WattBike Power difference

staggly

At my local gym there are a number of watt bike. I've found that they differ in their output quite a lot. Whilst I can maintain 260w on some reasonably easily, on others it's tough working at 235w. In the same session, I've even swapped bike and maintained a given heart rate and they are over 10% out. Looking at the watt bike site there isn't a needto recalibrated: http://wattbike.com/uk/wattbike/accurac ... alibration. I've tried the reset option on the bikes, but doesn't seem to help.

Has anyone got any tips on what to do? The difference between some bikes is that they are an older version and some newer - difference in the display mostly.

It's quite annoying really and at the moment I can't really trust the power for my training so fall back to my hear rate.

BrandonA

The numbers may be 10% different but they are only 5% out if the correct value is the mid point between the two numbers you've stated.

The watt bike from the link you've send is accurate to +/- 2% do it is possible that one is 2% up and the other 2% down and your 260 being the same as 235 is not accurate description of equal power on the devices.

I don't know what type of workout you do but could it be that some days your legs have more power in them than others? Or when you've switched bikes mid session you start the second bit fatiqued?

staggly

Fatigue from day to day may explain the power difference to some degree. But when I did a change over mid-session the latter wattbike measured higher wattage for a given heart rate. I had warmed up properly etc...

I do have a preferred machine, but there is nothing to stop someone else using it for my lunchtime hour.

sungod

that web page says it uses a load cell, which will often have a strain gauge in it (but there are other options)

it's an analogue device likely to generating very small small signals

analogue circuitry is prone to drift over time: components age, shock, temperature, humidity etc. can affect things, this is why test equipment has to be checked and recalibrated periodically

can't see why wattbike circuitry should be immune from the effects, seems perfectly possible for wattbikes to develop significant differences over time

bigmat

I have also found this - the Wattbike Pro at my gym seems to give higher wattage output than the Wattbike Trainer for same perceived exertion. I guess they can vary but its annoying when trying to stick to defined zones.

bahzob

I would suggest emailing the folks at Wattbike. I've done this a couple of times with questions and found them to be quick and helpful with their replies.

Even if they can't provide a specific answer, if this is a general issue then the more people that let them know about it the better.