Ergomo USA

Ergomo Bottom Bracket Sensor

Ergomo measures power by two optical sensor "combs" which generate square wave streams. These are compared for shifting, measured in time, and knowing the characteristics of the axle, the amount of torque can be calculated, and thus power.

An optical sensor requires slightly more sophisticated processing electronics than a strain gauge, and also care in building the sensor. It requires an air gap with a clear optical path, and is therefore is more sensitive to intrusion of dirt, water, grease, etc., so utmost care is given to cleanliness in the production of the sensor. The optical torque sensor is a non-contact sensor, so unlike a strain gauge, the active components do not need to be mounted on moving parts (the strain gauges on other power meters rotate with the crank or hub, whereas the Ergomo optical sensors can be mounted fixed and stationary in the BB shell).

1. Power and Cadence stopped working.

This is usually a sign that your BB sensor has had enough of going in circles and would like to be set free. The cause of this failure is usually dirt and/or water infiltrating the area between the photo-interrupters. Our test bed and software can diagnose and confirm this, but because the system is sealed, the best we can do is find you a replacement. On occasion, this same failure happens within a month or two "out-of-the-box". In this case, your BB sensor is waranteed, and the failure is because it was assembled with too much glue (which holds the electronics in place.)

2. Variance in Power and Cadence readings.

This is often caused by a broken wire internally. The wires don't have much freedom to travel, so readings continue as if the wire is still working.

If the power starts climbing and you think your training has just transformed yourself to Lance Armstrong, then see below.

3. Power Readings fluctuate, and average power is huge/small.

It's likely that your BB sensor is going south to Miami for the winter, maybe longer. For reasons we don't understand, when a photo-interrupter decides to go, power readings gradually grow. We can repair this issue by replacing all the electronics and wiring. It's not a inexpensive process, but when we are done, you have a new bb sensor, except for the bearings.

Another possibility is that your CPU has "dropped" the K Factor number or offset calibration. This can result in a smaller than expected average power. Go through the settings menu > Bike > K-factor then offset sensor again. On occasion, a CPU that has lost a charge may need to have the K-factor input refreshed. Also, If your CPU has just come back from battery surgery or a power outage, it sometimes takes 2-3 times before it "captures" your Offset Sensor proceedure. So, do that 2-3 times. After that, zero out the "ride" and see how the numbers look.

Another possibility is that after the BB sensor is installed, the Offset sensor has not dialed in correctly, and the BB sensor needs a few rides to get seated. I've also seen CPU's not pick-up the offset sensor. So, here is my recommendation that should remedy both possibilities:

After install, run the offset sensor and take note of the number. Do a ride on the bike 20-30 miles minimum. Run Offset Sensor again. If the number has changed, ride again. Run offset sensor again, but this time, hit the reset button on the back while the CPU is displaying the first Offset Sensor screen (background black, text white). After the reset, run the Offset Sensor again. Power numbers should be good, and the CPU shoulld be recognizing the new (and accurate) Offset Sensor number.

4. How long do bearings last?

We've seen BB sensors in for wiring repair or check-ups that have 20-25 thousand miles and are still smooth and going strong. This is about as long as one expects a bottom bracket to last, but as long as it's working there is no reason to replace it. There are five sealed bearings in the BB casing.

5. Creaking coming from area of Bottom Bracket

Creaking coming from area of Bottom Bracket: We recommend using heavy duty grease (available at your auto parts store. 1 tub = lifetime). Put a thin smear on the threads of the bb sensor on the non-drive side. And, a thin smear on the end of the sensor where it contacts the other cup. And, put a thin smear on your pedals and on the spindle where it contacts the cranks. We've had great success with this for years.