the knowledge of what it felt like to sustain a certain effort for a certain time. I'd certainly like to know what power I'm putting out in races, but it's not essential. I'm hopefully going to get a proper TT bike that will be compatible with my Stages so that will change, and I hope it'll help me understand how to improve again.

I'm interested in abudhabiChris' comment about Stages not being suitable for a race bike though - surely Team Death Star's use of them contradicts that pretty effectively? I've seen enough of your work to know the level you're racing at, but if it's good enough for them it's good enough for those a step below surely?

I'm still unconvinced with the whole L/R power split argument until someone can prove categorically that they can improve on the +/-2% error per PM; i.e. potential error of 4% on a pair of pedals - if it's showing 4% difference does that mean you're either perfectly balanced (-4% taking it to zero difference) or 8% difference, and either way what are you going to do about it? Don't forget that SRM, oft referred to as the 'Gold Standard' of PMs are also single sided.

It strikes me that the ideal situation is either a PM you can shift easily from bike to bike without affecting your use of key components (pedals are the only option here it seems) or multiple PMs to suit your needs / bikes and live with the potential for error. I was personally impressed with the Powertap's reliability and battery life, but the weight of the lower versions and expense (and some extra weight) of the aero versions rule them out when I already have a pair of race wheels. Having already sunk my funds into the race bike and any spare going into a TT rig I can't see myself shelling out for another PM yet.

Vector all the way for me. Buy the left-hand only version, if you think that's all you need, and upgrade to the right-hand later.

On the subject of flatting tyres, this must be a problem with certain turbo trainers. I'm on my trainer for about four hours a week throughout the year using my 'best' tyres on mine and have no problems with wear. These are Continental Grand Prix TT tyres or Vittoria tubulars. Maybe, I'm not working hard enough!

Oh come on, lighten up, it wasn't a serious comment - so perhaps you would have understood the humour if we were face to face.

Is this a "look how 'pro' I am, I NEED three power meters" thread?

Yes that's a fair comment and I also started with one powertap and then got a second one with a set of training wheels.

I would make two mitigating observations though.

First, powertap have some good wheel tie-ins and you can pretty much get both for the price of one or at least a very big discount. This isn't meant to sound snobbish but I am unlikely to spend less than 600-700 quid on any wheels so it doesn't make that much difference to me.

Second, where you have a wheel problem with Powertap you can have a bike problem with crank or spider systems. I have a race bike, a spare bike and a TT bike where I want to see power. Two or even three Powertaps are way cheaper than three SRM, Quarq etc.

I'm about to get Stages for the TT bike but only because I think TT riding makes the left-only solution acceptable - I wouldn't use it for a race bike.

The pedal systems were supposed to solve all this but have failed miserably so far in my view.