Aussie Exclusive – BMW HP4 Race | Bike Tests | Latest Tests
Carbon fibre was too expensive, they said, too stiff, too difficult to use extensively in production motorcycles. With the HP4 Race, BMW proves them oh-so wrong...
For more than three decades, BMW has been at the forefront of two-wheeled innovation: ABS, Telelever, Paralever, Duolever, C-evolution, the K100/ K75 ‘Flying Brick’… And with the BMW HP4 Race the German company has done it again, by pushing the bounds of what can be done with carbon fibre. Just 750 examples of this exotic new model will be built, 10 are headed for Australia, each with a retail price of $114,500.
BMW’s automotive division has become adept at volume manufacture of carbon fibre components thanks to its i3 electric car. Now BMW Motorrad has adapted the Resin Transfer Moulding (RTM) manufacturing used for that vehicle to two wheels, thus becoming the first motorcycle manufacturer in the world to develop a conventional twin-spar frame made entirely of carbon fibre. And thanks to RTM, it’s feasible to construct on a volume production basis, with each frame identical.
The HP4 Race is in effect a revival of the HP4 high-end streetbike introduced in 2012 and sold for three short years, before it was replaced in 2015 by the current generation S1000RR – with some key differences. First, the new bike is available only in track-ready guise, i.e. it is not homologated for street use. Second, it boasts a more powerful version of the engine used by Jordi Torres in the 2017 WSBK series. And third, this bike is incredibly light. While Jordi’s BMW Superbike tips the scales at 168kg with oil and water but no fuel, the carbon-framed HP4 Race I rode around the Estoril Circuit in Portugal weighed in at just 146kg dry, or 171kg track ready and fully fuelled.
Key elements in that weight saving are the carbon fibre frame, subframe and wheels. The chassis, meanwhile, weighs a mere 7.8kg complete with bulkhead partitions and metal inserts, which are bonded into it at the manufacturing stage for long-term durability. That’s a huge 4kg lighter than the S1000RR’s cast aluminium chassis, and the carbon fibre frame is moreover a one-piece hollow monocoque construction made from a single piece of material, and thus has no seams, no joints, and no neuralgic weak points, such as individually bonded or bolted-on components. Yet according to project manager Christian Gonschor, it does indeed have a degree of controlled flex engineered in at design stage, to deliver the critical responsiveness and dynamic feedback that an over-stiff chassis doesn’t convey.
The self-supporting seat subframe is also made using RTM, and is adjustable for three different heights varying in 15mm increments from 816mm to 846mm, while the milled aluminium footrests are also eight-way adjustable for position. You can’t not get comfortable in it. The wheels are 30 per cent lighter than conventional forged aluminium ones, and offer a significant 40 per cent reduction in gyroscopic weight, which translates into much improved steering, plus enhanced acceleration and braking. That’s because there’s less rotational inertia, thus helping improve acceleration as well as braking, with less overall weight to stop and start.
Read the full story in the current issue of AMCN on sale now!