Thorn Mercury review

Welcome to a very special bicycle. Thorn has been designing touring bikes from its Somerset headquarters for 25 years, and its experience really shows. The firm's range is diverse, offering 700c road wheels and 26in mtb-style wheels with Rohloff or derailleur gears. There's something for everyone.

The most intriguing for me was Thorn's flagship big-wheeled tourer, the Mercury, a Rohloff-equipped machine with drop bars. Quite an uncommon sight in the touring world, the brand new alloy shifter from Gilles Berthoud is the first of its kind to fit a drop handlebar which works with a Rohloff hub. To make it even more special, Thorn has designed the handlebar itself, making sure this bespoke item fits perfectly.

Frames come in eight different sizes, with four sizes specifically for use with a drop bar, and another four to use with a straight bar set-up giving plenty of options for even the most choosy of riders.

There are seven different front forks to choose from, each one turning the Mercury into a different style of bike. On our model, we went for the Reynolds Super Tourist steel touring fork, which gave me the option to include a very solid-looking front rack and a strong V-brake. At the back, there's an Avid disc brake to help control your speed on the big mountain descents.

Putting together your bike could be very confusing. But thanks to Thorn's spec sheet, all you have to do is give the team your measurements, tell them what parts you'd like, explain what type of riding you want to do, and the process becomes a lot simpler.

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Built to last

The Mercury needs to be seen to be appreciated. The paint job is simply wonderful. All five designs are real paint jobs, with not a sticker in sight and the finish is absolutely first-class. We went for a traditional British racing green, mixed with cream.

Very classy. Looking closer, you'll see some very nice touches. That neat alloy shifter we mentioned earlier really catches the eye. In use, it feels industrial, but I'd take that solidness over a flimsy plastic shifter any day. On the rear seatstay bridge, there's a special brake adapter, allowing you to fit a deep-drop caliper brake. With two different brake options on the rear (ours had the disc, of course), you know you're dealing with a versatile machine.

You don't often spend time admiring the underneath of a bicycle, but you will with the Mercury. Thorn has designed a special bottom bracket that it calls a mini-eccentric BB shell. I trust Thorn when it states that this saves considerable weight. The flipside is a shorter service life for your chain, as it will need to be replaced more regularly. Before this gets too complicated (with details of sprockets, rings and chain links), it will suffice to say that, as long as you replace your chain before any epic tours, your ride should be trouble-free.

By now, I'm desperate to take the Thorn out for a spin. As you probably expected, the ride matches up to the hype. It's very smooth. The wheels do their part to soften the lumps and bumps of the road. They're neither the lightest nor the fastest rolling, but they are built with strength and longevity in mind.

Taking into consideration, for the purposes for which they are intended, they are excellent. The Schwalbe Kojak tyres are chunky but slick touring tyres designed for tarmac roads. The Schwalbe Marathon, on the other two bikes, is a better compromise of off-road grip and rolling resistance, but if you're sticking to tarmac, the Kojak's ideal.

If you haven't used one, the Rohloff hub can be a bit of an unknown quantity. When compared to a cheap groupset, I can understand why you would wonder about the high price. But it's bombproof. Stories of these hubs lasting 100,000 miles without a service might be a little bit exaggerated, but it helps you understand why they are so well-loved the world over.

Satisfaction guaranteed

There are 14 gears to choose from, with a range of ratios similar to that of a mountain bike triple. What's great is the ability to completely change the gear while stationary - a perk if you stop mid-ride and forget to change down to an easier gear.

It can take up to 1,000 miles just to wear in, so I'll be forgiving to the brand new one on the Thorn, which was a little bit noisy in a few gears. Once up and running, the shifting is fairly quick, though not as instant as the Koga's Deore XT set-up. But then you could argue that what's lost in terms of performance is easily countered by the long term benefits of such minimal maintenance.