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Ergomo Powermeters and Problems in the Heat
by Denis Oakley in

As some of you may know my beloved powermeter does not always behave in the heat. I've been corresponding with the guy who developed the Ergomo and this gives a few suggestions for anyone who has had similar problems.

"Hi Siegfried, I read Andy Coggan's message on the Wattage Group and wondered if you could provide some advice and help. I am a triathlete living in Malaysia and I use an Ergomo Pro.  I offset the sensor before each ride and usually have a reading of about 800 at 0530 in the morning when it is about 24 degrees C.

 I am OK cycling until about 0800 when the sun rises properly and the day gets hot. Generally the temperature rises by about 10 - 15 degrees in a couple of hours and as the temperature rises the power readings from the ergomo become useless.(For example on a race last Sunday I did 64km in 2hours at an average of about 32km/h and produced an average of 45W!) If I > re-offset during a ride I find that the reading goes down to about 780 depending on the temperature.

 This is an irritating problem on normal long rides - but manageable - I  can stop for a drink and do a quick offset. For races it is a different matter. I will quite often end up doing the offset at about  0630 and get on the bike at 0830 and have no meaningful powerdata for the race. Spending a few minutes in transition offsetting is not something that I want to do.

Can you offer any suggestions or solutions that I could try to solve this problem?"


 "short explanation:

as you know the Sensor measures really small parts of a mm. If the temperature is changing so the dimensions of the Sensors changing, too (e.g. lenght is growing or shrinking). Furthermore the Sensor is screwed into the frame of the bike and the dimensions of the frame also changes with the temperature gradient. There are many different Bikes in the market. Sometimes (very rarely) the combination of a certain Sensor (scattering of a series) and certain Bike can produce such a effect which you experienced. 

Usaually the drift of the offset is not so big as you described.

 Possible solutions:

 - It could be helpful to change the position of the Sensor slightly from usually 9 o clock to about 8 to 10 o clock (also from 2pm to 4pm)

 In order to get a perfect power reading, it is necessary to adjust the sensor to a certain position in the bottom bracket of the bicycle. The installation position is defined through the exit of the sensor cable at 9 o’clock position

  • mount the Sensor in another bike to check
  • replacement of the Sensor

 Hope I could help you a bit.

 Please let me know if have further questions.

 best regards,



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