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First look: Goat Race hidden motor (video)

27 Nov 2017

A very ordinary bike, with some extraordinary tech beneath the surface

This may look like a run of the mill aluminium bike of middling spec, but it’s probably the fastest bike we’ve ever had in the Cyclist office.

That is largely because of the hidden motor housed within the bike’s seattube. British-based Goat Bikes has designed and assembled the bike, but with a Austrian-made Vivax-Assist system, which Goat Bikes distributes in the UK.

The Vivax-Assist is a hidden power motor within the seattube to power the cranks. The system turns a bevel fastened to the axle of the cranks and generates 150 watts of output to assist the rider in maintaining a given cadence.

Concealed motor

The motor battery and control junction are concealed in the bottle. From there the system charges, and the main power switch is turned on or off.

To activate the motor, the cranks need to already be moving, otherwise the motor will detect too much resistance and turn off. 

The motor does not work as one might assume. Instead of detecting the rider’s input and generating appropriate assistance as a Bosch motor on a e-bike would, it works to maintain a pre-set cadence.

So, if the system has been programmed to hit 90rpm, it will work to sit at that cadence regardless of the power the rider puts in. We'll discuss how to set this cadence level in our in-depth review, early in the new year.

The motor and battery weigh around 2kg in total, pushing the overall weight of the bike to 10.2kg without pedals (on our scales).

The added assistance of the motor easily eclipses the extra weight though.

The frame itself has been specially designed to tolerate the extra twisting forces of the motor within the seattube. Clamps are also necessary for the bottle-cage battery as bottle bosses cannot rivet into the motor.

Motor doping

One can’t glimpse at this system without considering motor doping, for which this model of motor has been put to use on several occasions. However, this certainly is not the idea behind the motor.

This was the system found housed within the spare bike of Femke Van den Driessche at the 2016 UCI World Cyclocross Championships, and resulted in a sanction for the rider.

The same system was found being used by a French amateur earlier this year

Goat Bikes doesn’t endorse any sort of cheating with the system, and brand owner Steve has described most of his clients as older riders keen to keep up on club runs.

Vivax Drive confirms that the main global customers for its motor unit are riders aged over 60.

‘Most of my customers are coming up to retiring age and definitely cycling,’ he explains.

‘This is definitely for the cyclist that wants to continue cycling and continue to keep up with the people they’re cycling with now.’ 

This bike is essentially a discreet e-bike for road riders.

We’ll be testing the Goat Race over the next few weeks to see how the motor works, how effective it is on a variety of terrains and how likely it really is that it’s ever been used in a pro peloton.


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