Product details

Frame
Frame

Frame: Altera G21
Frame Sizes: 45cm,49cm, 52cm, 54cm, 56cm, 58cm, 60cm
Material: High Modulus Toray 800 Carbon Fiber
Color: Champagne / Custom Painting
Carbon Weave: UD
Groupset Compatible: Machine and Di2 compatible
BB: BB T-47 inboard bearing
- GRX crank: T47 BB inboard bearing for Shimano 24mm spindle size
- SRAM DUB / DUB wide crank: T47 BB inboard bearing for SRAM DUB
- SRAM GXP: T47 BB inboard bearing for SRAM GXP
BB Width: 86.5mm
Headtube: Straight 1-1/2”
Rear Dropout: 12*142 Thru Axle
Rear Derailleur: Hanger Universal Derailleur Hanger: (UDH) - Replaceable
Cable: Internal cable
Chainring: - Single: Max of 42t for normal crank spindle and 44t for wide crank spindle
Brake Fitment: Flat Mount Disc
Cable Routing: Internal
Bottle Mounts: 4
Mudguard Compatible: Yes
Cargo Rack Compatible: Yes

Fork
Fork

Fork:1 1/8" - 1 1/2", 12*100 Thru Axle
Fork Weight:480g

Option 1: With mount holes
Option 2: Without mount holes
Able to Customise for Dynamo cable routing

Seatpost
Seatpost

Seatpost Weight:95.2g (without clamp)
Seatpost Shape:Round (27.2mm)

Tires Compatibility
Tires Compatibility

Max Tire Width:700x53mm, 650Bx2.1” (single chainring setup)

Handlebar
Handlebar

Optional: H21 | ST1+H25 combo | H9

Handlebar Size:
 H21:
400mm, 420mm, 440mm
Stem Size: 80mm, 90mm/100mm/110mm/120mm

Handlebar Size: ST1+H25 combo:
400mm, 420mm, 440mm
Stem Size: 90mm/100mm/110mm/120mm

Handlebar Size: H9:
400mm, 420mm, 440mm
Stem Size: 90mm/100mm/110mm/120mm

Weight
Weight

Frame Weight: 
Champagne: 1170g(56cm)Raw1050g(56cm)
Limited Rider Weight:
125KG

Included in the Box

  • Compression End Cap*1

  • Compression Plug*1

  • Compression Ring*1

  • Headset Bearings*2

  • Handlebar Spacer*1

  • CH9 Computer Holder*1

  • Downtube BB Cover*1

  • Front Derailleur Housing grommets*1

  • Cable Spong*2

  • Storges*2

  • Saddle Clamp Set*1

  • Front TA Axle*1

  • Rear TA Axle*1

  • Seatpost Clamp*1

  • Front Derailleur Hanger Cover*1

  • Front Derailleur Hanger*1

  • UDH Hanger

Hear from the Experts

A Premium Chinese Gravel Bike In 2026

By Road.cc

Feels More Premium Than Most Western Brands

By Tom Bowers Cycling

Altera G21 Get Me a Top 10 at the National Championship

By Tom Bowers Cycling

Custom Altera G21 Build

By Crafted Cycles

How I’d Spend My Money on a Race Gravel Bike

By Nic Vieri - Bike Mechanic

AK47 Gravel - Yoeleo Altera G21 review

By Peak Torque

G21 Altera, the best gravel with endless capabilities

More storage, more flexible, more comfort, more control and more of everyhing. If G21 has the answer to your questions, the Alterra G21 has the answer and more.

View more

Cargar video:

Refined Gravel-Optimized Geometry

Slacker headtube angle, longer wheelbase, and a shorter stem come together for better stability and control on rough terrain—without the worry of toe overlap.

Integrated Storage Solutions

Internal storage compartments on the top tube and down tube (with a built-in bag) let you pack more gear for extended rides or simply stash a day’s worth of essentials directly in your frame.

Generous Tire Clearance

Supports up to 700x53mm or 650Bx2.1” tires (single chainring). From fast gravel to rugged trails, Altera adapts to the ride you want.

UDH Compatibility & Optimization

The Universal Derailleur Hanger (UDH) adds an extra layer of security and flexibility. Ride confidently knowing your derailleur and frame are protected, and choose any groupset you prefer with UDH’s universal fit.

Pro-Flex Seatpost

Now featuring a 27.2mm round profile, the Pro-Flex Seatpost quickly absorbs road buzz for improved comfort. The round design also makes it easy to switch to a third-party seatpost if desired—or even upgrade to a dropper seatpost. This change from the previous D-shaped configuration opens up more possibilities for every rider.

Re-Engineered BB Shell

A threaded bottom bracket made from bonded aluminum is now molded into the frame—offering perfect alignment, improved durability, and a lighter overall build for a smoother ride experience.

Flared Cockpit System

With a 15.2° flare and widths from 400 to 440mm, H21 CARBON INTEGRATED HANDLEBAR offers better control and all day comfort. Perfect for gravel, adventure, and aggressive terrain.

Top Tube with Storage | With Locking for Bottle Cage- Pick Your Own

Integrated or Stem & Bar Combo

Ride with H21, easy to install and hassle-free integrated handlebar, or with H25 and ST1, easy to adjust bar and stem combination that allows for freedom.

Handlebar Options

H21 Integrated

ST1+H25 Combo

H9 Integrated

Without Handlebar

Altera G21 Geometry

 
 
45
49
52
54
56
58
60
Size Recommendation
Rider Height
160cm-168cm
165cm-175cm
172cm-180cm
177cm-185cm
182cm-190cm
187cm-196cm
193cm-201cm
A
SEAT TUBE LENGTH(mm)
450
490
520
540
560
580
610
B
TOP TUBE LENGTH(mm)
510
515
536.4
551
566
577
592
C
REACH(mm)
373
373
379
383
387
390
396
D
STACK(mm)
512
531
549
566
586
611
640
E
HEAD TUBE LENGTH(mm)
79
98.5
107
134
145
171
200
F
SEAT TUBE ANGLE
75°
75.0°
74.0°
73.5°
73°
73.0°
73.0°
G
HEAD TUBE ANGLE
69°
69.5°
70°
70°
71°
71°
71°
H
BOTTOM BRACKET DROP(mm)
79
79
79
79
79
79
79
I
CHAIN STAY LENGTH(mm)
433
433
433
433
433
433
433
L
FORK RAKE(mm)
47
47
47
47
47
47
47
M
FORK LENGTH(mm)
401.5
401.5
401.5
401.5
401.5
401.5
401.5

FAQs

Please read our FAQs page to find out more.

Bottom Bracket Specs

Our G21 uses a BB T-47 inboard bearing. Choose based on your crank spindle size:
Shimano GRX Crank: T47 BB inboard bearing for a 24mm spindle.

SRAM DUB / DUB Wide Crank: T47 BB inboard bearing for SRAM DUB.

SRAM GXP: T47 BB Inboard bearing for SRAM GXP.

Chainring Options

Single: Fits up to 42T for standard cranks and up to 44T for wide crank spindles.

Double: Accommodates a maximum of 50-34T with a BB to Crank washer.

Tire Compatibility

The G21 accommodates a 53c gravel tire or a 2.0 MTB 29 tire. Select the right tire to enhance your ride's performance and comfort based on the terrain you're tackling.

Fork Customization

Opt for a fork with mounting holes for front panniers or choose a seamless fork for improved aerodynamics.

Stem and Handlebar Combo

Yes, you can use a stem and handlebar combo. We recommend our ST1 stem with the H25 handlebar for a seamless integration.

Didn’t find your answer?

Don't hestitate to contact us

Frame Size
Frame Size: 45cm