Bird Aeris AM Profile Shot


Words by Robert Johnston | Photos by Sam Howard

UK-based Bird Bikes have been offering excellent value bikes with progressive geometry for many years at this point, but they’ve yet to see a real breakthrough internationally. They’re hoping that the new Aeris AM will change that, thanks to its lightweight carbon fiber frame with 160mm travel and very clean lines. Bird was kind enough to let us get on board the new Aeris AM before just about anyone else, and it’s been a serious amount of fun to test. Keep on reading or watch the video to learn all about it.


• 160mm Horst Link Suspension
• HTA 64
• STA 77.5 (effective)
• REACH 475 (R3 – ML)

Price: £1,995 (Frame / Shock)


The Aeris AM is Bird’s first longer travel enduro bike made with carbon fiber, and is Bird’s most advanced carbon frame to date, tipping the scales at 2.6kg and with builds possible from a claimed 12.6kg. The 160mm of rear wheel travel is designed to be efficient enough to support long pedaling missions yet offer hard charging capabilities, and can be paired with a 160mm or 170mm fork to tailor the handling preferences to each rider. As standard the Bird Aeris AM will be supplied with 29” wheels on both ends, but the flip chips in the Horst Link chainstay pivots allow riders to easily adapt the frame to run a 27.5” wheel with the same geometry aside from a shorter chainstay length.

FRAME AND FEATURES | The low-slung carbon fiber frame of the Aeris AM has plenty of room in the front triangle for a large water bottle on all sizes and an additional tool mount near the head tube, giving lots of standover clearance without sacrificing on convenience. The main frame pivots use locking collet axles to prevent loosening when riding, and the pivot next to the bb is also given double lip seals to keep water and crud out. All of the frame pivot bearings are warrantied for life, reducing maintenance costs should they fail in the long run. The downtube comes with a generous guard by the bb as well as a shuttle guard up towards the head tube, helping to keep it safe from harm.

There’s a threaded bottom bracket with ISCG05 mounts; 180mm post rear brake mount; and clearance in the rear triangle for up to a chunky 2.5” tire. Cable routing is internal in the front triangle (external on the chainstays) with clamped ports throughout and rubber shrouding to reduce rattle; and there’s a port on the downtube to allow for easy access to the cables to ensure routing is stress-free. The rear dropout is SRAM UDH and Transmission compatible, letting you run any derailleur system.

SUSPENSION | The Aeris AM uses the same Horst Link suspension system as their other full suspension bikes to deliver its 160mm of rear travel. It’s designed to offer good pedaling support across the cassette, with leverage ratio progression that’ll offer good early stroke sensitivity and end of stroke support with either an air or coil rear shock.

GEOMETRY | Bird has moved to a new “Wingspan” geometry system, which refers to their low standover and seat tube lengths allowing for riders to choose their ideal frame size based on its reach. There’s a choice of five frame sizes on offer from R1 (S) to R5 (XL), with the R3 size offering a “medium long” choice that avoids average height riders from being stuck in between two frame sizes. Between the dual-29er or mullet (29” front and 27.5” rear wheel) setups, geometry remains constant aside from the chainstay length, and there’s no size-specific rear ends featured on these frames – it’s 429mm for the 27.5” setting, and 440mm for the 29”.

The head tube angle is 64 degrees across all sizes, while the effective seat tube angles get progressively steeper through the size range from 77 degrees on the R1 through to 78.5 degrees on the R5. Reach numbers are quite typical for an enduro bike this year but size gaps are fairly small at 25mm, so there’s a range from 425mm to 525mm, which are paired with fairly low 618mm to 645mm stack heights. The bottom bracket height is 340mm, which equates to a 30mm bb drop. The size R3 (M/L) tested has a reach of 475mm, stack of 627mm, and wheelbase totaling 1,252mm.

Bird Aeris AM Geometry

BUILD SPECS | To begin with, Bird is selling the ML size (tested) or will take pre-orders on other sizes in the range which they’re expecting to deliver at the start of 2024, depending on frame arrival dates. They’re offering an early bird price of £1,995 / $2,495 including the RockShox Super Deluxe Ultimate RC2T rear air shock and a custom-made frame storage bag (UK only). Full builds will be made available shortly, with Bird’s custom bike builder letting you tweak the components package to your liking to allow for you to obtain your dream setup within your price range. Currently the frame is only being offered in black, but two more color options will be made available soon and customers will be able to change to their desired color before delivery.

Bird showcased a super lightweight XX-SL Build when they first launched the bike, with a weight of just 28.8lbs (13.06kg) and price tag of a rather reasonable £5900. Our build tested was an even more wallet-friendly offering, which we then added a couple of alternative test items in the form of the Nukeproof Horizon Pro alloy wheels and VEE tires with burly casings, and the total weight still came in at a very respectable 32.14lbs (14.6kg), up from the 31.4lbs (14.25kg) build provided with carbon Stans wheels and Schwalbe tires.

Bird Aeris AM turndown


SETUP | My time on board the Aeris AM was not extensive at just under 2 weeks, but I managed to get it onto a variety of terrain in this time across Scotland to get a good feel for it and play with the setup a touch to get it feeling about right. Pulling it out of the box, its low weight was immediately apparent, and confirmation of this fact when reading that 32.14lbs number on the scale – after I’d added a burly tire combo and alloy wheelset – had me very impressed. This number comes with a realistic, usable build, and though there are definitely areas where it loses in ultimate hard charging capability to a burlier build, it proved to be well up to the task for some aggressive riding.

Sag markers on the RockShox suspension made it easy to get air pressures dialed in, and the only concern I was left with was the height of the front end. A relatively low stack height combined with the low Race Face Next bars meant my front end height was on the uncomfortable side, but it was easily remedied by a higher bar. Suspension feel out of the box was on the fairly heavily damped side, which is typically my preference but did lead to some mild fatigue from a high level of feedback on the first descents, so I backed off the damper settings a touch and ended up in a comfortable spot.

Bird Aeris AM Climbing

CLIMBING | Seated position on the Aeris AM is comfortable, if a little more relaxed than some if you’re a long-legged rider like me due to the slacker actual seat tube angle. Even so, it took some very steep terrain before this caused any issue, and otherwise left me in a fairly happy spot, with the short-to-mid length rear end keeping just enough weight through that front wheel without actively having to lean all my weight through the bars. The pedaling platform is firm but not extreme, erring on the more efficient side than the traction-rich, but it still proved to offer ample comfort and purchase on slippery and rough terrain when combined with some relatively sticky rubber out back. The geometry strikes a nice blend that retains a healthy amount of agility to navigate tight uphill switchbacks, and when combined with its low weight the overall notions are very much that of a long-legged trail bike as opposed to a burly enduro bike when you’re on your way up the hill.

Bird Aeris AM cornering

DESCENDING | With the firmly damped initial suspension setup, there was a considerable amount of trail feedback coming through which carried on the long-legged trail bike notions from  the way up. However, upon playing with the setup to increase off-the-top compliance without reducing end-of-stroke support, I got the Aeris AM into a happy place where it simply felt like a light and tight enduro bike, and a dialed one at that. Between the effective cable management and healthy levels of chain slap protection, the Aeris AM was very quiet and free from vibration, which translates into a more comfortable and reassuring ride when you’re pushing hard through rough and rugged terrain.

The agility from the way up the hill is still somewhat present on the way down, making the Aeris AM a well-managed bike for less aggressive descents and flow trails. The weight reduction compared with many of the bikes I’ve been testing recently makes a notable difference to its manners through the tighter terrain or when popping and playing, with an extra notch of fun factor and reduction in energy expenditure all round. When things get a little gnarlier, it’s still a healthily capable bike, but it tends towards the slightly livelier side of things instead of being the most planted and stable machine that begs you to point it in a straight line through the gnar and hold on. The Bird Aeris AM instead benefits from a slightly more delicate and deliberate touch, but will still support through hard compressions and tire ripping berms without flinching all too often.

FINISH AND VALUE | Straight away the Aeris AM looks like a step up in quality and refinement over previous Bird bikes, with some killer lines in the carbon frame and a neat finish all round. This carried onto its on-trail performance, where it was tight and quiet, and aside from the downtube guard beginning to peel a little, there were no issues or loose bolts to complain about throughout testing. With the frame coming in at sub-£2k with a high quality shock, it represents impressive value compared with the vast majority of bikes these days, and I imagine the full builds will continue to set somewhat of a benchmark for value for money as this is where Bird has scored very highly in the past.

The Wolf’s Last Word

The new Bird Aeris AM is a great all rounder that offers a high quality finish at a reasonable price. It’s not a pointed machine that’ll excel in any one particular area, but strikes a nice balance of low weight and climbing efficiency with reasonable capabilities to tackle enduro terrain without flinching. Consider me impressed overall.

Price: £1,995 (Frame / Shock only)
Weight: 32.14lbs / 14.6kg (as built)


Frame: Bird Carbon | 160mm
Fork: RockShox Lyrik Ultimate | 160mm
Shock: RockShox Super Deluxe Ultimate 230x65mm

Brakes: Formula Cura, 200F/180R rotors
Handlebar: Burgtec Ride High 50 35mm | 800mm | 50mm Rise
Stem: Bird CNC Aluminum 35mm | 40mm Length
Headset: Sealed
Seatpost: Bird Down Dropper 200mm
Saddle: Ergon

Wheelset: Nukeproof Horizon Pro
Front Tire: Vee Snap WCE MK2 | GXE Core | Full 40 | 29″ x 2.5″
Rear Tire: Vee Attack FSX | DH Core | Full 40 | 29″ x 2.5″

Bottom Bracket: Shimano
Cassette: e*thirteen Helix Race | 12spd | 9-52T
Cranks: Shimano XT | 170mm
Shifter: Shimano XT | 12spd
Derailleur: Shimano XT | 12spd

We Dig

Light and Efficient pedaler
Quality finish and killer looks
Reasonable value
Fun balanced descender

We Don’t

Not super stable
Slightly relaxed climbing position for me


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