Jam on the Road: Final Calibration of the Verve Track InfoCrank


On Wednesday 28 th February, some of the Jam team headed over to Hastings for a

very special trip. We’re not exaggerating when we say we flipping love the science,

so when we heard that the final calibration of the Verve track InfoCrank was but a

stone’s throw away, we jumped in the van and headed over to Novatech

Measurements Ltd.’s factory.

Not hindered by the #BeastFromTheEast, we arrived just before lunch and were

greeted by Gareth, who showed us into the calibration area.

Gleaming and sparkling in all its glory, a track InfoCrank was mid-test, weights

suspended from each arm.

The definition of calibration, according to The International Bureau of Weights and

Measures as an “Operation that, under specified conditions, in the first step,

establishes a relation between the quantity values with measurement uncertainties

provided by the measurement standards and corresponding indications with

associated measurement uncertainties (of the calibrated instrument or secondary

standard) and, in the second step, uses this information to establish a relation for

obtaining a measurement result from an indication”.

Did your head just explode? Yep. Mine did too when I read that. So, let’s put it this

way, it’s a method of comparing an instrument’s readings to the values of a

measurement standard under controlled and specified conditions. Those

measurement standards are calibrated too AND have known uncertainty values

associated with them. Each measurement result is associated with the International

System of Units (SI) via traceability, which accounts for the uncertainty of the

measurement process.

 

All pretty complicated (and that lot up there is only really scratching the surface) and a process you definitely won’t be recreating at home. The job that power meters do is extraordinarily difficult and there are many different types of power meter attempting to accomplish the same thing. How well they do this will depend largely on the importance of the various parameters that brands work around (cost, weight, aesthetics, etc.). Where materials and strain gauge placement is less optimal, then algorithms come into play; using maths to cancel out ‘noise’ (forces picked up by the strain gauges, which are irrelevant to your power output) to present you with a power reading. This does a pretty good job, until the constants, which are used by the algorithms, shift. Over time, following twisting and distorting of pedals and cranks, or large temperature fluctuations, the majority of power meters will begin to show data that is not accurate and not consistent. This is when they need to be returned to factory for recalibration or…replaced.

Unhindered by conforming to any parameters in particular, other than to make an instrument that was as accurate and precise as possible, the Verve InfoCrank was engineered to be used in the calibration process of other power meters. Hence why, once calibrated, it never needs recalibrating. The strain gauges are housed in such a way that they are not influenced by temperature fluctuations or material hysteresis, ensuring consistent data always.

We currently have a very limited stock of the Verve track InfoCrank, so get in touch if you’d like more information.