I’ve got the (Virtual) Power!!

Trainer Road User Interface

I’ve had a lot of messages on Facebook, Twitter and TriTalk about my use of Trainer Road software and Virtual Power, how to set it up, is it any good and does it do the job.  Hopefully this will answer all that and more!!

One of the best tools a cyclist or triathlete can have is a power meter and as important, the knowledge of how to use it.

As a middle to back of pack triathlete I’d always seen power as a nice-to-have, but not anything that would necessarily benefit me a lot.  However now I’ve got a coach setting my programme and analysing my sessions, power adds a whole new dimension to how you rate your form, how you motivate yourself in a session and importantly how you pace yourself in a race.

But here’s the downside.  Up until now, for a wheel based system you’d be talking up to £1000 and for a crank based system £1500-2000.  Definitely not a tool that is a nice add on for your regular triathlete – it is a significant investment in your training, and you need to ensure you’re getting everything out of such an expensive tool.

However in recent months, some cheaper power meters are starting or due to be on the market.  Crank based systems such as Power2Max or some new innovations due to come to market in the next year which have a small insert into the left crank arm, or a pedal spindle insert promise to bring this important tool down into the price bracket of the average age grouper.

But what if there was a system that told you your power on a turbo trainer for the price of a family meal out?

It was a month or two ago that I found out about a piece of Software called Trainer Road that promised just that.  It uses ANT+ the protocol now used for the majority of cycling devices (if you have Garmin bike or multisport device, ANT+ is used to connect to your PC).

The pieces of kit you need are an ANT+ USB dongle that plugs into your PC (such as the one used to link to your Garmin) an rear wheel mounted ANT+ speed and cadence sensor (Garmin and Bontranger make them for £25-30 if you shop around) and Trainer Road will also connect to your ANT+ Heart Rate Monitor belt to record HR but this isn’t necessary for the Virtual Power Calculation.  Once you have these, you just need a Turbo Trainer that is on the comprehensive Trainer Road List of 256 approved Turbo Trainers.  My Turbo is about 8 years old, but I still managed to find it on there.

So how does virtual power work?  Well a power meter works by measuring the force applied to the cranks (the torque as the force is applied in a circular motion) and the speed or rate that the force is applied (as torque is measured, the rate is the cadence of the pedal stroke).  This results in a figure in Watts which is your power output which is independent of speed across the ground, what gear you are in or how windy it is, so it is a good constant to measure your fitness by.

Virtual power reverse engineers this, by knowing the power curve of a particular Turbo Trainer (i.e. if the particular model of Turbo is going at 20 mph, it requires 200W of power to generate that speed which is independent of rider).  So getting the correct model of turbo with the right resistance is key for the figures being accurate.

Trainer Road works all this out in real time on your laptop screen, by having a piece of software on your PC or Mac reading the ANT+ information in and displaying a graph of your real time power output and other metrics.  For this service they charge $10 per month subscription.

Trainer Road Setup

Is it any good? I’ve done around a month’s worth of training on it now and although I’ve not got a normal power meter to calibrate it against, the figures I’m getting out seem to be correlating with my heart rate figures and are consistent across zones.  For my purposes, as long as I don’t change my setup now, this should give me a consistent power training environment for my coach to set my sessions and analyse the results, even if it was a few Watts out with actual power.

Working with my coach we did a 20 min Functional Threshold test and my Functional Threshold Power came out as 250W.  I was quite pleased with this until I found out reading his Autobiography today that Bradley Wiggins’ FTP is 470W!!

The Trainer Road software allows you to download your power file down (including any other metrics – speed, cadence, heart rate, distance) as a TCX file and upload into software such as Training Peaks – I do this so my coach can analyse my session.  The interface has a great on screen display of your metrics, a library of workouts to pick from, although I use the 1 or 2 hour Free workouts as my coach will have already set a session for me to do.  There is a workout designer coming soon that promises the facility to create your own custom workouts.  The software also integrates with Sufferfest videos displaying the wattage (related to your own FTP) required at each point in the video.  If you’re a Sufferlandrian, it’s worth the $10 it just for that!!

Overall, if you have a Turbo Trainer on the list, this is a very cheap way of getting legitimate power figures to analyse and motivate your Turbo sessions.  My only issue now is that when I do get out on the road, I’m missing my power figures – looks like I could be asking Santa for something…and if it’s an ANT+ power meter, it will still link in with the great interface on Trainer Road!!  If you’ve got the required kit already, what are you waiting for?

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