Bikesport Michigan Online - Review

We've been riding the Felt B2 throughout '07 before getting on the new 2008 B2 Pro.

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.

(left) 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 head tubes.

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 extinct.

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 adjustments to.

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 than ever.

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 too...

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.

The seatpost 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 is excellent.

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.

The unique 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. Nice design.

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.

The internal 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.