For more than three decades BMW has consistently been at the forefront of delivering innovative engineering on two wheels. ABS, Telelever, Paralever, Duolever and so much more. But with the debut of the BMW HP4 RACE it’s turning its attention to carbon fibre.
Just 750 examples of this exotic new model will be built, each individually numbered version costing Euro 80,000. It’s available only in track-ready guise painted in BMW’s Motorsport colours, so not homologated for street use. And yes – there are still apparently some not yet spoken for. Hurry, hurry….
BMW’s automotive division has already become adept at volume manufacture of carbon fibre components, beginning with its i3 electric ca. Up to the end of last year more than 65,000 units had been sold since deliveries began in November 2013. This, like BMW’s exotic plug-in hybrid i8 sports car, employs a light and resilient carbon fibre frame.
BMW Motorrad has now adapted the Resin Transfer Moulding (RTM) manufacturing system entailed in creating the i3 to a two-wheeled application. In doing so becoming the first motorcycle manufacturer in the world to develop a conventional twin-spar frame made entirely of carbon fibre. Thanks to RTM it’s feasible to construct the chassis on a volume production basis, with each frame made identical one to another.
“The industrially produced carbon fibre frame of the new HP4 RACE opens a whole new chapter in motorcycle chassis construction,” says Christian Gonschor, Project Manager for the HP4 RACE. “In it we are bringing together optimum technical qualities, consistent manufacturing quality and [economic affordability] for the first time.”
That’s because the RTM system no longer requires each CF component to be baked for anything up to 30 hours in a pressurised autoclave oven, reducing manufacturing time to minutes rather than hours. It’s much less labour intensive because instead of patiently layering up CF sheeting by hand the RTM process uses ready-shaped CF felt that’s laid into a mould then injected with resin.
The track-focused BMW HP4 RACE is powered by a more powerful 215-bhp version of the S1000RR Superbike motor. It’s similar to the one used by Jordi Torres to lead Race 2 at the Misano round of the 2017 World Superbike series for so many laps just four days before I was invited to ride the BMW HP4 RACE at Portugal’s Estoril GP circuit, outside Lisbon. Even with an identical engine, Jordi’s Superbike is heavier than the carbon-framed BMW HP4 RACE, which scales an amazing 146kg dry, or 171kg track-ready with its 17.5-litre aluminium fuel tank fully fuelled – compared to the racer’s 168kg with oil/water, but no fuel.
Key elements in that weight saving are the CF frame, subframe and wheels. The chassis is 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 4kg lighter than the S1000RR’s cast aluminium chassis. The CF frame is a one-piece hollow construction with no seams, no joints and no weak points such as individually bonded or bolted-on components. According to 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 CF seat subframe is also made via RTM. It’s 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 fail to get comfortable in it. The CF wheels are 30% lighter than conventional forged aluminium ones, and offer a significant 40% reduction in gyroscopic weight, which translates into much improved steering, acceleration and braking. Interestingly, carbon didn’t extend to the BMW HP4 RACE swingarm, which is still made of aluminium. “By the time we’d inserted all the metal fixtures we needed to incorporate in the swingarm, there wasn’t sufficient material left to justify making it in carbon fibre,” says Gonschor. “So we didn’t!”
I rode the factory S1000RR Superbike each year that BMW contested the World Superbike series, the last time at Imola in 2013 on Chaz Davies’ GoldBet bike. My first lap of Estoril on the BMW HP4 RACE was like shaking hands with an old friend you hadn’t seen for a while. It’s that close to the racer in feel and performance.
Even though the WSBK rules have been tightened up since then to bring bikes closer to stock, the BMW HP4 RACE has the same explosive, irresistible acceleration and heaps of straight line performance that Chaz’s S1000RR Superbike had. With peak power of 215 bhp at 13,900 rpm, and maximum torque of 120Nm delivered at 10,000 revs, this engine is a considerable step up from the 193-bhp HP4 that debuted five years ago. It’s easily the most powerful BMW motorcycle ever offered for customer purchase.
The rev-limiter has been raised an extra 300 revs to 14,500 rpm, and as I found each lap I’d exit the fast, third-gear sweeper leading on to the Estoril main straight, it pays to rev the BMW engine out to the limiter. So you can ignore the array of flashing red lights across the top of the 2D dash telling you to hit another gear until just before the RBW throttle stops building power. Then tap the sweet-action race-pattern gearshift to hit fourth gear as you start to straighten up and fly right down that long, long front straight.
The power is delivered in a linear, usable way, coupled with an unlikely degree of flexibility. That’s thanks to the variable length intake system, revised intake and exhaust camshafts, and closed-up gear ratios. Unlike the Ducati 1299 Superleggera it can’t help but be compared with, this isn’t a street bike, so there’s no need for a street-friendly low first gear. First and second are lengthened, there’s the same third-gear ratio as before, and a lower top three. The flawless gearshift has a powershifter and auto-blipper for clutchless downshifts, so you don’t ever have to use the clutch lever again after you’ve moved away. This all makes riding the BMW HP4 RACE a thrilling experience even before taking into account the benefits of all those missing kilos wafted away by the extensive use of carbon fibre.
No more thrilling than when you have to stop hard for the second-gear right-hander at the end of the main straight at Estoril from flat out in fifth gear and have to start flirting with the 200-metre board at speeds well over 280kmh. Each lap I tried to be a little braver and eke out an extra metre or two, five even, exploiting the phenomenal braking potential of the Brembo GP4PR calipers with titanium pistons that are de rigueur for most of the field in both MotoGP and WSBK grids.
These are easily the most effective brakes I’ve ever experienced on a production motorcycle, and yet they’re easy to modulate in slower bends if you want to just ease off a little velocity because you got over-ambitious with maintaining turn speed. By working the easily-understood button pads on either handlebar to dial in a little more of the 15-stage engine braking that can be varied for each gear ratio, I was able to get some extra help from the motor in slowing down without creating any instability. Nice.
Also 15-stage programmable is the BMW HP4 RACE’s DTC/traction control. It literally speaks to you via an audible staccato chatter as it intervenes by cutting the ignition via cylinder suppression patterns of varying strength, depending on the degree of rear wheel slip. The Intermediate riding mode I started with out of the four available (Wet, Intermediate, Dry1, Dry2) had the TC cutting in very frequently, even with the grippy SC2 compound chosen for the Pirelli Diablo Superbike Slick tyres fitted. Moving to Dry1 was much more rational, though once again you can fine tune the settings for each gear in each of the four modes. Same thing for BMW’s programmable Wheelie Control, while the other electronic features include Launch Control and a Pit Lane speed limiter. Also MotoGP/WSBK derived are the 43mm Öhlins FGR300 upside-down fork and the Swedish suspension sultan’s TTX36 GP rear shock, both of course fully adjustable
Hard though it is to ignore the extra power and greater torque of this fabulous engine, it’s the ultra-refined handling of the BMW HP4 RACE that really impresses. Thank its light weight and especially those carbon wheels. Try as I might to prepare myself after spending my first session at Estoril riding a 2017-model S1000RR streetbike fitted with the same Pirelli slicks as the HP4, after switching bikes I found myself doing the same thing I’d done a month earlier when riding the comparable Ducati 1299 Superleggera at Mugello, also equipped with carbon wheels. I’d keep oversteering into the apex of a turn, especially at Estoril’s slow uphill chicane, so I initially had to pick the BMW up again, and correct my line.
I’ve been riding on carbon wheels ever since 1994, when I began helping Dymag develop such a design by racing on them, so I know how greatly they influence turn-in and steering, and I always recognise you have to be ready to compensate for them. You must focus on using a lighter touch in steering the bike, which I’d honestly thought I was doing. But then I realised that I hadn’t taken into account the even lighter weight of the new BMW’s carbon fibre frame compared to its S1000RR streetbike sister’s aluminium chassis I’d been riding earlier, as well as all the copious other black magic bits on this uber-lightweight motorcycle.
This made the BMW HP4 RACE’s steering ultra-light, especially when flicking from side to side in the complex of corners from Turn 1 onwards at Estoril, yet without sacrificing stability on the faster bends. Truly the best of both worlds – the lighter carbon fibre chassis structure and all the other CF parts definitely make the new BMW more nimble and responsive as well as less tiring in changing direction, especially at lower speeds, when it turns super-easily and hugs your chosen line tightly. This bike is faster steering and more agile than any other four-cylinder Superbike I’ve yet ridden. Too bad that BMW can’t homologate it for WSBK!
Carbon-framed motorcycles are like buses: you wait three decades for another one – ever since the first such bike, the Armstrong CF250 road racer that debuted at the 1983 British GP at Silverstone – and then three come along one after another, each quite different one than another. First was last year’s surprise packet, the Dutch-built VanderHeide with its carbon monocoque chassis incorporating the 24-litre fuel tank. Then came the 500-off Ducati 1299 Superleggera with its vestigial carbon semi-monocoque that’s really just a CF airbox used as a structural entity. Now, perhaps most relevant of all, comes this BMW with a conventional twin-spar frame made in carbon rather than metal, but using a manufacturing technique that makes it cost-effective to commercialise.
BMW Motorrad has chosen to start at the top, by using carbon fibre extensively to produce an ultra-lightweight, high-performance, customer-available motorcycle with the performance of a factory Superbike racer. But it’s inevitable that the economies of scale will see a trickle-down effect that’ll result in BMW’s CF technology being applied to other models in its range. So what’s next – maybe a G310R-based HP1 RACE??!
Photos: Daniel Kraus and Markus Jahn
