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Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity Bullseye Monster 26
Gravity

Gravity Bullseye Monster 26" Fat Bike Frame Fork Kit

★★★★★5.0 (3 reviews)

Start your fat bike build with a complete 6061 aluminum frame, CrMo fork, and essential components for 26x4.0 tires.

$199.00*
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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Gravity Bullseye Monster 26" Fat Bike Frame Fork Kit provides the foundational components for building a custom fat bike. At its core is a 6061 aluminum alloy frame engineered with 170mm symmetrical rear spacing to accommodate fat bike hubs and wide 26 x 4.0-inch tires capable of handling snow, sand, and loose terrain. The included rigid fork is constructed from CrMo steel, offering strength and natural vibration damping that complements the frame on rough surfaces.

Beyond the frame and fork, the kit bundles several essential components — a headset, stem, seatpost, and seatpost clamp — giving builders a head start on their project without needing to source these parts individually. The 135mm front hub spacing pairs with the CrMo fork for compatibility with a range of fat bike front wheels. This kit is aimed at cyclists who enjoy building bikes to their own specifications, allowing full control over the drivetrain, brakes, wheels, and finishing components that complete the ride.

Key Features

Aluminum Frame with Steel Rigid Fork

170mm rear spacing 135mm front spacing

Will Accept 26 x4.0 Tires

Seatpost and Seatpost Clamp Are Included

Headset and Stem are Included and Installed!

Specifications

Brand
Gravity
Model
Bullseye Monster
Frame Material
6061 Aluminum Alloy
Fork Material
CrMo Steel
Rear Spacing
170mm symmetrical
Front Spacing
135mm
Tire Compatibility
26 x 4.0 inches
Included Components
Frame, Fork, Headset, Stem, Seatpost, Seatpost Clamp

Pros & Cons

👍 Pros

  • 6061 aluminum frame is lightweight and corrosion-resistant
  • Kit includes headset, stem, seatpost, and clamp, reducing the number of separate purchases needed
  • 170mm rear spacing accommodates standard fat bike wheelsets
  • CrMo steel fork provides durability and vibration dampening on rough terrain
  • Compatible with widely available 26 x 4.0 fat bike tires

👎 Cons

  • Rigid fork only — no suspension included for rough trail comfort
  • Requires significant additional components to complete a rideable bicycle
  • 135mm front spacing is narrower than the 150mm standard used by some fat bike forks and wheels
  • Frame kit does not include wheels, tires, drivetrain, or brakes
  • Limited information available on frame geometry and sizing options

Frequently Asked Questions

The kit includes the Gravity Bullseye Monster frame, a CrMo steel rigid fork, headset, stem, seatpost, and seatpost clamp — the core components needed to begin a fat bike build.
The rear spacing is 170mm symmetrical, which is a common fat bike standard compatible with a wide range of fat bike rear hubs and wheelsets.
The frame and fork are designed for 26 x 4.0-inch fat bike tires, which is a standard fat bike tire size for all-terrain and snow riding.
The included fork is a rigid CrMo steel fork. If suspension is desired, a compatible aftermarket fat bike suspension fork with 135mm front spacing would need to be purchased separately.
You will need wheels, tires, a drivetrain (crankset, bottom bracket, chain, cassette, derailleurs), brakes, handlebars, grips, and pedals to complete the bicycle.

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