Trek have joined the "performance road e-bike" club with the launch of the new Domane + LT.

The Domane name represents their endurance-focused range, and the new bike is no slouch in that department, with front and adjustable rear IsoSpeed damping providing neatly integrated shock absoption.

What makes this different from other Domane models is the inclusion of a motor, providing assistance on demand, to help extend your rides.

Trek are keen to emphasise that this is a proper Domane, that looks, handles and feels just like a conventional bike. The added power is simply there if you need it, and can in fact be turned off completely (and even removed) when not needed.

All the rest of the spec reads much like any other modern performance road bike, with hydraulic disc brakes, internal cable routing and, of course, clearance for up to 38mm wide tyres.

above: adjustable top-tube IsoSpeed means this should be a particularly comfortable proposition for long days in the saddle

Trek have opted for a Fazua motor system, which provides power at the cranks (rather than at the rear hub). There are pros and cons to either option, but one key advantage of a crank-based system is that you can easily swap between different wheelsets, using any standard road wheels.

The 250 Wh battery can provide assistance up to the legal limit of 20 mph (although there's nothing to stop you pedalling faster than that yourself!) and Trek quoted a range of up to 65 miles with continuous assistance (but in reality you're unlikely to have the assistance turned on all the time).

At launch Trek are offering the Domane+ LT as a complete bike, with an Ultegra mechanical groupset and the tough, well-engineered DT Swiss G1800 wheelset at an SRP of £4900. This build weighs in at 13.56 kg (29.9 lb) in a 56cm size, which is pretty impressive for an e-bike, and should make for a lively ride.

Project One configurable build options will be available early in the new year, allowing you to mix and match components to create your own unique build.

You may not always need or want the assistance, and if that's the case the entire system can be removed, effectively turning this into a regular Domane (with no real downside - Trek even include a cover so that you won't have an unsightly gap in the frame). This brings the weight of a 56cm bike down to just 10.7 kg (23.6 lb), not the lightest, but a respectable figure for an endurance bike.

above: the removeable drivepack is neatly integrated into the frameset

The controls for the assistance levels are built into the top tube, easily accessible on the go (and freeing up handlebar space for lights, GPS, etc).

Another neat touch is the integrated front and rear lighting, powered from the internal battery. Think of these as daylight running lamps, designed for visibility - they're a clever safety touch.

Geometry is in line with the rest of the Domane range, the Fazua motor is tried and tested, and IsoSpeed is a proven benefit for endurance rides.

So, on paper this looks like a very tempting proposition for anyone looking to increase their endurance range and open up new routes for exploration.

We'll be very interested to get one of these on test - look out for a full review in the new year.