2008 Felt B2 Pro.
By Tom Demerly.
Sometimes it’s good to be second.
This is the second year for the molded carbon
fiber Felt B2 frameset. The 2008 Felt B2 frameset is the result
of Felt’s experience over the previous decade with their
DA and B2 triathlon bikes and with molded carbon fiber from
their “F” series road bikes. This is the frame
used for the new 2008 Felt B2 Pro. In Felt’s case, waiting
to introduce the new carbon B2 until last year has resulted
in improvements and a proven track record for the new 2008
Felt B2 Pro.
The Felt B2 Pro's
molded carbon fiber construction produces stronger,
lighter, stiffer and more comfortable frames than any
other construction technique.
By being a more recent
arrival to the molded carbon fiber tri bike market Felt
enjoys the benefits of benchmarking the best and avoiding
the worst of what is already available. They’ve
done an impressive job of keeping the good from previous
designs (theirs and other companies), building some
new and valid design innovations and avoiding some serious
pitfalls with all-carbon fiber molded designs.
Felt caught the second wave of molded
carbon fiber tri bikes after sitting out the first round
of offerings. It was a good strategy. Three or four
years ago when Cervelo, Kuota and others were rolling
out their molded, aerodynamic carbon super-bikes Felt
was still offering a tired looking (albeit solid) flagship
triathlon bike that was trimmed in carbon fiber but
was still aluminum. Consumers yawned. If it wasn’t
carbon they weren’t interested.
Consumers may not understand why they
want carbon fiber, but they do. The facts behind molded
carbon bikes are compelling. As consumers learn the
facts the more desirable the material and construction
technique will become. Molded carbon bikes are lighter,
stronger, more aerodynamic, soak up bumps and road shock
better and have stiffer bottom brackets and head tubes
for better climbing and handling than previous frame
materials such as aluminum, titanium and cro-moly. In
a well conceived design it is difficult to find a single
drawback to molded carbon fiber except cost. Engineering
tests on the durability of molded carbon fiber frames
demonstrate they are more durable and lighter than titanium
in both fatigue testing and impact testing. Molded carbon
fiber has become the reference material for ride quality
and frame stiffness, two divergent agendas. Molded carbon
fiber frames have also become the most durable way to
make a bicycle.
The 2008 B2 Pro is the culmination
of decades of Felt's experience and a significant improvement
on the 2007 model year B2's.
Tim DeBoom at the 2007 Ford Ironman Hawaii on a carbon
fiber Felt equipped with Bayonet front end and hidden
rear brake. These design innovations are the result
of extensive wind tunnel design and testing along with
advanced flow analysis as seen in the graphic (right).
In the competitive arena molded carbon fiber
bikes dominate the winner’s circle like no other material
in history has, winning from Kona to the Tour de France and
at every local triathlon in between. Molded carbon fiber frames
are now the standard against which others are compared, and
the others don’t compare too well. It was inevitable
that Felt would develop a molded carbon fiber triathlon bike.
The trick was to introduce something better than what was
already in the marketplace.
Felt also needed improvements in the most important
area of tri bike design and performance: fit and position.
Felt’s previous triathlon geometry was decidedly old
school with 76 degree seat angles, longish top tubes and lowish
(too low) head tubes. It was difficult making those geometries
work for some riders. Felt needed to step into the current
age of triathlon geometries born out of a better understanding
of how triathlon bikes should fit to improve comfort, stability
and performance on the bike and in the run. The bikes needed
to be shorter in the top tube, higher in the head tube and
steeper in the seat tube to give riders a better fit and better
run off the bike. Felt needed to improve their earlier geometries
for better skeletal support of the torso on the handlebars
and for improved comfort and improved front end stability
for easier handling.
The “To Do” list in the
design of the new B2 was a long one. In 2008 the B2
Pro does a strong job of completing that list.
Felt’s new 2008 B2 Pro hits a sweet
spot in the line up of carbon tri bikes across every
brand with high value and the most eclectic sampling
of bike industry components and upgrades along with
Felt’s “Bayonet” front end. If you
do the math from front to back the value of the B2 Pro
is verifiable in addition to the engineering details
and the valid design concepts. The B2 Pro is an out-of-the-box
race bike with proprietary technology that makes you
faster. You make sure the geometry fits you, build it
to your size specifications, position yourself and then
race it. If the frame dimensions match your body dimensions
everything you need to have an optimal race is in the
parts kit, from Dura-Ace to Zipp to Visiontech and with
the Felt exclusives like the Bayonet front end and the
hidden rear aero-brake. The 2008 Felt B2 component spec
and frame design make it a bike split excuse killer.
Older Felt geometry featured
more relaxed seat angles, longer top tubes and lower
Felt's new B2 geometry enables
much steeper seat angles.
Felt also did produce on
the much needed overhaul of their geometry charts. This
was likely a direct result of their “wait and
see” design introduction that was a year or two
fashionably late to the carbon fiber party. Dan Empfield
of Slowtwitch.com mentioned that Felt made three seasons
worth of improvements to their triathlon geometries
in only one season between ’06 and ‘07.
2007 was a proving ground year for the new Felt triathlon
geometry. Their experience with the top pros and age
groupers verified that the new Felt tri geometry works.
This was partially due to their experience watching
people try to fit 76 degree seat tube angle bikes. Kuota,
Quintana Roo, Trek and others couldn’t see fit
to pass the 76 degree seat angle mark that separates
the pretender bikes from the true triathlon geometry
bikes. Felt took a design cue from the success Cervelo
had with their variable geometry seat tube angles and
dual position seat post head and mimicked that idea
on the new molded carbon fiber B2 framesets. In addition
Felt went steeper in how a rider could position their
seat angle and shortened the top tubes to match average
and short torsos. The previous Felts were mostly optimal
on the longer torso-ed riders. Felt also went a step
further and raised head tube heights reducing the need
for headset spacers that make the appearance of a bike
look cobbled and affect the ability of a bike to maintain
good headset adjustment. In the case of the Bayonet
equipped B2 Pro, the headset spacers are completely
|Felt's variable geometry
seatpost provides a wide fit band, especially for short
torso (center) to average/long torsos. The new Felt B2 geometry
label (left) appears on all Felt B2's showing the extremes
of effective seat angle and top tube length.
Felt took the concept of size-specific geometry to a
new level by paying special attention to the hard-to-fit
smaller frame sizes using 650c wheels. These little frame
sizes in 48cm and 50cm are not gender specific bikes with
powder blue graphics and shorter handlebar stems to make
them so-called “women’s bikes” but valid
small geometry, high performance race bikes that fit many
smaller riders regardless of gender. These bikes don’t
care what gender you are, they only care how steep or
slack your seat tube angle needs to be to pedal and run
efficiently and how long or short your top tube length
should be to match your torso length.
|The new B2 features size
specific geometries and tube shapes. Note the extra seat
tube extension on the smaller 50 cm frame, the head tube
extension on the 48cm frame and the difference in top
tube thickness between a large frame size and small one.
Each frame size is individually tuned for optimum ride
quality and performance.
One of several noteworthy features on the 2008 Felt B2
Pro package is the Bayonet front end. Bayonet is designed
to achieve several design goals: Make the front end more
aerodynamic, make the front end stiffer and stronger and
make the bike ride better. We rode and maintained Bayonet
front ends for a year before we penned this opinion: We’ve
learned the Bayonet front end is a valid design with several
advantages. The Bayonet makes the front of the bike noticeably
more solid and secure. If you have ridden a triathlon
bike with aerobars and the front end seemed soft, insecure
and unpredictable the Bayonet front end will improve that
sensation. If you are a timid or unsure bike handler the
Bayonet will inspire confidence because you feel more
connected. If you do loop courses with frequent turns
or technically demanding courses then Bayonet will help
you negotiate the corners at higher speeds with greater
confidence and control. A Bayonet equipped bike also descends
with a more confident feel and has better front braking
due to the stiffer brake mounting point.
The Bayonet is about front end stiffness,
stability and control. I thought this bike climbs, steers
and brakes better than any triathlon bike with the added
strength and security of the unified B2 Bayonet front end.
An out-of-the-saddle effort is confident and exhilarating.
Steering inspires a feeling of safety, stability and sureness.
The bayonet is maintenance free and easy to make positional
The Bayonet front end works by reducing
the number of total front end components and integrating
them into fewer unified units making the entire front
of the bike stiffer. As a result there is basically
less to wiggle, less to flex.
A key challenge to moderating bike steering
is that the rear wheel is enclosed in a triangle on
the frame (the “rear triangle”) holding
it in good lateral alignment with the frame as the
bike is leaned over during a turn. The front wheel
is not in a triangle, supported by a single strut
on either side- the fork blades. As you lean into
a turn the front fork blades flex differently than
the rear triangle. The result is the steering gets
worse the harder you turn. The rear wheel is at one
lean angle while the front wheel is at another. Until
a rider corners long enough on the same bike to learn
this response it is an unsettling revelation. This
is part of the reason a new rider on a high speed
descent at Ironman Wisconsin, Ironman Lake Placid,
the Monaco 70.3 bike course or the Alcatraz bike course
might shy away from a flexible front end triathlon
bike. I would consider the Bayonet equipped B2 Pro
an advantage on technical bike courses like those,
even over a road bike front end. The bike simply handles
easier- it is like a car that is easier to drive.
Easier requires less energy. Less energy means either
more efficient or faster. Especially in longer events
the improved handling of the Bayonet front end could
be an advantage worth considering. There are also
the practical considerations of making it easier to
reach a gel pack in your back pocket or grab a bottle
while riding one-handed through an aid station. The
Bayonet front end makes real-world riding situations
feel noticeably more secure and steady. If you’ve
ever felt sketchy riding in the aero position and
reaching for a water bottle or gel pack then you understand
the need for the Bayonet front end.
Felt claims the Bayonet front end improves
front end aerodynamics. That is impossible for us
to verify even if we did have adequate wind tunnel
testing at our disposal. Felt did use extensive flow-analysis
and wind tunnel testing to develop and verify the
validity of the Bayonet’s aerodynamics. For
now, you either take their word for it or not.
The Bayonet uses its
own stem with adjustable rise angle. Three stem lengths
are supplied with each Felt B2 Pro so your bike fitter
can achieve the desired reach. A good Felt dealer
will have all sizes in stock from 80 mm to 120 mm.
Additionally the front portion of Oval’s adjustable
stem clamps to the Bayonet front end and has been
used by some Felt sponsored athletes who wanted a
stem alternative for additional fit options.
Some added practical benefits we’ve
discovered with the Bayonet front end on the 2008
Felt B2 Pro is that once the unit is assembled and
adjusted it never needs to be touched again. When
you pack the bike in a flight case you simply pull
the cockpit (aerobars and base bars) out of the stem
by opening up the front clamp. You never need to touch
the headset adjustment. For people who are worried
about assembling and disassembling their bike for
travel this is a big advantage. Another benefit is
that your handlebars can never be crooked. They are
held in perfect alignment with the front wheel once
the bike is assembled.
The entire Bayonet assembly remains intact for flight
case travel. This makes flying with your bike easier
Felt: Keep the aluminum base
bars, lose the "R" bends. We replace the
stock "R" bend aero extensions with ski
bends at the customer's request for better comfort.
The cockpit on the 2008 Felt B2 Pro
has valid improvements over 2007 including the FSA/Visiontech
aerodynamic brake levers. These are my favorite brake
lever. These levers were recently improved further
with a flatter grip area. Some manufacturers are specing
terrible brake levers on their highest end bikes.
Felt included a high end set of brake levers that
compliment the nice feel of the Bayonet front. Felt
further shored-up their cockpit by sticking with aluminum
Visiontech wing-shaped aerodynamic base bars. While
these are a few grams heavier than the newer carbon
fiber alternative from Visiontech they are half the
cost and much stiffer, adding to the overall confident
feel of the front of the bike. I’ve raced on
the carbon variation of this bar for a season now
including two half Ironmans and Ironman Wisconsin
and I can tell you I’d rather have the aluminum
base bars that come on the Felt. We don’t like
the carbon fiber Visiontech “R” bend aero
extensions that come out of the box on the B2 Pro
so we routinely swap them out for Visiontech’s
excellent ski bend variation of the same bar for better
comfort and ergonomics. We cut these bars to length
to fit the individual customer during their bike fitting.
The component kit on the 2008 Felt
B2 Pro is utterly straightforward: Everything that
counts is Dura-Ace. This isn’t a “mix”
bike; it is 2008 Shimano Dura-Ace 10 speed front and
rear derailleur, crank, brakes and shifters. From
the cranks to the brake calipers if a component has
a name on it the name is Dura-Ace. This means no upgrades
needed. We exchange the cranks for the right length
for each individual customer and adjust the gearing
for your “A” race and you are ready. I’m
pleased Felt used the more durable Ultegra chain on
the bike but would upgrade the cogset to Dura-Ace
from the Ultegra spec on the Zipp wheels and put the
Ultegra cogset on a pair of Shimano R-500 or Easton
Vista wheels for everyday use.
Straight spec: Shimano Dura-Ace
10 speed crank, derailleurs and brake calipers. Shifters
The wheelset that comes out of the box is 2008 Zipp
606 clinchers. This combines Zipp’s 58 mm deep
front wheel with their 80 mm deep rear for an excellent
all-around condition race wheel set that is at home
at Kona or at your local triathlon. These are the latest
version with dimpled rims. Since Zipp has been the preferred
wheel brand on the pier in Kona and at every major triathlon
Felt’s decision to ally with Zipp on the race
wheel spec was a good one.
When you buy the B2 Pro with Dura-Ace,
Bayonet front end and Zipp 606 wheelset as a package you
save approximately $1333.96 before tax and labor as compared
to buying the components, wheelset, Bayonet front end,
tires, handlebars and saddle separately to build the bike.
It is cheaper to upgrade up front with the complete bike.
That is the wisdom of buying the bike complete. This savings
is comparing the purchase of the component group at discount
mail order and the complete price of the bike at Felt’s
approximately $5800 suggested floor price.
binder collar on the new B2 Pro is durable and fully
replaceable should disaster strike. This is a big improvement
over other manufacturers' designs that can easily damage
a frame if stripped.
The details of the frameset include a reliable
dual binder bolt seat clamp that works best at 5 Newton-meters
of torque. Check to make sure both bolts have equal torque.
The design of the Felt B2 Pro seatpost binder clamp is more
impressive the more you think about it. Some other popular
carbon fiber triathlon frames feature a binder collar that
has bolts threading directly into the frame. If you strip
those threads inside the frame your frame has to be sent
back to the manufacturer. Felt's seatpost binder assembly
on the B2 Pro is completely replaceable for under $10 and
it commonly available at Felt dealers. The seatpost has
two positions and adjusts easily through a wide variety
of angles with four different saddles we tried including
Felt’s triathlon saddle (which is quite good), Fizik’s
Arione Tri, the Blackwell Flow, The profile Tri-Stryke and
Terry’s Women’s Triathlon Saddle. Index marks
for saddle height are printed on the side of the carbon
fiber, aerodynamic seatpost. The seatpost fit in the frame
Felt's variable geometry seatpost
and Carbon 3.1 Triathlon saddle.
One of the most unique
features of the B2 Pro frame is the missing rear brake.
The rear brake caliper has been moved from the traditional
seat stay mount to above the bottom bracket. This
improves frame aerodynamics. Estimates vary on how
much of an improvement this makes but the consensus
across manufacturers is that it does make a bike faster.
The rear of the bike is important from an aerodynamic
perspective since turbulent air is trying to re-assemble
behind the rider. The more smoothly and quickly it
can reassemble into calm air, the lower the parasite
drag and the more aerodynamic the bike frame. It would
be nice to attach a number to how much time this really
saves, but even Felt tells us that is difficult. This
is not a new design concept and has been seen on previous
time trial bike frame designs and is also used in
the 2008 model year by other manufacturers as the
new way to make a frame faster. It also may make braking
feel more responsive since the chainstays are stiffer
than the seat stays and the brake is now mounted on
top of those stiffer chain stays.
In addition to knowing
the advantages of the new brake mounting there are three
things to keep in mind: The quick release lever on the
rear brake caliper needs to be in the correct closed
position when pedaling or the crank arm will hit it.
I have no issue with this since you shouldn’t
ride with the brake quick release open anyway. Second,
you do want to be sure your right brake pad is correctly
aligned before installing the crank. Changing brake
pads will require the removal of the drive side crank
arm or chainrings. In a way, this strikes me as some
of the things you do to service a Ferrari, Porsche or
BMW. It’s a racing machine and has one or two
attendant racing technical idiosyncrasies. Thirdly,
if you are going to take advantage of the more aerodynamic
rear end then don’t use a behind-the-saddle bottle
cage mount or carry a big bag behind your seat on race
day. It’s fine in training but it will negate
most of the aerodynamic benefit of having a smooth,
aerodynamic rear end on the bike. Stick with a Profile
aero drink system in the handlebars and a bottle cage
on the seat tube. That is plenty to do Ironman.
Felt B2 Pro aerobrake moves the brake to the top of
the chainstay inside the seat tube. This improves aerodynamics
and braking stiffness. You do need to adjust your right
side brake pad before crank installation and remove
the crank/chainrings to change your brake pads, a bit
of extra work.
The massive rear carbon fiber wing
with tight fitting rear wheel cutout improve aerodynamics
along with the aerobrake.
Rear-facing horizontal dropouts with adjuster
screws facilitate wheel adjustment.
The mounting of the brake above the
bottom bracket is clean and even improves the ride
quality of the bike since the chainstays are oddly
“dropped” at their mount point to the
bottom bracket. It keeps the side-to-side stiffness
in the back but helps damp your sensation of vibration.
We wondered what would happen if you
dropped your chain to the inside of the crank accidentally
while shifting from the big ring to the small ring.
It struck us that there was a real potential for serious
chain suck or even frame damage if the chain somehow
got tangled in the brake near the bottom bracket.
Try as we might by intentionally dropping the chain,
nothing happens- the chain simply lands on the bottom
bracket shell better than most bikes without touching
the frame or brake. Impressive.
The rear triangle features another Cervelo-esque
design cue with rear-facing horizontal dropouts and
little dropout screws inside the dropout itself. These
little screws adjust the proximity of the rear wheel
to the aero cutout in the frame. With a 700 X 23c
clincher tire we simply removed the screws altogether
and the gap between tire and frame were perfect and
the alignment was straight.
Felt’s internal aerodynamic cable
routing on the 2008 B2 Pro sets the new industry standard
for best internal cable routing. I have no reservations
in saying this is the best in the industry on any
bike I’ve seen. This is an important mechanical
feature. Firstly, the brakes and derailleurs rely
on the smoothest movement of the cables through their
housings for best component performance. A common
cause of poor shifting and braking is bad cable routing,
abrupt bends in cable housings, internal frame members,
seams or remaining mold material from the manufacturing
process interfering with the free movement of cables.
Felt’s internal cables are fully guided through
smooth tubes that are individually labeled for front
and rear brakes and derailleurs. There is no trouble
installing a new cable through the frame- it can literally
be done the first time, every time, in seconds. You
can feel the results of this in smooth shifting and
braking regardless of how many times you disassemble
the bike for flight case travel. Compare this smooth
cable routing to most of the other internal cable
routing arrangements and you quickly understand how
valuable this feature is.
cable guides on the Felt B2 Pro provide the smoothest
functioning internal cable routing on any bike we've
seen. This is the new standard.
In the time it took us to review the Felt
B2 Carbon I rode the bike in many versions and configurations
including the 2007 B2 Carbon and the more exotic relative
of the B2, the Felt DA. The DA is shaped the same as the
B2 but uses different carbon fiber resulting in a lighter,
but more flexible frame. I ride the 52cm Felt B2 Pro with
an Oval 125 mm stem, 175 mm cranks, 270 mm Visiontech
ski bend aerobars with 1.5 cm cut off the ends to facilitate
better shifting. These are the type of alterations we
make for each individual customer for every bike we fit
and position. I use my favorite Time RXS pedals and have
actually stuck with Felt’s stock Carbon 3.1 Triathlon
I found the 2008 B2 Pro is an absolute
thrill to ride. Frame aerodynamics and the Zipp 606 wheels
make the bike fast out of the box. Shifting is always
relaible due to the excellent cable routing and spotless
component spec. The icing on the cake is the authority
the Bayonet front end gives you. The bike feels solid
and tough, steers with clairvoyant precision- you "think"
it where it wants to go through a fast turn. For a triathlon
bike, this corners better than any road bike I've been
on. At extremely high speeds it is stable and quiet. The
Bayonet makes hill climbing fun. We waited a long time
for Felt to develop their flagship carbon fiber triathlon
bike and it was worth the wait. It's difficult to say
enough good things about this bike and tough to find anything
wrong. The B2 Pro that came as our test bike got my name
decal put on it- I'm keeping it.