Lead Out

How can you im­prove on a bike de­signed by a su­per­com­puter? Add disc brakes, of course

Cyclist - - Contents - Words JAMES SPEN­DER Pho­tog­ra­phy TAPESTRY

How does BMC im­prove a bike de­signed by a su­per­com­puter? Think disc brakes… Gear from Zipp, Giro, dhb and more Tour de France or­gan­iser Chris­tian Prud­homme on why he loves Bri­tain Yanto Barker on the etiquette of wear­ing the piece of kit that will de­fine you: sun­glasses The best home gym kit for cy­clists Frame build­ing veteran Carl Strong re­veals the ethos be­hind his 3,500 bikes In praise of… pro team spon­sors The Rocket7 shoes that take in­spi­ra­tion from speed skat­ing to tur­bocharge your feet Frank Strack ranks the tough­est pro rid­ers

Cadel Evans knows the BMC Team­ma­chine bet­ter than most. ‘I reckon I’ve done 150,000km on ev­ery it­er­a­tion of the SLR,’ he says. ‘I would say this, of course, but this new bike is ex­cep­tional. It has the same ge­om­e­try as the orig­i­nal, that same nim­ble­ness that al­lows you to hit a 46cm gap with 44cm bars, but it’s got discs. And as I’ve al­ways said, if you can’t go fast, at least look good.’

As a BMC am­bas­sador, the 2011 Tour de France cham­pion has a vested in­ter­est in talk­ing up BMC’S re­designed flag­ship, but he might just have a point.

The pre­vi­ous gen­er­a­tion of the Team­ma­chine SLR gar­nered praise across the board for its sharp han­dling and im­pres­sive stiff­ness, yet many pedi­gree race machines have suf­fered as a re­sult of the ad­di­tion of disc brakes. Changes in ge­om­e­try to ac­com­mo­date wider hub spac­ing and smooth chain­lines, not to men­tion heav­ier com­po­nents, left many early disc brake fans dis­ap­pointed – our­selves in­cluded. With the SLR Disc, though, BMC ap­pears to have blended in disc brakes al­most seam­lessly.

First up, ge­om­e­try is un­changed save for the chain­stays, which have in­creased from the 402mm of the rim brake model to 410mm. That’s less than the 415mm or 420mm stays of many other disc bikes, and cru­cially, says BMC engi­neer Tobias Habeg­ger, it’s not enough to make the han­dling dis­cernibly dif­fer­ent to the pre­vi­ous gen­er­a­tion: ‘We knew that gen­er­a­tion was good, so we wanted to keep that bike’s char­ac­ter­is­tics. It was hard to im­prove on that as a rim-braked bike, but the discs threw up a whole lot of other chal­lenges.’

Those chal­lenges have been met thanks to a pro­to­typ­ing process BMC calls ACE – Ac­cel­er­ated Com­pos­ites Evo­lu­tion – which it used to great fan­fare for the pre­vi­ous Team­ma­chine. Us­ing su­per­com­put­ers, BMC ran an al­go­rithm it had de­signed that gen­er­ated and tested dif­fer­ent pro­to­types of the bike vir­tu­ally. Engi­neers pro­vided the pa­ram­e­ters – for ex­am­ple, tubes must be no big­ger than the UCI’S 3:1 ra­tio – then they hit ‘go’. One year and 34,000 pro­to­types later, the com­puter gen­er­ated the ‘per­fect’ bike.

‘We changed the pa­ram­e­ters for the in­clu­sion of disc brakes,’ says Habeg­ger. ‘That led the com­puter to run through a fur­ther 18,000 new it­er­a­tions be­fore we came to the new Team­ma­chine. ACE also now combines shape and lam­i­nate, mean­ing it si­mul­ta­ne­ously works on the shape and the best car­bon fi­bre lay-up

process, in­stead of first defin­ing the shape, then defin­ing the best lay-up for that shape.’

The re­sult is a disc bike whose frame weighs a claimed 815g, which built up as pic­tured weighs 6.8kg (painted, size 56cm), which BMC says han­dles like a nim­ble race bike but with the added ben­e­fits of disc brakes.

Same but dif­fer­ent

The trade­mark BMC gus­set un­der the top tube has now been filled in, partly to save weight and partly to ac­com­mo­date the new clamp­ing mech­a­nism, which is neatly hid­den in the un­der­side of the top tube. The seat­stays lose the brake bridge, again sav­ing weight and al­legedly aid­ing com­pli­ance, while the fork gets an over­sized left leg.

‘What most man­u­fac­tur­ers do is add ex­tra ma­te­rial to re­in­force the fork against disc brake loads,’ says Habeg­ger. ‘This typ­i­cally makes it 4050g heav­ier. What ACE told us to do was to build the fork asym­met­ri­cally, so the left leg has a much wider cross-sec­tion but very sim­i­lar wall thick­nesses to the right leg, so over­all the fork is only 18g heav­ier than be­fore.

‘We haven’t changed much with the tube shapes, as they were op­ti­mised al­ready within the UCI rule­book,’ he adds, but says ad­vances in com­pos­ites have helped in­crease stiff­ness by 10% at the bot­tom bracket, with­out ad­ding sig­nif­i­cant weight.

As an aside, Habeg­ger also says the paint on a frame ‘ac­counts for around 10% of the frame’s weight’, but that a ‘naked’ ver­sion of the frame is avail­able, al­beit specced with Shi­mano Ul­te­gra. The up­shot is that, some­what coun­ter­in­tu­itively, the lower-spec Team­ma­chine has a lighter frame.

Else­where, the junc­tion box and charge port for the new Shi­mano Dura-ace Di2 has been in­te­grated into the down tube and the frame uses Shi­mano’s new direct-mount cal­liper mount­ing. BMC has also specced its own in­te­grated stem with a re­cessed un­der­side to hide the ca­bles, and a fork steerer with flat­tened sides to let ca­bles run in­side the head tube with­out in­hibit­ing the ro­ta­tion of the bars.

Whether the new Team­ma­chine Disc re­ally does ride as well as its fore­bears re­mains to be seen when we do a full test in an up­com­ing is­sue of Cy­clist.

BMC Team­ma­chine SLR01 Team Disc, €11,499 (pic­tured, ap­prox £9,989). En­try level Team­ma­chine SLR02 Disc from €3,699 (ap­prox £3,223)

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