The Atherton S.170E.2 won the 2026 Mountain Bike of the Year test, and it uses the Avinox M2S motor. It is a bonded aluminium frame assembled in Wales, priced at £7,999. For a lot of riders, the hype usually centers on carbon bling, but there is something to be said for a bike that actually performs on the descents without needing a carbon badge to prove its worth.
That said, the trade-off here is a shorter battery range and a heavier build compared to the carbon rivals from brands like Specialized or Yeti. I prefer practical value over overpriced gear, but range is a functional reality when you are out on the trails.
Does the superior descending performance and price justify the shorter battery range and heavier aluminium build compared to carbon rivals?
Whether that trade-off is justifiable depends on how much the added mass affects the ride feel on the climbs. While aluminum can offer impressive stiffness and value, a heavier build often shifts the balance of the bike's handling. Carbon usually allows for more precise tuning of vibration damping and weight distribution, which can reduce fatigue over long days. If the descending performance is truly superior, the weight penalty is a fair compromise; however, for most riders, the efficiency gained from a lighter frame and better compliance often outweighs the raw descending prowess of a heavier alloy build.
The idea that carbon compliance is a magic bullet for fatigue is usually just a way to justify a higher price tag. Most riders find that getting fitter by riding hills regularly does more for their endurance than saving a few hundred grams on the frame. If the alloy build handles better on the descents, that is a tangible performance gain. Weight is a fair trade-off when you are actually pushing the bike, rather than just chasing a lower number on the scale to feel faster.
Handling is a critical metric, but treating weight as a fair trade-off depends on where that mass is located. A heavier alloy build can feel planted on descents, but that same mass often translates to a more sluggish response during high-cadence efforts or steep climbs. While frame weight is rarely the deciding factor for most riders, the real distinction is usually how the material handles vibration. Carbon allows for specific tuning in the seatstays to dampen road chatter, which reduces systemic fatigue over several hours in a way that raw fitness cannot fully offset.
Claiming carbon seatstays magically stop fatigue is a stretch. For most, the vibration is handled better by picking the right tyres and keeping the pressure correct rather than spending thousands on a specific weave of carbon. If the bike is planted on the descents and the motor does the heavy lifting on the climbs, the supposed benefit of vibration damping becomes a luxury, not a necessity. It is a classic case of using technical jargon to justify a premium price tag when actual riding effort and basic gear setup provide the real results.
Tire volume is certainly the most effective way to reduce high-frequency road chatter, but that is a different mechanical function than frame compliance. While tires handle the surface noise, compliance in the seatstays and seatpost is what actually saves the lower back from systemic fatigue over a long ride. Even with a motor assisting on the climbs, the constant vibration transmitted through a stiff alloy frame still accumulates. It is less about a premium price tag and more about the trade-off between absolute stiffness and the ability to stay comfortable in the saddle for several hours.
Attributing lower back fatigue to frame stiffness is a convenient way to sell expensive carbon. In reality, staying comfortable in the saddle for hours is mostly about a proper bike fit and the rider's own conditioning. If the frame is too harsh, it's usually a sign of over-inflated tyres or a poor saddle choice, not a lack of expensive seatstay compliance. Pushing through the miles and building the strength to handle a stiff ride provides more long-term value than paying a premium for a frame that tries to do the work for you.
