In the wake of the seemingly renewed post-race examinations for 'mechanical doping' by the UCI, I was wondering if anyone has experience with the motors in question (like the Vivax Assist - thanks, Kibbee). More specifically, would they be able to contribute to a pro rider's effort at race pace or is there an upper limit to where they're able to contribute?

Personally, I think the whole mechanical doping 'issue' is rubbish, but I'm curious. Taking Cancellara's attacks during the 2010 Spring Classics as an example, at the time when he supposedly turned on the motor, he was imaginably already doing several hundred watts. Would a motor, small enough to be hidden in one of the bike tubes, even be able to contribute to that effort?

Is it the case that if I had one of these motors in my seat tube and I was riding at 300 watts, would turning on the motor bump my output up to 400 watts; or is there a point of diminishing returns?

  • I think for "mechanical doping", they'd be looking for devices such as the Vivax Assist. Which can be concealed in the seat tube, rather than quite visible hub motors. Most e-Bike motors are purposely limited to lower speeds to increase safety, but I'm sure a motor could be designed that would help a professional rider if that was the goal.
    – Kibbee
    Jun 10, 2015 at 19:35
  • Yeah, I understand that the motors they're looking for are the hidden seat tube type, like the Vivax. But even with the Vivax Assist, the performance looks like it drops off rapidly with a cadence above 90 RPM.
    – Ealhmund
    Jun 10, 2015 at 19:40
  • You can still go pretty fast even if you keep the cadence below 90 RPM, provided you are in the correct gear. This could be very useful when doing things such as climbing. It probably wouldn't help much in the final sprint where they are spinning in the top gear at high cadences. Also, the Vivax assist is probably optimized for 90 RPM and below, because that's how people will use it, but they could probably also design one that would work at 100 or 120 RPM if that was the design goal.
    – Kibbee
    Jun 10, 2015 at 19:46
  • 2
    Diminishing returns and cheating are not the same. If the motor slowed a rider down that is still cheating. If drugs intended to improve performance actually decreased performance that is still cheating.
    – paparazzo
    Jun 10, 2015 at 23:03
  • 1
    A hidden motor was found at the Cyclo-cross World Championships - bbc.co.uk/sport/cycling/35452791
    – Tom77
    Feb 4, 2016 at 8:23

2 Answers 2


As far as assisting at race pace - a cadence of 90 or 100 is not a limit for an electric motor designed for it. With the dollars involved in cycling generally, and at elite sports specifically, I do not see any barrier from an electromechanical perspective. Most importantly for an elite rider, the motor can be optimised for a cadence between 85-95 - a very small range.

I would be less concerned about a 200W Assist over a short time, as it would be rather obvious, than a net (factoring in extra weight) 20W or 50W assist over the duration of a tour. Imagine if you could give a rider a drug that instantly gave them and extra 10% output over an entire tour? This motor could be small and hard to detect. Its heat signature would be tiny. A physical bicycle inspection would be needed.

Current battery technology limits the capacity available without obvious signs - physical size but also the weight would make the bike move differently to normal. I am sure an experienced observer would spot it. However, research into battery technology is progressing very quickly. Its foreseeable within a year or two batteries with 10x capacity for no weight or size gain will be possible. recharge times are plummeting to measurements in minute to full charge.

So should they be worried Absolutely- today I think the risk of you or me doing something and being caught is high, the hardware is too big and bulky and obvious. A simple weight test of the top riders bikes would suffice. However the dollars involved at the highest level, and the scale and length of time the cover ups and secrecy around Lance Armstrong's drug use were able to continue do not preclude a team spending a large amount of money into secret commercialisation of research results.

Within 10 years, I believe the average road or MTB will have an electric assist option as it filters up from the commuter/casual market into main stream. From there, its a tiny step into the race scene.

  • 1
    A weight test wouldn't suffice. Bikes already frequently weigh less than UCI regulations, but weights are dropped into the seat tube to meet the minimum. Per the article linked by @altomnr, a motor and battery capable of delivering 165Wh of energy can be had for under 5lb. The UCI limit is 15lb, but carbon fiber racing bikes weighing under 10lb can be bought today. A rider could easily use the motor just for climbs (offsetting its weight), and disable it on the flats where the extra weight is of no consequence. Jun 11, 2015 at 1:39
  • 1
    Even the smaller one (at 110Wh for 4lb) would be an incredible help. Two hours of an additional 50W (around 27W/kg, compared to an elite rider who can sustain less than 7W/kg for long climbs) could easily be the difference between a pack finish and winning a race. Jun 11, 2015 at 2:01
  • More than two hours, if you imagine a big competition like the Giro, even if they only use this in half the stages that is a big, big help.
    – super
    Jun 11, 2015 at 18:27
  • Fast foreward 5 not 10 years: EMTB has surpassed Fatbikes is popularity. I weep.
    – Vorac
    Jul 10, 2020 at 7:52

The motor doesn’t have to contribute to upper limit riding. Click the motor on and spend the first half of the race freewheeling at 200W and save your legs. Throw in a change of bike then you can save weight for when you need it.

The focus seems to be on GC riders using this technology for direct benefit, but the GC rider could benefit from having a domestique using a motor to save their legs for the next days stage. If you’re on a mountain stage and have an extra rider then you have an advantage.

Another example is sprinters. They are generally bad at getting over the mountains for two reasons – one is fast twitch muscles, and the other is saving their legs for the next day. Pop in a motor and they can have an easier day.

There is also an issue over the ethics and whether riders can justify using them. I don’t doubt they can – we already see magic spanners, and sticky bottles used in races, so why not a motor. Personally I think the UCI knows more about it than they are telling us

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.