BMC revisits aluminium and carbon fibre in its latest frameset

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Tech feature: BMC SLX01 Racemaster launch, June 16, 2008

To coincide with its national tour, Swiss bike company BMC is launching a new frame into its road range: the SLX01 Racemaster. Cyclingnews sends Ben Atkins to Switzerland for a sneak preview and test ride.

Whether or not you like their look, BMC's road frames are certainly unmistakable for any other brand and its latest SLX01 Racemaster continues the trend. The new frameset, which will slot in below the existing SLT01 Team Machine in terms of cost, integrates a number of now-familiar design elements such as the 'T'-shaped top tube that splits before joining the seat tube, the compact rear triangle, a down tube and seat tube that flare to the full bottom bracket shell width, and internal cable routing.

Like the Team Machine, the new Racemaster is an aluminum and carbon fibre hybrid but how and where those materials are used are completely different between the two. Whereas the former uses carbon fibre tubes throughout with unique aluminium lugs, the Racemaster recalls LeMond Bicycles' 'spine' concept with an Easton CNT-enhanced carbon fibre top half joined to a bottom half made almost entirely of hydroformed and tripled-butted 7005 aluminium.

The so-called 'Aluminium Trident' includes the down tube from just aft of the head tube, the entire aero-shaped seat tube and the tall multisided chain stays. Up top, the 'Carbon Arc' includes the top tube, head tube and remaining portion of the down tube - all of which form one continuous section - and the separately formed wishbone-style seat stay assembly. Nearly everything (including the forged aluminium dropouts) is bonded together with conventional welds used only at the bottom bracket shell.

According to BMC, this configuration delivers a far more rigid bottom bracket than its other models but still excellent comfort and road feel. However, the cost for this is paid at the scale as claimed weight for the frame alone is 1400g - still respectable but roughly 40 percent heavier than the top-end SLC01. The included BMC-branded fork pushes that disparity even further as its carbon legs and crown and mated to an aluminium steerer.

BMC feels the weight is a price worth paying for the 'incredible' bottom bracket stiffness, though, and the extra mass will thankfully be reflected in the price tag: an SLX01 Racemaster frame, fork, headset and seatpost will fetch a reasonable US$2595.A seatpost? What seatpost?

One could easily be fooled into thinking that the Racemaster includes an integrated seatpost with its impossibly clean lines and matching aero profile but a closer inspection reveals BMC's new 'Streampost 73.5' design. The concept, borrowed from the company's TT01 Time Machine, uses an internal aluminium wedge at the base of the post linked to a simple 'angle lock' toggle-like switch up top via a tiny carbon fibre tube. The patent pending design is essentially a rehash of old quill stems but brought into the modern age. According to BMC, the angle lock system can't be overtightened as long as the initial one-time setup procedure is done correctly and the entire assembly is surprisingly lightweight at just 220g.

For now, BMC will offer the Streampost 73.5 in but a single offset, meaning riders typically requiring a more forward position unfortunately might be out of luck.

Head for the hills

We set off on a new Racemaster in the picturesque surroundings near the company's headquarters at Grenchen, in the north of Switzerland. Sadly the weather was not on our side as bright sunny skies quickly clouded over and rain - which quickly turned to hail - moved in, but we were still able to take in some nice roads and get a positive first impression.

BMC's claims about the frame's stiffness, particularly around the bottom bracket area, proved to be well founded with notably solid-feeling and efficient power transfer afforded by the big aluminium tubes.
Our particular Shimano Ultegra equipped tester perhaps lacked that flighty feeling of the true featherweights we've grown accustomed to when heading uphill but the frame's superb stiffness helped to make up for this as climbing was predictable and straightforward nonetheless.

Not surprisingly, the newfound sureness of the steering and competent frame geometry also made descending a sure and safe experience, so much that we comfortably pushed the limits on some rather technical turns on roads that were only just beginning to dry after the heavy rain.

Who's it for?

Although slightly less expensive than the SLT01 Team Machine, the SLX01 Racemaster is both lighter and more rigid, meaning that riders looking solely at the performance numbers (or those that simply prioritize bottom bracket rigidity above all else) are likely to choose the new model over BMC's best seller. In fact, while the majority of BMC's professional teams ride Pro Machines, BMC Racing's Martin Kohler is said to be riding the Racemaster at the Tour de Suisse.

BMC expects the Racemaster to be built mostly with Shimano Ultegra or Campagnolo Centaur-level componentry in full-blown race spec - with Campagnolo Record and Easton's EC90 carbon wheelset - a complete 54cm bike without pedals still comes in at a highly respectable 7kg. The frame will be available in six sizes: 49, 52, 54, 56, 58 and 61cm, all of which should now be available at BMC dealers.