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Hidden motor vs super bike (video)

Peter Stuart
9 Jan 2019

How much difference does motor doping make? We pitch a concealed motor against a WorldTour race bike to find out

It all began on Saturday 30th January 2016. That was the day U23 rider Femke Van den Driessche’s spare bike at the Cyclocross World Championships was inspected and a motor was found inside. It was unprecedented, and has changed the way we think about cheating in cycling.

The system she used was a Vivax-Assist motor. The motor, situated in the seattube, works by turning a bevel gear fastened to the crank axle and gives a power boost of around 100 watts.

It is a technology that has been in development for years – largely aimed at a market of older riders keen to maintain their normal riding pattern while losing fitness.

Since the curious incident of Van den Driessche, we’ve seen two further incidents of a Vivax system used in competition for unfair advantage, both by amateurs.

Today, it is expected that UCI president David Lappartient will announce new tests to help quash the suspected use of motors in professional cycling promising tougher sanctions.

But what Cyclist want to know is how much of an advantage does such a concealed Vivax motor really offer?

We put the Goat Race with the Vivax-Assist within it up - ridden by me - against a Bianchi Oltre XR4 - ridden by my colleague James Spender - on a steep hill-climb, both with and without the motor activated to see what difference the motor offers

Goat Race Ultegra (with motor), £4,999

We didn't use power meters, or timing on the climb, but instead looked at how the system feels, and looks to the competition, when used against a conventional bike.


As we established when first testing the system, it requires more practice and skill than a more complex pedal-assist system. It also requires an aluminium frame or an internal aluminium sleeve to secure the motor in place.

While the motor is not in use, it engages a freewheel, but the bevel itself must still be turned by the force of the axle. It’s a tiny level of resistance, but one that might be palpable over 100km of riding.

There is also a heavy battery unit that must be attached to the motor. In this case it’s concealed within the water bottle.

Consequently there are a few sacrifices to a concealed motor.

The bike we’ve tested is the Goat Race, UK-based Goat Bikes has designed and assembled the bike with the Austrian-made Vivax-Assist system integrated within it.

Goat has made a fine aluminium bike, very well adapted to the motor, but with the added weight and lower quality material this certainly isn’t a World Class bike when the motor is off.

It weighs 10.2kg but has a concealed motor which can give over 100 watts of assistance.

The Bianchi, by contrast, comes in at 6.8kgs with aerodynamic tube shaping and stiff deep section Campagnolo Bora wheels.

Bianchi Oltre XR4 Super Record, £9,500

The motor has 200 watts capacity, but owing to the cadence-based boost and presumably some transitional losses, we’ve generally perceived the boost to be closer to 100-120 watts.

It’s nowhere near as powerful as the enormous Bosch motors we see in e-mountain bikes and in the emerging class of e-road bikes.

On a good day, James is a little more explosive than me, and so I’d expected him to edge ahead of me without the help of the motor, especially on the lighter and stiffer Bianchi.

With the motor on, though, we expected it would be enough to bridge the gap between both our bikes and our physiologies. The interesting measure was to find out by how much...

On a short steep climb like this, though, the motor is pushed to its limits in terms of torque, and the extra weight of the Goat does have all the more influence.

Turbo charged

While there’s no question that the motor makes the Goat faster, the important question is how dramatic such a boost is. Could WorldTour mountain attacks or sprints up the Koppenberg really be explained with a concealed motor?

While there are watts on offer, the power difference required to sprint away from World Class riders is substantial, and does the Vivax offer that sort of boost?

Equally, could it let an amateur rider compete with professionals?

As our video suggests, there is certainly an advantage to be had, with a two bike length deficit turning to a one length lead. But three bike lengths over a few hundred metres isn’t enough to split a WorldTour field, or allow an amateur rider to compete with elites.

Of course the motor requires a certain skill, and by resetting the cadence that the system works toward (more on that here) I could maybe match the lower cadence demands of a climb like this.

With the specific output of the motor requiring a smooth rotation of the cranks my climbing style looks a little unusual compared to my first run and could give away a cheat on close inspection.

The noise, however, was not a giveaway, as the Vivax-Assist is far quieter than its predecessor, the Gruber-Assist.

On the whole, though, it remains difficult to imagine top pro cyclists relying on a concealed motor system such as this – given the relatively conservative gains in power versus the numerous disadvantages and the visible difference in pedalling technique that might give the motor away.

But, of course, stranger things have, and do, happen.

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