To the ride impressions. It's going to be necessary here to distinguish elements that might be true of many options from elements specific to the Mercury 650b but I'll do my best.
For background, I cycled a lot in my teens, although not with a club or in organised events. At around the age of 16 I picked up a bargain bike used with nice lugs and possibly a butted reynolds frame, though it wasn't labelled. Came with tubulars and a single chainring, and I fitted a touring triple and 5-speed touring rear cluster. Lovely soft ride - in fact the fork was a bit wimpy torsionally. Managed a fun multi-day tour on it then swapped it for a new Peugeot PX10LE, with 531 tubing and again tubulars, to which I fitted the touring chainset and cluster. This was much stiffer and not nearly as comfortable, which surprised me at the time. That bike was stolen about the time I turned 20, and given I had got heavily into motorbikes it took me nearly 20 years to replace it.
The replacement was a Trek 7900 multi-track hybrid, with a steel unicrown low-rider fork, lugged and glued carbon-tube main triangle and quite heavy aluminium rear triangle that could handle panniers. The base weight was 11kg with seat and oedals, and as I picked it up heavily discounted I was prepared to accept a frame size way too small but with a top tube very long for its size. Came with Shimano XT MTB derailleurs. Used it over the next couple of decades as a mountain bike (there was enough clearance for 700x38c knobbies), commuter and multi-day tourer. The fit was never quite right but it did the job and rode quite nicely. Key limitation was torsional stiffness, which exhibited through the steering when loaded. Geometry I now recognise as randonneur - so I might have done better to bias loads to the front. Steering unladen was overly light and not terribly accurate.
For some reason after a driveline refurbish it started throwing its chain, and eventually a too hasty retrieval left a nasty gouge in the chainside stay. It's probably not weakened the stay a lot, since the aluminium seems quite thick at this point, but I wouldn't take it touring. Having decided it was time I got back into riding for fitness, I did a lot of research and purchased a Mercury - hence this review.
The first thing to say about the Mercury, a 61s with flat narrow bars, is that it fits me beautifully. Even though the seatpost as supplied by Thorn was adjusted way too high - I could barely get my toes on the pedals. Nevertheless I had asked for a fairly relaxed riding position, and with the seat readjusted that is what I have, with the 'bars set as supplied.
The fit alone seems almost wirth the price of entry. From the saddle, the bike feels very different from how it looks side-on. It looks like a big bike, but from the rider perspective it feels very compact, helped by the moderately steep (for a tourer) head tube angle and that fat 50mm Schwalbe G-One Speed tyre. I persistently experience it as a sport-tourer - just as Thorn claims it is. The long steerer tube with its spacers disappears as you're virwing it vertically, and overall I feel like I'm riding the cycling equivalent of a GT car - not light but small, sharp and comfortable.
I also enjoy looking down at the finely crafted lugged fork - so much nicer aesthetically than the unicrown fork that was fitted to the Trek and seems to have become the industry standard for steel.
Weight BTW on my luggage scale comes in at 13.8kg. That's with a Tubus Vega rack, full mudguards, dynohub, Edelux headlamp, Brooks Professional saddle, full-cage MTB pedals, and three bottle cages. Weight could be saved, at a price, from replacing the solid Thorn crank arms, the pedals, and the seat. I'm very comfortable with the weight, having expected that with the big frame and touring fork and the accessories and the 550g tyres it would have come in at mid-14kg. Then again, maybe my cheap scale is not all that accurate.
The ride quality is excellent, even if I thought I might have had a wee bit more compliance from the rear triangle. In that respect it feels roughly the same as the Trek, allowing for tyre differences. The fork is the Reynolds ST rim-brake verson with low-rider lugs, and with the big tyres comfort at the front is superb. You can feel the blades soaking up road hum in high speed descents - so on the question whether a steel fork actually does flex helpfully I'm a believer. The fork feels noticeably better than the steel Trek fork, and at the same time feels much more rigid torsionally. Forum regular PH has compared this fork with the alternative 853 fork on his Mercuries and says the ST fork is significantly less compliant. The 853 fork must be wonderful, but with the big tyre the ST fork is really, really good.
Andy Blance talks up Thorn handling, and from my experience so far he is well justified. It's great in a 'just right' sort of way - neither too twitchy nor too slow. On my regular ride there is a very steep brief climb up from a bridge underpass to road level, which includes an extremely tight left and right ess. I cleaned it once on the Trek but negotiating the left turn was so marginal that I walked it every susequent time. Helped enormously by the very low gearing I have for the Rohloff, the Mercury makes that turn feel safe and easy. It's the same in the way down: on the Trek I would unclip from the pedals in case I needed to dab; on the Mercury I've remained clipped in and felt safe. Likely the rigidity helps greatly here too.
Mid-speed handling in turns is helped greatly by those grippy, wide tyres, and the Merc carries momentum beautifully through twists and turns tyical of local cycling paths.
But it has been on the few occasions I've been able to enjoy winding high-speed descents that the Merc really shines. Here the rigidity, balance and accuracy of the rolling chassis has felt magnificent. I've done too few of these to say much more, except to observe that the exhilaration of a quick descent is enhanced very significantly by the confidence I have felt from the saddle. This was one of the less happy elements of handling on the Trek, so the difference feels very pronounced. It feels like on the Mercury I am going only half as fast on the downhills, except that I know I am not and quite likely I'm quicker.
The final touch on the handling comes from the tyres. The security added over the Schwalbe Kojac 700x35c slicks on the Trek is profound. Its particularly valuable on slick-looking surfaces but it's there all the time. You get used to accommodating the uncertain road grip of narrow rubber, but there's stress involved and I hadn't realised how much until I rode these big G-One balloons on winter trails.
Next: the Rohloff and other bits and pieces.