Atomik carbon goes big with Phatty 85 and Chubby 43 rims

Composite fat and plus rims claimed to shave weight, increase durability

Fat Bike Plus Wheels Winter Guide
Atomik utilizes a combination of aerospace grade foam and carbon to create a single wall rim that is durable enough for off road usage.

Atomik utilizes a combination of aerospace grade foam and carbon to create a durable single wall rim (click to enlarge).

Editor’s Note: This article is part of the Mtbr Ultimate Guide to winter mountain biking, fat bikes, gear, apparel, lights and trainers. We are taking a deep dive into all manner of cold weather mountain bike gear, with round-ups and reviews of fat bikes, tires, wheels, apparel, trainers and more. To see all the articles, head over to our Winter Guide Hub Page.

While many of the performance mountain bike rims on the market utilize a double wall construction to improve strength and durability off road, as well as increase stiffness, that design is not necessarily the best for fat or plus sized wheels.

Conventional rims blown up to fat dimensions would be extremely heavy and would leave more surface area exposed to impact. Enter Atomik, which claims to have created a carbon fiber rim that can withstand high stress and high impacts.

The shallow profile of Atomik’s single wall rims reduces exposure to impacts.

The shallow profile of Atomik’s single wall rims is designed to reduce exposure to impacts (click to enlarge).

Atomik’s solution is a single wall carbon rim that is wrapped around an aerospace foam core. The foam is molded into the structure, creating a pseudo-semi wall rim that boasts increased strength, energy dissipation and stiffness while adding additional damping characteristics. The rim itself is skinned with a blended 12k carbon fiber weave that is claimed to be impact resistant and lends additional protection and strength.

The Phatty and Chubby both benefit from an ultra low profile.

The Phatty and Chubby both benefit from a low profile (click to enlarge).

This design results in a low profile rim that helps reduce damage from trail debris and reduce snow and mud build-up on a wheel when riding in nasty conditions.

While no-name rims from overseas might be cheaper, the devil is in the details.

While no-name rims from overseas might be cheaper, the devil is in the details (click to enlarge).

This technology is now available in Atomik’s Phatty 85, which fits tires up to 4.8”, and the Chubby 43 which will accept up to 3.25” tires. The fat bike rims are available as a 26” only and have a 77mm inner depth. Each rim weighs 570g and a set will set you back $1,250. Prices for a complete with DT 350 hubs starts at $1,825.

The plus version is only available as a 27.5”, but Atomik claims it will fit on most existing 27.5 and 29er frames. Price for a set is $1,070 and complete wheelsets begin at $1,650.

For more information visit atomikcarbon.com.

Photo Thumbnails (click to enlarge)

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