Skarpers unique click-on/click-off ebike system has made it easier and cheaper to convert multiple non-assisted bikes to ebikes and now the company is developing a mountain bike version with Red Bull. Since the company was founded in 2021, a mountain bike version of the motor system that drives the rear wheel via a special disc rotor/planetary gearbox has been in the plans. I was highly impressed by the existing road and gravel Skarper kit when I reviewed it, and what I spotted at the MK-7 launch event hints at where this platform could go next. Read more: You can now buy Ribble bikes with Skarper's ebike conversion kit Why build an MTB version? The prototype is compact, and Skarper promises the final version will be smaller still. Warren Rossiter / OurMedia The road and gravel Skarper kit is restrained capped to meet UK/EU pedal-assist regulations and ensure it's legal to use on the road. However, Red Bull Advanced Technologies wanted to see what else the platform coulddo. The MTB project posed an engineering challenge: how much power can you push through the system? How robust can you make it? And how do you handle the chaos of mountain bike riding? Sources close to the project described the prototype as "a beast" and, having seen it in person, I'm inclined to agree. The challenges around a Skarper drive system for mountain bikes are many. For one, there's the higher torque required for off-road riding, while keeping the unit compact. That's not to mention the myriad back-end designs across mountain bikes, from hardtails to multi-linkage suspension. From the earliest incarnations of the mountain bike project, Skarper has worked in tandem with Red Bull Advanced Technologies. The aim is to create a design thats compatible with as many different bikes as possible. Skarper set out to construct a motor and gearbox capable of producing the required power and torque, while remaining compact enough to be unobtrusive on the trails, yet stable enough to handle the rigours of off-road riding. Early prototype breaks cover The mule bike has a lot of control and monitoring systems. It also looks as though the mountain bike version will get on-bar controls. Warren Rossiter / OurMedia What we see here is an early mule prototype produced with Red Bull. It follows the same design choices as the road-going Skarper, with a self-contained motor and gearbox driving a disc rotor with built-in planetary gearing. Skarper and Red Bull are remaining tight-lipped about the exact details of the unit. However, the main unit has an innovative two-speed gearbox that works in conjunction with the system's brain, including an inclinometer. Like the road-going Skarper, the mountain bike version drives the bike through a special disc rotor. Warren Rossiter / OurMedia One of the quirks of this early prototype is the ability for it to regulate power on an incline in tandem with your pedalling. Or, as early test rides have shown, give your bike the ability to hold a wheely indefinitely, motocross-style. However, I doubt that will make it into the final production model. What this prototype reveals is something important about the underlying technology: the capability of the DiskDrive platform can match current mid-drive and hub systems, with the Red Bull engineers confident it can surpass current eMTB rivals. Skarper also told me this prototype is much larger than the final unit will be; this is a model to provide proof of concept. The next stage will be around optimising the technology and making the unit as compact as possible without compromising on power. The monitoring systems on the top tube are for evaluation purposes, although I spotted what appear to be on-bar controls rather than the app control used on the road-going Skarper. I asked Skarper for comment and it said: "Skarper represents the arrival of the 'Third Drive System' a patented technology platform that offers a modular, high-performance alternative to traditional ebike integration. The fact that six leading British bike brands have already committed to the platform for their 2026 bike line-ups is significant validation of our engineering and the click-on category we are building. "Our current focus remains on delivering the best possible experience for road and gravel cyclists, ensuring that power never comes at the cost of ride feel. While Skarper does not comment on unannounced products or future roadmaps at this time, we are always interested in exploring opportunities with the right partners to bring future products to our platform." Read more: How to convert a bike to electric power: electric bike conversion kits explained A huge challenge The prototype drive unit is fitted to a Cannondale Habit. Warren Rossiter / OurMedia Its still early days on the project, which is a huge challenge for Skarper and Red Bull Advanced Technologies. However, if they get it right, having a mountain bike thats only electric when you want it to be could be a game-changer. It could help establish Skarper as not a single-product outfit but an electric motor platform provider and an established third way: mid drive (Bosch/Shimano/TQ/Avinox), hub drive (Mahle) and disc drive (Skarper). Skarper's original DiskDrive impressed us; we can't wait to see how the mountain bike version shapes up. Russell Burton / Our Media Could Britains Skarper soon be a challenger to more established electric bike motor providers such as Bosch, Shimano, TQ and Mahle, as DJI has done with the Avinox? Watch this space.