Ingezonden

BMC launched the new GranFondo GF01 ‘endurance’ model in Kortrijk, Belgium just ahead of the start of Paris-Roubaix (James Huang/Future Publishing)

BMC have debuted a new carbon fiber GranFondo GF01
‘endurance’ model that the BMC team will race this Sunday at Paris-Roubaix.

While team riders Thor Hushovd, Taylor Phinney, and George
Hincapie will use the additional comfort and handling stability over the
cobbles, the new bike will likely prove well suited for just about any rider
looking to cover lots of distance quickly, but without beating themselves up.

Key features on the GF01 include use of BMC’s Tuned
Compliance Concept, as well as a new concept called ‘angle compliance’. As on
the TeamMachine SLR01, the new GF01 features specially shaped tube sections to
promote directional flex over bumps. This is most notable in the seat stays,
which are dramatically flattened from end to end.

BMC frame designers also acknowledge that from a purely
geometrical point of view, merely flattening particular tube sections isn’t as
effective as it could be — after all, a triangle with one straight side that’s
thinner than the others still doesn’t want to compress. Therefore, BMC have
built in additional kinks at the top of the seat stays, just ahead of the rear
dropouts, and just above the fork tips to act as pseudo-pivots that flex under
load.

Moreover, the rear dropouts are intentionally offset
rearward — creating a short moment arm — that further promotes flex when
hitting bumps.

The giant chain stays transmit more road buzz but that’s apparently what the BMC team wanted — a stiffer feel in normal conditions but a softer ride when the going gets really, really tough

TCC and ‘angle compliance’ are built into the 27.2mm-diameter
carbon seat post, too, which will be available in three setbacks — the standard
18mm plus 3mm and 30mm options – each with its own specific lay-up schedule and
flex pattern. Taken in total, BMC claims a 40-percent improvement in
comfort for the GF01 over the SLR01
— a bike already we found to already be unusually comfortable for a race bike
.

Engineering types may view the built-in flex points as areas
of focused stress, but when asked by BikeRadar BMC frame engineer, Jonas
Müller, insisted it’s not a concern, saying GF01 frames have exceeded all
industry standards and in-house tests, and moreover, there is no rider weight
limit. BMC also offer a five-year warranty on the frame and fork with an
optional crash replacement program for top-end models as well.

More comfortable,
stiffer, but with tweaked geometry

BMC of course, claim that there is no effect on overall
frame torsional rigidity or drivetrain efficiency, either. In fact, BMC say
internal testing shows the GF01 to actually be about 20-percent stiffer than
the SLR01 at the bottom bracket and more than 30-stiffer in full torsion thanks
in part to the BB86 press-fit bottom bracket, the larger 1.5in lower
diameter on the tapered steerer tube (the SLR01 is 1.125in), and the
correspondingly bigger down tube and seat tube profiles and more widely spaced
chain stays.

The BB86 press-fit bottom bracket leaves lots of room for bigger down tubes and seat tubes, not to mention chain stay spacing that’s also wider to reinforce the back end. Shimano Di2 batteries mount underneath the non-drive stay

Claimed frame weight for the GF01 is still less than 1,000g
for a 54cm size — a penalty of less than 100g compared to the SLR01.

As is typical for this genre of bike, BMC has slightly
tweaked the frame geometry for additional stability and slightly more relaxed
handling. Changes relative to the SLR01 include a slightly slacker head tube
angle (by about half a degree), extended head tubes by a modest 7-12mm, longer
front and rear centers, and 2mm of additional bottom bracket drop though that’s
essentially offset by the bigger tires (more on that later).

Even with room for 28mm-wide tires, the brake pads don’t need to be slammed all the way down in the adjustment slots

Keeping in mind the cumulative effect of all the changes —
the fork axle-to-crown length is longer, too — the effect on stack and reach
are a little more significant with 8-16mm decreases in reach, and 14-19mm
boosts in stack depending on size. As a result, the GF01 will offer slightly
more relaxed handling but also a modestly shorter and more upright fit than
BMC’s more race-oriented options.

T’s crossed, I’s
dotted: DTi, chain watcher, and tire clearance

BMC continues the so-called ‘gran turismo’ theme with the
ancillary features and even the standard component spec. The new DTi (Dual
Transmission Integration) routing setup is designed for easily maintained
external cable routing but the stops are removable (cosmetic covers will be
included at production) for use with internally run Shimano Di2 or Campagnolo
EPS wires.  At least in the case of Di2, the battery is fixed to a
dedicated mount beneath the chain stay.

Wires for electronic drivetrains enter the frame in the top tube, just ahead of the brake housing stop

The bottom bracket sports a rigidly mounted integrated chain
catcher with interchangeable bits that will work with standard or compact
double cranksets as well as triple setups.

The novel integrated chain catcher is anchored in the bottom bracket shell and features interchangeable bits for use with standard, compact, and triple cranks

One of the most impressive features on the GF01 is clearance
for up to 28mm-wide tires, which will come as standard equipment on complete
bikes, while still using standard-reach brake calipers. BMC raised the brake
mounting holes relative to the rim as is typical for this sort of design goal
but they’re also cleverly angled, too.

The rest of the spec is similarly well thought out, such as
tubeless-compatible Easton EA90 RT rims with 22mm-wide profiles, wider and more
generously padded fi’zi:k Aliante saddles, and compact-bend Easton handlebars.

Total claimed weight for a complete GranFondo GF01 with
Shimano Ultegra Di2 is just 7.38kg without pedals.

BMC isn’t ready to release retail pricing on the GranFondo
GF01 just yet – the company wants to wait until it’s presented to dealers in a
couple of weeks — but BMC road product manager Andrew James tells BikeRadar that it will be comparable to
the TeamMachine SLR01.

Complete bikes in various configurations as well as a
frameset option will be available following the autumn trade show season.

Check back to BikeRadar for an upcoming first ride review of the new GranFondo GF01.

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