Readers outside of the UK may not be familiar with Bird bikes, and that's a shame because the British brand has earned a reputation for offering solid value and an innovative spin on the direct-sales approach. They ship internationally and are looking to set up demo partners outside the UK.
They started out in 2013 as a 27.5"-wheel-only bike company, but soon spread their wings to include bigger wheels. The Aeris was their first full-suspension bike in 2014, and now they're releasing the sixth bike to bear that name. Confusingly, it's called the Aeris 9, where the number relates to the 29" wheel size, not the design iteration.
Bird Aeris 9 Details
• Travel: 160 mm or 180 mm rear, 160-180 mm front
• Wheel size: 29"
• Adjustable geometry
• Customisable spec
• Internal or external cable routing
• Sizes: M, M/L, L, XL
• Reach: 457, 486, 515, 544 mm
• MSRP: From £1430 (frameset) or £2870 (full build)
Bird describe it simply as "an all-mountain machine with a bias towards gravity racing." That might be putting it mildly, though, because the bike pumps out 160 mm of rear wheel travel in standard form but can develop 180 mm with an optional linkage, can accommodate 160-180 mm forks and boasts adjustable geometry that can get pretty wild.
Cables can be run inside or outside the tubes, but alas, not through the headset.Frame Details
The Aeris 9 frame may look similar to Bird's 150mm-travel AM9, but it's an all-new aluminum tube set designed to cope with the stresses of 180 mm forks. Among other differences, the Aeris 9 takes advantage of SRAM's Universal Derailleur Hanger.
One feature that's easy to miss is a flip chip in the chainstay (Horst) pivot which simultaneously changes the chainstay length, BB height and frame angles.
The top-tube mounted shock can fit a large bottle even with a piggyback reservoir. An optional shock link increases the travel from 160 mm to 180 mm while using the same 65 mm stroke shock. There's little information about the kinematics at this point, but it's offered with both coil and air shocks.
Bird have gone big on sizing. With sizes going from Medium to XL, the Aeris 9 is aimed at riders on the taller part of the spectrum; keep in mind that Bird also offer 27.5"-wheeled bikes with Small sizes included. The Medium is recommended for riders around 168 cm (5'6"), while the XL is for those around the 194 cm (6'4") mark. With a 544 mm reach, the XL size might be best suited to those pushing two meters.
The above chart is for the bike with the short chainstay flip-chip setting and a 160 mm fork. In the alternate flip-chip setting, the chainstay length is 6 mm longer, the BB is 7 mm lower and the frame angles are 0.5-degrees slacker. Fitting a 180 mm fork will take about a further 0.8-degrees off the angles. In the short chainstay setting, the head angle goes from 64 degrees with a 160 mm fork to 63.2-degrees with 180 mm, but this could go to 62.7-degrees with the lower flip-chip setting. Simple, right?
In addition to all that complexity, the effective seat angle changes by size, from 77° in the Medium to 78.5° in the XL - that's in the steepest configuration of fork travel and chainstay setting.
Specs and Pricing
Bird take advantage of their direct-sales model to offer complete customisation of the parts and setup using their online configurator. Supply problems notwithstanding, you have a choice of almost all the components. The idea is you can get the bike you want from day one, without wasting time and money swapping parts to your tastes.
You can pick parts from RockShox, Fox, SRAM, Shimano, RaceFace, MRP, Hope, DT Swiss and Formula. You get a choice of Maxxis tires too.
By today's standards, the pricing is relatively cheep ... I mean cheap. The Aeris 9 frameset starts at £1,430 and the entry-level build starts at £2,870. Bird recommends aiming a little higher up the pecking order, though, suggesting a build with a SRAM GX Eagle drivetrain, SRAM G2R Brakes, RockShox Lyrik Ultimate fork and Super Deluxe Ultimate Coil shock, Bird Factory wheels, Maxxis Assegai tires and Bird & RaceFace finishing kit - for around £3,875.
Bikes are available to order internationally now at www.bird.bike
. Demos can be arranged in the UK at Bike Bothy’s stores in Pitfichie and Laggan, Glencoe Mountain and Bird's showroom in Eversley, Hampshire.