PEZ-Clusive Test: BMC SLC01
Another world’s first look from the Pez-Crew – this time the completely re-designed 2006 BMC SLC01 ‘Pro Machine’ – the 100% carbon fibre frame made from Easton’s “CNT“ Carbon Nanotube Technology is stronger, stiffer, and lighter than before… but how’s the ride? Here’s what PEZ Sez…
We managed to scoop this bike just after Interbike last year, and were lucky enough to get one of about 10 that existed in North America… even before most dealers, and well before stock arrived.
Gregory Rast’s Team Phonak BMC SLC01 in Milano at the start of la Primavera last Saturday. – Click the thumbnail at top to see the jumbo version.
To get things rolling, we asked Floyd Landis how the new SLC01 Pro Machine compares to the older Team Machine: “The weight is the biggest factor. Having the lightest bike around should get it done. The Pro Machine is lighter, and more comfortable, but you still don’t give anything up. It is really stiff at the bottom bracket. The bike is perfect for what I need it to do.”
Okay, a good start, and if anyone can flex out a bottom bracket, he’s likely a ProTour rider, but why take his word for it – doesn’t he get paid to say that stuff? Let’s take a look for ourselves…
I admit to being enamoured of BMC bikes, my personal ride for 2005 was their SLT01 Team Machine – regaled in full Phonak colors [and stolen from my garage!… Tech Ed]. Sure it made for a decidedly “EuroTrash” rainbow of colors when mixed with the mighty PEZ-Kit, but for anyone not afraid to be different – the BMC’s unique exo-skeleton frame design, coated in the yellow, green and white Phonak colors was the ticket. The bike was also a pleasure to ride – stiffer than Stifler’s Mother at the bottom and through the drive train, but with improved long-ride comfort achieved through carbon layup, geometry, Easton’s EC90 carbon fork, Zipp’s 303 carbon clinchers, and Modolo’s Curvissima KX carbon bars – for me it’s a great ride. But I was keen to see just how much they’d changed the 2006 model…
A boy and his bike (the SLT01) sharing good times on the Stelvio.
Stuck On One Detail
Leave it to the Swiss to hang onto fixing details like a dog with an old bone… and after only 2 years of SLT01 production, they’ve redesigned the bike from top to bottom.
The detail in this case – was weight. BMC weighed the SLT (55cm) frame in at 1260 grams (2.74 lbs). And while the Phonak boys were equipped to bring the bike in at UCI minimums by using various ultra-light parts, the rest of the bike- buying public was apparently more vocal about wanting a frame that could be part of an even lighter bike. “Make it lighter!” was the cry heard at BMC hq in Grenchen Switzerland.
BMC says the new SLC01 frame weighs in at 960 grams (2.11 lbs), and that, my non-conversion savvy friends, is almost 2/3 of a pound lighter (that’s 10 whole fat ounces!) than the SLT01.
Where Are The Hacksaw Marks?
Ten (10) ounces is weight you can feel when you lift the bike and that’s serious stuff. So how’d they do it? Simple, sort of – they redesigned the frame, eliminating the aluminum lugs, and replaced the whole thing with a 100% carbon fibre frame made by Easton with their CNT Composite technology. Easton believe their CNT is the lightest, strongest frame material available today.
One thing the guys at BMC do know, is that if they don’t know something themselves, they find someone who does. They’d already been working with carbon-meisters Easton with OEM spec of forks, bars, stems and seatposts, and knew firsthand the expertise the American partner could bring to the table. Easton has long been setting high standards for aluminum tubing used in all kinds of sports, from baseball and softball to hockey and archery and have been in the carbon component game for years, so it was natural to apply this mindset to creating carbon-fibre tube sets too.
Easton makes their carbon-fibre products at their own factory in Taiwan, (where much of the world’s best carbon fibre is made), and we’ve been impressed with their forks and handlebars, so why not a bike frame…?
What’s Up With CNT?
Although they didn’t invent ‘carbon nanotube technology’, Easton’s own Carbon Nanotube Technology (CNT) was introduced in late 2004 and fit the bill as material of choice. Going to a full carbon-fibre frame (losing the aluminum lugs from before) was the route – not just because full carbon frames are ‘de regeure’ these days, but also because Easton’s CNT made perfect sense to address the weight, ride quality, and strength levels they wanted.
The SLC01 frame is full CNT carbon – even the dropouts and the head set bearing surface, in fact the only metal part is the BB thread alloy insert.
Rolf Singenburger of BMC told me there is: “no machining on carbon parts, we don’t cut any of the fibers, everything is molded in, so precise that we don’t need to machine the seatpost inner diameter, no machining on the headset bearing surface, all cable routing is molded in, even cable stoppers on top- down tubes and on chainstay as well are all co-molded!”
Okay so this CNT stuff sounds strong, so I asked Easton for the scoop. We had a few long conversations marinated in technical jargon, but the boiled-down deal on their ‘CNT’ Carbon Nanotube Technology – is that tiny tiny tiny (you can’t even see ‘em) tubes of carbon fiber (ie: ‘nano-tubes’) are mixed into the resin which bonds the carbon sheets together, and work to add strength to the resin much like using wire-mesh in concrete does. The weight of the finished carbon fibre product (in this case the frame) is reduced because the CNTs take up space in the resin where resin would normally be, but weigh less than the resin they displace. Exactly how much weight the CNT’s save vs other carbon was unclear, but going back to the full frame weight comparison (remember 300grams lighter) it’s evident the CNT accounts for something. Got it?
The next two pics show cool detail of their carbon nanotubes (CNTs) revealed in a fracture test:
Image courtesy Easton
Image courtesy Easton
Building A Better BMC
Rolf also explained that the design criteria was straight forward – make a ProTour-quality race bike that preserved the drivetrain response with a very stiff bottom-end / drivetrain, while maintaining enough compliance and comfort through the rest of the frame to suit 7-8 hour race days – but this time make it lighter than the SLT01.
In addition to being different on the inside, the 2006 frame also looks quite different on the outside. Much more streamlined, it’s not a monocoque frame [but then there are very few real “monocoque” frames despite the large number of folks that claim it… Tech Ed], but instead is a series of carbon tubes joined by carbon lug joints – though not in the traditional lug/tube–sense.
Last year’s SLT01 featured the unique exo-skeleton design of ‘suspending’ the seat tube inside the lugs vs using it as a bracing part of the structure, and used solid ‘vibration-blocking’ aluminum lugs that dampened vibrations from traveling to other parts of the frame. The result was a super stiff frame, but with a higher degree of comfort than you’d expect, thanks to the layup of the carbon tubes.
Here’s a quote from our first BMC Pez-review and is also accurate again for this bike: “The interesting part is that the BMC doesn’t mute the larger bumps like some other Carbon does (but then that’s not what road bikes are for anyway…). That must be the trade off for all of the design concentration on stiffness. Overall the ride is quite good, very acceptable given the bike’s performance.
The ‘skeleton’ of the SLC01 is integrated into the frame, and some very visible design differences make this frame work.
A bottom bracket alone doesn’t prevent flex, but when mated with the deep section chain stays, seat tube and down tube, the BMC does a darn good job.
STARTING AT THE BOTTOM
One of the prime design criteria (maybe the primo!) for the SLT01 was a stiff bottom end – BMC wanted it for the Phonak team and the result was a bb platform as big and substantial as anything we’d seen. The huge aluminum “box” that anchored the drive train was also reinforced with gussets to anchor the seat tube – pretty much nothing short of King Kong could flex that bad boy.
Big Beef BB
For 2006, the SLC01 maintains one the beefiest bottom ends around – it’s a one piece unit molded from Easton’s CNT, that (when separated from the bike) looks sort of like a huge spline with the base of the down tube, seattube, and chain stays sticking out several inches. Both the downtube and the seattube widen to full BB width to provide big lateral stiffness, and the big box section behind the actual bb extends well back towards the rear wheel – further than anything I’ve seen.
There’s the Beef! When your number 1 criteria is a stiff bb, you make sure you put material where it’s needed. The slick design for the internal cable routing was a nice touch.
BB Envy: It’s not just the girth… it’s the length that makes it stiff. Photographic evidence that the BMC BB is about as wide as you can get, and note how long it extends to the back.
Moving our attention up front to the steering end of this rig, the head/ top/ down tube junction stands out with some shapes that do more than look cool. The I-beam style design of the top tube starts full width of the headtube, before tapering down slightly towards the seatube (see pic below).
The down tube is massive and makes for a great graphics platform. Easton’s CNT process allows for very nice detailing like the in-moulded cable guides. Going the opposite way of the Top tube, the down tube gets wider as it approaches the bb.
The joining areas of tubes and lugs are plainly visible on the skin.
Big Lugs Well, not in the traditional sense, but BMC’s version the head tube, bottom bracket, and seat tube clusters are molded CNT carbon fibre that is bonded to the top-, seat-, and down-tubes – but the junctions are further along the main tubes. In the pics above and below, you can see the junction of the headtube/ downtube about 2 inches below the headtube, just behind the cable guides. The design allows for strength in critical areas at the junctions, and thinner, lighter tubes in areas of less stress to reduce weight.
MOVE RIGHT TO THE BACK
• The Rear End is slightly more compact than before, and uses their wishbone seat stay design to keep things very stiff. The ride however, was more comfortable than expected.
Most of us notice that ride quality is hugely influenced by wheels and tire pressures (I run 110-120psi), and DT Swiss 1450 wheels were also a nice riding wheel – I’d say not as comfy as Zipp 303’s (the most comfortable wheel I’ve ridden) but around 100 grams lighter for the set. I would have liked to keep these wheels around longer.
• The seat/ top-tube/ seatstay junction looks very different from last year, but serves many of the same functions. The design is much more streamlined, less industrial and way more sexy. Back though, is the integrated two-bolt seatclamp which reduces stress on the seatlug and on the carbon seatpost by spreading the clamping force over a wider area than a single bolt clamp. The ‘bridge’ from the seatclamp down to the wishbone helps transfer the saddle load smoothly to reduce stress on the top of the seatpost, where cracks often occur.
The cut out area to the front to the seat tube makes the frame more rigid by reducing the size of the front triangle and adding direct connection to the rear wishbone through a lower position along the seattube, that also reduces the size of the rear triangle for better efficiency on power transfer.
The guys at BMC told us “This part shows the state of the art production process, very difficult to produce, [that] needs an important development in tooling design.”
• Carbon dropouts – Easton tells me they’re as strong as aluminum but lighter, and bond better to the carbon frame tubes… that makes good sense. They aren’t machined either – they’re molded, which eliminates the need to further stress the carbon by grinding away material. Also note the big curve of the chainstays – looks cool, provides plenty of clearance for your feet, and are designed to increase the lateral stiffness of the rear end vs. straighter stays.
Check out the shape detail on the sides of the stays – again designed with purpose in mind to add strength and response to the frame.
How fat are those stays? They’re the fattest I’ve seen, and I expected a harsh stiff ride to match. But nooooo – this bike I could pedal for hours. The tall height of the stays adds vertical stiffness and twist resistance.
ON THE ROAD
To say I eagerly anticipated the “new ride” would be an understatement… and this bike delivered it with top priority. My over-riding impression was amazement at just how comfortable this bike is. It’s as stiff as I needed, especially climbing and accelerating hard, but forgiving enough that I could pedal it happily for hours. The frame geometry is the same as the SLT01 (72° headtube angle, 73.5° seatube), pretty standard road geometry, but not as steep as some guys prefer.
Jagwire cables were a nice touch worthy of a ProTour-pedigree machine.
It’s a frame well suited to strong pedallers, stable and true over varied terrain and surfaces, and the turns are carved like those on long skis – you know where you’re going to exit right from the start (barring any operator-induced directional redirection).
The thing that most surprised me was the ride quality. Don’t get me wrong – it’s Not the smoothest ride out there, (it is a race bike after all), but based on the sheer size of those tubes and chain stays I expected something much harsher than this bike delivered to my 138 lb. person. It was definitely more comfortable than the SLT01.
Is it stiff enough for you…? It’s the same frame that Team Phonak rides, and if it’s stiff enough for Floyd, my guess is yes – it’ll do you just fine.
I weighed the 51cm test bike at 16.8 pounds with Shimano pedals and 2 cages.
Price: $3650 US – frame/ fork/ headset
Where To Get ‘Em
• For a US dealer near you check BMC-Cycling.com
• For an international dealer near you check BMC-Racing.com
• In Canada – special thanks to Ed at MightyRiders.ca for the fine build up!
Note: if you have other experiences with gear, or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews, or a slap in the head if you feel the need!
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