Thunderbird: A Britbike on steroids

First, a quick history lesson: When Edward Turner introduced the 500cc Triumph Speed Twin in 1938 it was with the stated intentioned of proving that a parallel twin could be more compact, lighter and quicker than a single of comparable capacity - which it was.

Then, when he built the Thunderbird in 1949, it was to show size-obsessed Americans that a 649cc, OHV parallel twin could run rings around side-valve V-twins of nearly double its size - which it did.

What he would think of the current Thunderbird I don't know.

It has a fairly conservative, parallel-twin engine with vertical cylinders, a short, stiff crankshaft and a three-axis gearbox - but on a truly Herculean scale. Bore and stroke are 103.8 x 94.3mm (about as big as a 500g can of instant coffee) for a total of 1597cc (yes, Cyril, 1.6 litres) and the engine alone stands an imposing 540mm tall.

It's fed by two relatively small throttle bodies with progressive throttle linkages, which means that small wrist movements just off idle give gentle, easily modulated acceleration while the same movement anywhere near the top of the twistgrip travel will deliver explosive results.

Triumph quotes 62.kW at 4850rpm and a stump-pulling 146Nm at only 2750rpm.

In real terms the Thunderbird pulls like a locomotive from about 1600 revs; give it a handful anywhere above 2500 - in any gear - and you'll be hanging on for dear life as this bike bends the laws of physics, seemingly at will.

Bearing in mind that Hinckley's monstrous twin weighs 339kg with a full tank, its acceleration is awe-inspiring and, in confined circumstances, frankly intimidating. Wait until you've got a lot of open road in front of you before you yank this thing's tail in earnest.

Even in the tallest of its six gears it'll catapult you from 60 to 150km/h in about as long as it takes to draw one deep breath, and then slowly build momentum as long as your upper-body strength holds out.

By putting my feet on the rear 'pegs and leaning well forward I pulled a terminal 184km/h (true speed) at the end of a long, long run, with a needle's width less than 200 on the speedometer and a little more than 5000rpm on the rev-counter.

Neither gauge is easily legible and the rev-counter in particular has an uneven arc, hence the vague figures. What's not vague at all, however, is the fuel-consumption figure, a wallet-pounding 8.8 litres/100km across an even mix of commuting, country cruising and performance testing.

That figure prompted a squeal from the supplier, who said he was using less than six litres/100km cruising around town on the same bike - which goes to show that fuel consumption is largely dependent on riding style.

The crankpins are set at 270 degrees for that all-American, rumbling soundtrack and there are some very large bits of metal thumping about inside this industrial-strength prime mover so, despite Triumph's ever-present balance shafts, a fair amount of secondary vibration makes its way itself felt through the handlebars and footpegs.

However, that not only adds character, it's also a good tactile reference for when to change gears - certainly safer than taking a long look down at your crotch in heavy traffic.

The rest of the drive-train is pure Hinckley: the clutch is robust and predictable, although without the final, rock solid take-up that makes Kawasaki clutches, for instance, so great off the line, while the gearbox (why six, for heaven's sake, four would have been more than enough!) is firm, positive and vocal - all of which is both expected and desirable in a transmission that has to handle this much torque.

The gearbox is slick enough, and the progressive throttle control precise enough, for seamless upshifts without the clutch from second onward but, in deference to the bike's phenomenal engine braking, I didn't try any clutchless downshifts.

Final drive is by toothed belt, which is clean, reliable, low-maintenance and obviates the need for a rear cush drive.

Any bike this heavy and with this much acceleration had better have decent brakes; the Thunderbird is blessed with four-pot Nissin callipers in front and a Brembo twin-piston sliding calliper at the rear. The front brakes in particular are immensely powerful and beautifully modulated; it is in fact the front tyre that is the limiting factor.

I never felt the (standard) ABS cut in, even when riding on wet roads, so I deliberately stomped on the rear brake on a straight dry road, just to feel the familiar pulsing under my right boot and cofirm that it was working - which it was.

The chassis and styling are a slightly uneasy mix of (very large) retro Britbike and power cruiser. The tubular-steel, double-backbone frame has all the flexibility of the Great Pyramid of Cheops, top-drawer 47mm Showa forks keep the front end in line and there is no external plumbing - but the speedometer is on the 22-litre fuel tank, the footpegs are way out front and rear suspension movement is very limited and thus a little choppy.

The speedo, by the way, has an LCD screen at three o'clock and an “i” button on the right switchgear that lets you scroll through a clock, odometer, two trip-meters and a range-to-empty readout, but the displays are small and a long way off the rider's eye-line - don't fiddle with them in traffic.

The faux-billet wheels are almost (but not quite!) too chunky for the rest of the styling, while a V-Rod-style rear mudguard is a necessity for the same reason as on the V-Rod - a humungous 200/50 rear gumball. A 1615mm wheelbase lends a lot of straightline stability while a low centre of gravity and perfect balance (plus wide 'bars for leverage) make the steering light if still a little slow.

Whether in tight corners or peeling into long sweepers, you're always conscious that there's a lot of motorcycle under you, but the Thunderbird is never hard work to ride, even in traffic.

It handled our ride and handling track with aplomb at a (very respectable for a cruiser) average of about 120km/h gently scraping the hero blobs on both sides once I'd passed the apex, got into the groove and turned up the wick - and, with all that torque on tap, you can come out of any corner hard enough to surprise your sportster-riding buddies.

The test bike had the optional “touring” dualseat, a vast improvement in comfort over the standard single ploughshare and pillion pad; I opted to do without the quick-detachable “barn-door” screen but retained the sissy-bar.

The screen, seat and sissy make up an accessory pack that's included in the R169 500 price tag.

VERDICT

Despite its Native American name (the thunderbird was a mythical beast that shot lightning from its eyes and pulled the clouds together with the beat of its wings to create thunderclaps) Hinckley's biggest twin is a distinctively British power cruiser that rides and handles better than most, aptly living up to the Triumph slogan “Go your own way”.

Price: R169 500.

Bike from Mike Hopkins Motorcycles, Cape Town.

SPECIFICATIONS

Engine: 1597cc liquid-cooled parallel twin.

Bore x stroke: 103.8 x 94.3mm.

Compression ratio: 9.7:1.

Valvegear: DOHC with four overhead valves per cylinder.

Power: 63kW at 4850rpm.

Torque: 146Nm at 2750rpm.

Induction: Multipoint electronic fuel-injection with progressive throttle linkage.

Ignition: Digital electronic.

Starting: Electric.