We test the Felt B12 triathlon bike
Felt is one of the original tri bike brands and the choice of champions such as Mirinda Carfrae. The B12 offers a wide fit range in a comprehensive Ironman-ready complete bike package.
Frame and fork
While Felt’s cheaper B16 frame uses an older mould set, every ‘modular monocoque’ section behind the head-tube on the B12 is exactly the same shape as the company’s flagship DA family bikes. The UHC Performance grade fibre does mean a 20 per cent weight gain, according to Felt, which explains the 1,592g frame weight. Strength and stiffness is the same, though, and you get the same front and rear wheelhugger tube shapes, distinctive forward-hooked aero seatpost, alloy sleeved BB30 bottom bracket and full Shimano Di2 compatibility.
The rear facing dropouts get hidden wheel stop screws for accurate tyre clearance, and the rear brake hangs under the BB. Gear and brake cabling is all internal, and the chassis is compatible with the frame-filling triangular TorHans aero bottle supplied with Felt’s DA bikes. You don’t get the leading-edge bayonet fork of the DA bikes though, and while the frame has a stepped sync onto the trailing edge of the fork, the conventional front brake doesn’t have any draft-dodging advantages.
Felt is one of the few companies making XS sized aero frames. Developed directly with ‘Rinny’ herself, the smallest of the company’s six frame sizes comes with smaller 650c wheels to keep handling and position in proportion.
Felt matches its stem and crank lengths to frame size, too, which complements the narrow sizing bands for a really accurate fit. The own-brand 30mm-deep wheels and TTR tyres give the B12 a drag-reduction edge. The heavy, fat-armed FSA TT cranks never feel as stiff as they look, even with a BB30 axle, but the Shimano Ultegra gear mechs are a good spec at this price. The curious-looking Vision Metron shifters work really well once you’ve got the hang of them too, though ours rattled a lot on rough roads.
You can’t fault the amount of extension adjustment on the Felt bars though, and the pad width and fore aft position is easily changeable, too. You’ll need to trim the excess length down if you’re not going to smash your knees on them out of the saddle, however, and pad angle adjustment is limited. Not everyone appreciated the sticky gel pads either, but we’ve always been big fans of Felt’s Devox base bar with its integrated brake levers and little rubber hoods. The Prologo saddle is much more comfortable than it looks, too.
The more holistic complete bike feel definitely comes across in the ride, and while we’re used to riding whatever cranks and stem come on a bike, it was nice to have ones that felt just right. The kinked-forward seatpost position is obviously optimised for multi-sport use too, with a generously open pelvis angle that lets you stride – rather than stumble – off the bike in race or training-simulation situations. Comfort levels are good too, with most of the sting being sucked out of rough surfaces before it reaches your shoulders and shorts, without the frame feeling overly soggy.
While we haven’t got a wind tunnel to confirm or deny the exact drag data, the B12 feels clean and efficient in most wind conditions. The mid-section aero wheels certainly add speed sustain over slight rises or into gusting headwinds, and the
Felt feels PB-friendly straight from the shop. The whole bike feels significantly more ‘together’ than the previous B12 frame, and it’s stiff enough to cope with properly deep-section rims if you upgrade in future.
Upgrading rolling stock would likely improve handling too, as while the deliberately narrow spoke flange spacing may reduce drag, it definitely allows more sideways flex. The very short front end and narrow base bar can also make the B12 a duck-and-dive handful if you get too far forward out of the saddle. Cable routing out of the back of the extensions is likely to knock your knees with an early warning to sit down and settle down before you trip up.
Climbing is definitely not the strongest suit of the B12, though. Its 9.52kg weight is obvious straight away on inclines. While frame, crank and wheel stiffness are adequate to get things moving on the flat, you can feel the Felt twisting and undermining torque transfer as soon as you’re fighting a significant slope.
It takes its time out of corners too, and this combines with obvious wheel flex on entry to put the B12 at a definite disadvantage on twisty or rolling roads. Then again, Felt’s AR family provides a more versatile aero road option if that’s what you’re after, and the B12 does the long-haul, low-stress, finely fitted job it’s designed to do well.
+ Great frame fit, flattered with size-specific componentry
+ Smooth ride with noticeable wheel and frame speed-sustain
– Weight and frame/wheel flex dull dynamic performance
– Handling can be a handful out of the saddle