‘THIS IS JUST THE START’
New HP4 Race is the beginning for the mass-produced carbon-fibre motorcycles
BMW’S Christian Gonschor is looking proudly at the BMW HP4 Race – the culmination of the project that he’s led for the last three years – and perhaps an indicator to the direction of future BMW road bikes. “To be involved in a project like this is a dream,” he says, “but it must be our target for full mass production. The second step must be carbon-fibre in road bikes.”
We’re in building IH, deep within BMW’S R&D department in Munich. This is the building that BMW’S four and six-cylinder production bikes are masterminded and plans are hatched. The very bench the HP4 Race is sitting on sometimes houses a machine from a rival manufacturer, laid bare and showing its secrets – like every other bike firm BMW buy their rival’s products and strip them to work out why and how.
But today it’s one of their own products sitting on the bench – a machine that could signal the biggest change in frame technology since Suzuki introduced the first aluminium frame in 1983. Of course, the HP4 Race isn’t the first motorcycle to have a carbonframe, and Ducati’s new Superleggerra also has a carbon monococque but the BMW is the first one produced with truly industrial methods. With a production run of 750 units, BMW have constructed the HP4’S frame using the same technology that’s used in the complete chassis on their i3 and i8 electric/hybrid cars.
But unlike those cars, where the use of carbon was to reduce weight and therefore improve economy, the HP4 Race’s use of carbon fibre is for performance. The HP4 is dripping in black gold – the frame, subframe, wheels, and fairing are all made from the wonder weave.
If you’ve read the road test on the preceding pages you’ll know that the result is a machine with cutting-edge performance. The power output is impressive, but it is the claimed fullyfuelled weight of 171kg that takes your breath away – that’s 37kg lighter than a production S1000RR. In fact, it’s even lighter than a BMW WSB bike.
Manufactured as a single piece (a normal S1000RR frame consists of cast-alloy headstock, spars and crossmember sections that are welded together) carbon saves 4kg, reducing the weight of the frame from 11.8 to 7.8kg.
But there is more to carbon fibre than just lightness. “The great thing is that you can do what you want when it comes to stiffness, flexibility and weight. You can play with vertical stiffness for braking while allowing the horizontal flexibility you need for cornering, feedback and edge grip. You can place the stiffness exactly where you want by altering the layering and direction of the carbon cloth’s weave.”
‘It must be our target for full mass production of carbonfibre road bikes’
In 2009 BMW went into a joint venture with specialists SGL to find cost-effective ways of producing carbon parts for their cars. Normally, carbon-fibre cloth pieces are laid up in a mould and either baked in an autoclave and/or vacumn-bagged to help remove air bubbles in the resin that gives the carbon cloth its stiffness.
But SGL use a process called Resin Transfer Moulding, a mechanised technique that allows fast construction. “We assemble all the cloth elements of the frame and all the ally inserts, put them in the mould together with a core. We clamp the mould and insert the resin under high pressure, meaning the whole structure is smooth and constant. It’s ready in two hours. All that needs to happen then is machining of the ally and the lacquering.”
But it’s not cheap – the tooling cost is huge. As well as the expensive machinery, there’s the machining of the male and female heated moulds, which needs huge accuracy. It suggests that BMW are planning a road bike – you need big numbers to break even.
Keen to make carbon work
The frame’s testing procedure has been exhaustive. Impact tests, crash testing, the testing of the frame with cracks and damage – it’s even been tested for its strength and safety in sub-zero conditions. This are all things that a track bike would never encounter.
“We wanted to prove the performance, weight and industrialisation of carbon fibre. The concept shows that carbon fibre is the next step to the future.
“We’ve already shown it as an optical thing, but it can be structural too. It’s the perfect material as there are no limits. We know carbon can work.”
‘It’s the perfect material for an engineer, you can do exactly what you want’
BMW HP4 RACE Christian Gonschor Project leader
Gonschor explains carbon to MCN man Wildee
view regularly 750 super-rich, super-skilled, super-lucky trackday riders will see this
The frame has machined ally loadbearing inserts
RTM gives each frame a unique fingerprint