|
|||||
BMW goes radical with its quickest Boxer twin yet April 4, 2006
By Dave Abrahams It had to happen: BMW has fitted the engine of its R1200 GS Gelandescooter to the chassis of the R1100 S sports bike to create the quickest, most rideable, Boxer twin yet.
It breathes in through 52mm VDO throttle bodies with special eccentric throttle cable pulleys whose diameter grows towards the open end; throttle response is no longer linear. Unfortunately this has dialled in a distinct flat spot just as the engine comes on cam at about 7000rpm; it's no more than a barely-felt hesitation on the road but is disconcerting on the track which, BMW wisely felt, was the best place for the media scribes at the world launch to explore the performance potential of its hottest twin yet.
Only once, however, did it induce a mild headshake as I exited the double-apex turn four of Cape Town's Killarney circuit, pretty well wide open in fourth (the fast guys go through there flat out in fifth!) and never so much as a twitch, but it's a bit off-putting until you get used to it. Once past the flat spot the engine pulls strongly, vibrating like an electro-massage machine, way past its power peak to hit the rev-limiter in top with 250+ on the analogue speedometer. The chassis' most composed cruising speed of 160km/h unfortunately coincides with a particularly nasty vibration but the engine runs turbine-smooth at a slightly lazier 140 – maybe the law-abiding folks at BMW are trying to tell us something. The folks also say the bike should return about 5.6 litres/100km at a steady120km/h; around the mountains of the Boland the bikes all went on to reserve at around 150-160km, which translates to 8.8 litres/100km. Slightly grabby The clutch, gearbox and final drive are as per the R1200 GS but the combination of a slightly grabby single-plate clutch and non-linear throttle response meant smooth gear-changes took a bit of practice. Thanks to the traditional noisy BMW first-second movement I was never able to get a decent shift off the line but by the end of the launch ride I was pulling clutchless upshifts from third to sixth – which says a lot for any shaft-drive transmission. The steering-head angle of the R1200 S is one degree steeper than that of the R1100 S at 24 and castor has been reduced from 100 to 87mm, although the longer, single-sided swing-arm means its wheelbase has increased by 9mm to 1487mm. Superbly stable front The front A-arm is now an alloy casting rather than a tubular-steel fabrication, saving a couple of kilograms as well as reducing suspension inertia; 41mm stanchions and an adjustable central shock-absorber combine for a superbly stable front end that never seems to get out of shape while its geometry confers a degree of anti-dive that lets you brake harder than you'd believe possible. A shaft has more unsprung weight than any other final drive but the big piggy-back Ohlins monoshock copes admirably, although the (optional) ABS can be fooled into backing off on the brakes on a really bumpy entry as the back wheel begins to chatter – which is why we were advised to switch it off for track riding. Ohlins suspension and a 6" rear rim mounting a 190/50 rear gumball are factory options for the R1200 S on the world market; all South African-market examples will be fited with these as standard. ABS and heated grips will however, be extra-cost options. Car drivers are often surprised to hear that ABS is not always the optimum solution for motorcycle braking, for the same reason that bikes have separate controls for their front and rear brakes – the braking requirements for front and rear wheels vary under different circumstances. On this bike BMW has dispensed with the electrically power-assisted brakes of its big tourers, as much for immediate, accurately modulated effect as to shed weight. All the hoses are braided stainless-steel and the big four-pot Brembo callipers on 320mm discs (up from 305mm but 0.5mm thinner at 4.5mm to save weight) work superbly. Sunday morning hooligan tool Its ability to brake hard, deep into corners, without the chassis losing its composure is one of this bike's best features and would make it an eminently satisfactory Sunday morning hooligan tool - if you've never out-braked your mates into a corner this bike will teach you how. Its handling seems a little slow at first, as if the designers have dialled in a little extra stability to reassure the born-again bikers at whom this machine is unashamedly aimed. But the faster you go the quicker it gets; if you want you can dive down the outside of a corner on the brakes and throw it on its ear, Grand Prix style; with a little muscle and some body English the bike will turn in harder than any 190kg streetster has a right to. Like any shaft drive bike, however, the R1200 S likes to drive through a corner with the power on; get on the gas as early as you can, hold a steady throttle until the apex then crack it on - you'll come out hard, with the suspension loaded and the chassis well settled. It's a good feeling. BMW insists that this is its sportiest bike yet but it's surprisingly comfortable; the footpegs are right under the nose of the saddle for perfect body balance, while the "clip-on" handlebars are higher than they look and didn't strain my wrists in two hours of riding, including a slow, cautious traverse of Franschhoek pass in the wet. Standard BMW switches The switches are standard BMW issue, which has been relentlessly criticised by motojournos since day one, but which Beem owners say becomes second nature after a while. The instruments have a small, oval rev-counter above a bigger, analogue speedometer (once again aimed at older riders) with a comprehensive LCD display to the right, including a range countdown that automatically replaces the trip meter when you go on to reserve – a powerful incentive to back off and head for the nearest petrol station! This is not a superbike; for that it would need 30kg less weight and 30kW more urge. It is, however, a superbly composed sports-tourer of proven design and matchless build quality. The chassis is so composed that the package would be a little bland were it not for the engine's small idiosyncracies – and its totally unexpected top-end rush, made more sudden by that little fuelling glitch. If you thought Boxers were short on Grin Factor, think again. The R1200 S will be released in South Africa in August 2006 at R112 500. Go take a look. |
