‘THIS IS JUST THE START’

New HP4 Race is the begin­ning for the mass-produced car­bon-fi­bre mo­tor­cy­cles

Motorcycle News (UK) - - This Week - By Matt Wildee SE­NIOR ED­I­TOR

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’

Mass pro­duc­tion

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

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