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Bird Forge review

Brilliant value full build

Our rating 
4.5 out of 5 star rating 4.5
GBP £2,900.00 RRP
Custom build / Frame only: £695 / $952 / €962
Pack shot of the Bird Forge hardtail mountain bike

Our review

Killer spec for the cash, all bolted to a lovely steel frame with an unshakeable shape
Pros: No compromises when it comes to the Forge’s totally contemporary geometry; unparalleled value for money on full builds; excellent ride characteristics, with comfort and control on all types of terrain
Cons: Frame-only price is higher than others on test; the flange of the DMR Deathgrips makes accessing the AXS upshift paddle tricky
Skip to view product specifications

Bird has received many plaudits, including winning our 2021 Trail Bike of the Year test with its Aether 9 full-sus. So when I heard there was a new steel hardtail mountain bike in its stable, I had to get one on test.


The upgraded SRAM Eagle build Bird sent me is outstanding value for money, especially when the Forge frame costs more than the others I had on test.

Bird Forge details

  • Selva service: Formula’s Selva is one of the most adjustable forks available. You can even change the compression damping circuit to suit your ride-feel preferences.
  • No wires: SRAM AXS wireless shifting is a steal at this price. You even get the updated shifter paddle, designed to mimic the brand’s mechanical shifters.
  • Pinch protection: Bird pre-fitted a CushCore insert in the rear wheel. This ring of closed-cell foam offers additional tyre support and helps prevent pinch punctures.

Bird Forge frame

This 29er frame is optimised for 140mm- to 160mm-travel forks and features Reynolds 853 DZB top and down tubes – arguably the two that most affect ride quality.

Elsewhere, Bird uses 4130 chromoly, with the thin-diameter tubing giving that classic steel hardtail look.

The brand has opted for an IS (International Standard) brake mount rather than the more modern PM (post mount) style, so you’ll likely need an adaptor for your rear brake. The thru-axle bolts into a SRAM UDH (universal derailleur hanger).

Other features include two sets of bottle bosses, external cable routing and an ISCG-05 mount.

Bird is known for its modern geometry, and the Forge is no exception.
Andy Lloyd / Immediate Media

Bird Forge geometry (based on 140mm fork and in sagged setting)

Bird is known for its modern geometry, and the Forge is no exception.

It has a 64-degree head and 77-degree seat tube angle, paired, on my large size, with a long 496mm reach and low 290mm bottom bracket (BB) height.

For ‘size large’ riders who don’t want such a long stretch to the bar, Bird offers a ‘Medium Long’ size with a shorter seat tube but still rangy 473mm front end.

Seat angle (degrees)76.876.876.876.8
Head angle (degrees)65.865.865.865.8
Chainstay (mm)430430435435
Seat tube (mm)395420445470
Top tube (mm)605630655680
Head tube (mm)100110120130
Bottom bracket drop (mm)87878787
Bottom bracket height (mm)290290290290
Wheelbase (mm)1183121012421269
Stack (mm)654663672681
Reach (mm)449473496518

Bird Forge kit

There’s a fairly wide range of parts customisation available. My bike was based on the £2,357.99 SRAM GX Eagle build, but had a Formula Selva R fork and Cura brakes, instead of the stock RockShox Pike Ultimate and SRAM G2 RSCs, plus sturdy DT Swiss rims rolling on Hope hubs, with a CushCore insert fitted in the Maxxis Dissector rear tyre.

What really stood out, though, was the upgraded SRAM GX Eagle AXS wireless drivetrain, which proved dependable, consistent and frankly excellent – especially for the money.

How we tested

We put four hard-hitting hardtail frames, which can be built up into complete bikes for around £3,000, to the test on some of the UK’s toughest and steepest tracks.

These UK-designed frames were ridden at our proving grounds in the South West, on the varied tracks of BikePark Wales and in the steep loam of High Burnside, near Aviemore in Scotland.

Smooth, stable handling is a must, but so is pin-sharp accuracy, so you can thread your way between trail features that might otherwise throw you off-line.

Also on test

Bird Forge ride impressions

With a similar-length front end to the Cotic BFeMAX and the same slack head angle as the Pipedream Moxie Mx3, it’s no surprise that when the going gets rowdy, the Bird comes back for more.

It inspires confidence on the steepest tracks and holds a line well when things get loose, aided by the BB height, which is so low I was glad of the bashguard when riding rock-rolls.

The Formula Selva fork has an incredibly plush initial stroke, separating you from trail chatter.
Andy Lloyd / Immediate Media

Cornering performance is also stellar. The distance between the tyres’ contact patches, the raked-out fork and the proximity of your heel to the ground when you drop the outside crank arm allow the Forge to rail berms and eke out grip on surfaces you’d normally pucker-up over.

At the same time, the 435mm stays mean it isn’t a chore to lift the front wheel over obstacles.

Front-end comfort is also good. There’s a hint of zing in the frame – not quite as much as on the Moxie, but enough to retain traction over off-camber roots and keep the bike tracking true in corners.

The Formula Selva fork has an incredibly plush initial stroke, separating you from trail chatter, and the Cura brakes are favourites, too, with a light feel and powerful caliper. Like the fork, they help keep your hands fresh when battering down bike-park tracks.

When the going gets rowdy, the Bird comes back for more. It’s confident on the steepest tracks and holds a line well when things get loose.
Andy Lloyd / Immediate Media

The Selva offers plenty of tuning options, too, with adjustable positive and negative springs, plus swappable ‘CST’ compression valves.

The 2.4in Maxxis Dissector tyres I chose shone in dry conditions, although compared to the 2.6in rubber on other bikes on test, they felt noticeably less comfy when rattling over really rough stuff.

On rocky terrain, the CushCore insert was a real bonus, allowing me to run a touch less pressure and saving the rim a couple of times.

I tried the Forge with the BFeMAX’s chunky rubber and had no clearance issues, so one of the 2.5in Maxxis tyres that Bird offers should work well.


My only kit niggle is that I found the flange of the DMR Deathgrips made accessing the AXS upshift paddle tricky, but Bird does offer other grip options.

Product Specifications


Price GBP £2900.00
Weight 13.8kg (L)
Brand Bird


Available sizes M, ML, L, XL
Headset Bird
Tyres Maxxis Dissector 3C MaxxTerra EXO TR 29x2.4in WT
Stem Race Face Turbine, 40mm
Shifter SRAM GX Eagle AXS
Seatpost Bird Down 200 dropper
Saddle Fabric Scoop Race Ti
Rear derailleur SRAM GX Eagle AXS (1x12) with MRP chain guide
Handlebar Race Face SixC, 780mm
Bottom bracket SRAM DUB
Grips/Tape DMR Deathgrips
Frame 4130/Reynolds 853 DZB steel
Fork Formula Selva R, 140mm (5.5in) travel
Cranks Truvativ Descendant carbon, 32t
Chain SRAM GX Eagle
Cassette SRAM XG-1275, 10-52t
Brakes Formula Cura, 180/160mm rotors
Wheels DT Swiss XM 481rims on Hope Pro 4 hubs