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1961 Triumph T120 Bonneville
By 1961, Triumph had refined their ultimate classic bike to near-perfection. Rod Eady's T120 is a concours champ... Although there are some people who prefer the very first version of Triumph's T120 Bonneville, introduced in 1959, most riders are very happy to pay a little bit less for the 1960-onward models which benefited from a couple of years of further development and use a duplex frame. This swinging arm chassis went a long way towards taming the Triumph twin's infamous steering instability under pressure, associated with the earlier single downtube frame. Rod Eady is just such an owner - you're looking at his 1961 T120 Bonneville which took home an RC concours award at the NEC Classic Motor Show last autumn. 
1961 Triumph T120 Bonneville
The Bonneville was a 650cc development of Turner's twin which could trace its lineage straight back to the Speed Twin of 1937. The T120 was essentially a twin-carb version of the tigerish T110 650, equipped with a light alloy splayed-port cylinder head and twin, filterless Amal Monobloc carbs, running a higher compression ratio and tweaked cams. These modifications gave the Bonnie around 46bhp at 6500rpm and a realistic top speed of 110mph -- not much different to its single-carb counterpart, but the T120 was quicker getting there. American riders paid more attention to standing quarter mile times then outright terminal velocity - and the Bonnie was built for the USA. The T120 was stopped by an eight-inch brake in a full width front hub, and it tipped the scales at just over 400lb. 
1961 Triumph T120 Bonneville
Initial machines were styled rather stolidly but the 1960-on T120 swapped the traditional British nacelle for a more sporting, shiny chrome headlamp - and this also meant that a rev counter could be fitted as an optional extra, for twin-clock kudos. 1960 models also benefited from slimmed-down mudguards and improved forks, flatter handlebars and tighter steering. The bike's wheelbase had reduced slightly which made it light on its feet on the street, although the new chassis didn't offer a whole lot of ground clearance so it was easy to produce a shower of sparks on left-hand bends. The major weakness of the 1960/61 Bonnie was in the electrical dept; a chorus of complaints occurred about the variable voltage regulation, failing switches, poor quality wiring, batteries fractured by vibration and so on. In fact the new frame did produce quite harsh vibration - the rider was reasonably well insulated from its effects but the components bore the brunt of the damage. The chrome tank retaining strap, for instance, had to be replaced with a steel item for 1961. There were other upgrades for that year, too, including an improved gearbox with needle roller bearings, a folding kickstart, fatter rear tyre and an enhanced brake operating mechanism which made the Bonnie's stopper one of the best of its time (although these days it would still feel spongy in short order if applied to its maximum for a sustained period). 
Rod and his 1961 Triumph T120 Bonneville
The result was a well-developed, decently rapid sports roadster which was pleasant to use every day but which could unleash sprightly performance when the road ahead was clear. The duplex frame all but eliminated the hinged-in-the-middle sensation, although the rear wheel did still move around somewhat on fast corners. Vibration was obvious to the rider at engine speeds over 4000rpm and if you were chasing maximum power at 6500rpm then things got quite harsh. Some owners also struggled to keep both carbs satisfactorily synchronised - although for many the charismatic looks of the T120 Bonnie more than compensated for that hassle… This iconic motorcycle stayed in production for only a few years before development of the breed saw the unit-construction T120 take over from 1963. So Rod's 1961 bike is an extremely desirable machine - perhaps the most useable and well developed version of the pre-unit Bonneville. Rod bought his Bonnie in 1994, complete but in need of restoration. Since then it has been totally restored to bring it up to the sparkling, show-winning condition you see here. Rod took on the whole project and stripped the Bonnie down to component parts, then painstakingly put it all back together again - with some help from the experts at Ace Classics. 'I recommend Cliff and Kevin at Ace; it could not have looked like this without their help. Steve at Northants Classic Bikes supplied many parts too, and was a very good agony aunt!' 
Rod's 1961 Triumph T120 Bonneville on show at the NEC Classic Motor Show
This bike was rebuilt to original specification and has rewarded Rod's efforts by performing faultlessly ever since. It collected a well-deserved RealClassic award in autumn 2008 at the NEC Motor Show. Rod heartily encourages anyone thinking of buying a similar bike to take the plunge. 'Just do it' he says; 'you'll love it!' --------------------
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