Koga are a big name over on the continent and they’re well known for their city and touring bikes, although they make everything from racers to mountain bikes. The E-Xtension is the base model in their electric bike range and prices start at £1,849.
Koga are unusual in that they offer each bike with a range of batteries. The E-Xtension can be supplied with four different batteries, anything from a 317Wh battery (that’s the one you get at the base price, of course) all the way up to an enormous 622Wh which in Eco mode Koga reckon will transport you not that far shy of 200km. Given hills, and wind, and the fact that no-one rides around in Eco mode the whole time, you’ll be well short of that. But if you’re looking for a bike for longer excursions or you have a sizeable commute, this is about the biggest battery that’s currently a stock option.
Batteries up to a whopping 622Wh are available
Koga use their own system, ION, which is a rear-mounted wheel motor. Different bikes use different battery configurations but here the battery is in the rear rack. The blue-backlit ION head unit is removeable and the system won’t work without it, so that’s a useful theft deterrent, as is the nurse’s lock on the rear wheel. All the bike’s functions are controlled from a remote that sits next to the grip.
The frame and fork are both aluminium alloy, with smoothed welding for a clean look. The fork uses Koga’s Feathershock system which adds a bit of damping without the extra flex and weight you get from most telescopic suspension forks designed for the road. You get an adjustable stem to tweak your ride position.
The transmission is a dependable Shimano Deore derailleur setup, with a triple chainring and 10-speed cassette giving a broad range of gears. Mudguards, lights and a single kickstand are all included, although a chainguard isn’t.
Koga's ION display is easy to read
Dave says: The big news here is probably the battery: over 600Wh is a prodigious capacity and means that 100km+ rides are easily achievable. Koga are also very sensible in realising that not everyone needs that kind of capacity – I certainly don’t – and offering the bike with four different battery sizes is something it’d be good to see other manufacturers picking up on.
The E-Xtension is a really comfy bike to ride. It doesn’t have a suspension seatpost but I don’t find they add much over the bump-taming properties of decent-sized tyres, and Schwalbe’s 37mm Energiser tyres used here are very good. The saddle is wide and well-padded but not mushy. Up the front the Feathershock suspension works really well: it’s a much better solution than mountain-bike-style telescopic forks, which are gerenally a bit flexy and add a good deal of weight. There’s no lockout but you don’t need one, as the 40mm travel just takes the edge off potholes and the like, without ever feeling like it dives under braking. The super-comfy handlebar grips also deserve a mention.
The rear hub motor is really quiet
Koga market their ION system as silent, and certainly it’s one of the quieter ones out there. When you’re out on your own on quiet country lanes you can hear it humming to itself, but in city traffic you’d never hear it. With five power modes there’s plenty of options, but the Koga doesn’t feel quite as eager as some bikes away from the lights or when climbing, even on the highest power setting. It’s not that it’s underpowered, the 40Nm torque from the hub motor is similar to many other systems. It’s more about the way it’s applied. It’s a very smooth power transfer though, meaning that it’s easy to get used to, and to live with. There’s very little unevenness in the power curve.
As an everyday city e-bike the Koga would be easy to live with. You’d probably want to fit a chainguard to save your trousers/skirt if you’re cycling in work clothes but other than that you have everything you need here, and if you’re planning longer leisure or touring rides then the big battery options and the wide gear range, along with luggage space at the back, make it an ideal choice.