Comparing Carbon Fat Bike Build Weights

DURABILITY vs. WEIGHT vs. PRICE

When building a Fat Bike, there are three main considerations : DURABILITY, PRICE, and WEIGHT.

Our goal at RideFATbikes.ca, is to always build the strongest and lightest fat bike for any given budget. As such, Durability and Weight take priority in our bike builds over Price. Someone will always be able to beat our prices, but they will seldom be able to offer a stronger and lighter fat bike, for any given price point.

• What is “Build Weight”?

  • The weight of a completely built bike, minus the pedals, tubeless sealant, bottle cages, Garmin/phone mounts. This is the weight that manufacturers will (usually) provide in their bicycle specification descriptions.

• What is “Race Weight”?

  • The final weight of the bike, ready to ride or compete in a race.

What are “ASTM CAT” ratings, and are they important?

Yes, ASTM CAT ratings are probably the most important part of any successful bike design, and should not be ignored by the builder, or the customer.

• A bicycle’s ASTM CAT strength and durability ratings range from 1 (weakest) to 5 (strongest), and are assigned to all successfully tested frameset, wheelset and components of a bicycle. A bicycle’s intended use is directly related to the ASTM CAT ratings of its installed components.

• Details can be found at www.astm.org, or searching on the ASTM Classifications of Bicycle Usage document titled “ASTM F2043-13”.

How do you Categorize Durability?

We build all our Fat bikes to ASTM CAT 3/4/5 ratings. Many manufacturers build their Fat bike framesets to pass only ASTM CAT 2 test ratings, and then focus selling (house brand) frames and components at that level, which reduces the price of their bikes. We do not stock the lower-tier ASTM CAT2 framesets or components, as they tend to fail outside of sand and snow environments (see more details below).

RideFATbikes.ca goes a few steps further, so our bikes are rated durable enough to ride/race on more technical and challenging trails and terrain, in any weather condition, or season of the year. This translates to LESS WARRANTY CLAIMS overall (most times, no warranty claims for the lifespan of the frame, components and wheelsets).

EVERYONE saves time from dealing with a broken down bike, while you watch the snow fall outside and miss riding in the winter season, or that vacation trip you were planning, or seasonal race that you were training for.

(Warranty claims in 2022, can take 6+ months to replace broken parts). RideFATbikes.ca builds our custom Fat bikes with proven quality parts that experienced the least warranty issues, and are at least Trail / All-Mountain rated (ASTM CAT 3+).

Industry-Standard “ASTM CAT” Durability Ratings

ASTM CAT 1 = rated for road bicycle use only

ASTM CAT 2 = rated components and frames for road, gravel, sand and snow use only (majority of “big box retailer” carbon fat bike frames and carbon wheelsets fall into this category). This is the bare minimum acceptable rating for fat bike frames.

• Designed for winter use, or beach riding.

• Not designed for technical and aggressive singletrack riding

• Not rated for jumping

• Drops of 15cm (6” or less)

• light-duty rolling XC is the limit of the frame/fork’s design capability

• Some bikes in this category are NOT rated for suspension use. Installation of a suspension fork may void the warranty. Even worse, some frames in this category are not suspension-corrected, meaning that if you do try to install a suspension fork, it may hit the downtube when turning side-to-side, or, the geometry may be significantly affected (for the worse) by the addition of a suspension fork with a much taller AC height (Axle-to-crown height) than the “stock” rigid fork that came with the bike at time of initial purchase. Always ask the retailer if the Fat bike you are looking to buy has a suspension-corrected frame. If it does not, you can be assured the frame was designed pre-2015ish, and will not have the most ideal (comfortable) geometry or frame construction techniques. (Usually another red flag is a 2 year or less frame and fork warranty on ASTM CAT2 frames).

• Fat bike frames in this category may have weight restrictions of 230 lbs or less -> combined rider+gear+frame weight.

• (Close inspection of frame warranty may list a host of “conditional use” warnings that completely VOID the warranty, and elude to “catastrophic failure” and “serious injury or death” if bike is ridden “outside its intended usage”, including but not limited to operation in extreme temperatures, rider+gear weight limits, suspension use, trail use, competition use, etc, etc.)

  • AKA = this is not a serious 4-season fat bike frame/component/wheelset design if you like to ride hard and be competitive amongst your fellow riders. If your goal is a high-performing fat bike, you shouldn’t get drawn into these lower-priced designs and their “Crash Replacement” programs, if you can’t even ride this bike 4-seasons and in technical singletrack without worrying about a frame or “branded” component or wheelset failure, causing an extended warranty downtime waiting on replacement parts as the winter season rolls on by.

• Here is an example of a “CAT2” fat bike frame/component warranty : link : < Borealis Bikes > (all Borealis branded parts are declared in their warranty as ASTM CAT2, including the frame, fork, carbon rims, seatpost and handlebars.)

ASTM CAT 3 = Trail MTB rated, all-season, all-weather conditions.

(this is where the fun begins!)

• Jumps and drops are intended to be less than 61cm (24”).

• rated for 4-season use, in any weather condition.

• rated for suspension use (usually 60-120mm, dependent on the frame geometry and suspension fork selected -> frame size can play a big factor here!)

• ASTM CAT 3, is the standard by which we start all our Fat bike builds.

• here is an example of a “CAT3” fat bike frameset warranty : link : < 9:ZERO:7 bikes > (short and right to the point. This bike is built for high-performance, competition use, singletrack use, all 4-seasons of the year, no weather or temperature restrictions, no rider+gear restrictions, and it’s a winning design in the most grueling Fat bike races on the planet like the ITI Alaska).

• Carbon framesets in this category like the OTSO VOYTEK and 9:ZERO:7 LYNX, may cost a bit more, but they are designed to withstand the abuse and perform at the highest levels expected for a hardtail fat bike.

ASTM CAT 4 = All-Mountain rated components, designed for (full) suspension use, and very demanding technical trail use. Almost all the components we install on Fat bikes are rated to this level or higher - regardless if we are trying to save weight or not. This includes our Atomik Carbon and Derby wheelsets, and all carbon cranksets used in our custom bike builds.

• downhill grades on rough trails at speeds less than 40 km/h (25 mph), or both. Jumps are intended to be less than 122cm (48”).

• the FOES MUTZ v3 full-suspension Fat bike falls into this category (CAT 4), as well as ASTM CAT 5.

ASTM CAT 5 = DH-rated gear. This includes the FOES MUTZ full-suspension Fat bike frame / Mastodon PRO suspension fork, many Atomik Carbon wheelsets, and all of the Derby DH carbon wheelsets used on our long-travel suspension fat bikes. Top-level gear, the best of the best.

• extreme jumping; or downhill grades on rough trails at speeds in excess of 40 km/h (25 mph); or a combination thereof.

We build this level of quality into every custom Fat bike.

RideFATbikes.ca Custom Build Weights

9:ZERO:7 LYNX (carbon) = 21+ lbs

OTSO VOYTEK v2 (carbon) = 21+ lbs

STAGE 3 Custom Build Kits

SRAM AXS XO/XX Eagle (wireless 12spd) custom builds

• 21-23 lbs on average

• Carbon frame and fork

• (Top-tier components w/ carbon wheelset, crank, handlebar and seatpost)

• < Click here > for an example “STAGE 3 AXS XO” RideFATbikes.ca build spec

STAGE 2 Custom Builds Kits

SRAM XO1 Eagle (mechanical 12spd shifting) builds

• 22-24 lbs on average

• Carbon frame and fork

• (carbon wheelset, crank, handlebar and seatpost)

STAGE 1 Custom Build Kits

SRAM GX Eagle (wireless or mechanical 12spd shifting) builds

• 25-26 lbs on average

• Carbon frame and fork

• (alloy wheelset, crank, seatpost, w/ carbon handlebar)

• < Click here > for an example “STAGE 1 GX” RideFATbikes.ca build spec

MFG Carbon Fat Bike weights

vs.

Our custom build weights for :

OTSO VOYTEK and 9:ZERO:7 LYNX

— WINTER 2023 —

(last edit on 22-NOV-2023, with FX exchange rate of $1 USD = $1.40 CAD)

• links to MFG verified weights provided

• the highest-rated versions of each MFG’s carbon hardtail Fat bike has been highlighted, to make a fair comparison

• Our STAGE 1/2/3 custom carbon hardtail Fat bike builds usually run 3-9 lbs lighter than the competition’s best stock builds.

ASTM CAT 3 RATED FAT BIKES

ASTM CAT 2 RATED FAT BIKES

This is an example of Fat bikes that we do not sell, mostly due to safety concerns for our customers, who like to do a fair bit of extreme riding, competition racing, and/or expedition/adventure biking in adverse climates and terrain.

There are many Fat bikes out in the wild with only ASTM CAT 2 strength ratings, and most of their frame designs date back to 2015/16. “CAT2” Fat bikes were designed primarily for leisurely use in Sand and Snow conditions.

We will pick just one as an example, to show the difference in the expectations the manufacturer has for honoring their bicycle warranties, and conversely, what the acceptable riding conditions the owner is “allowed” to use their bike in, without potential damage or injury occurring due to riding outside “the bike’s intended purpose”.

Page Summary :

• Example of an ASTM “CAT2” fat bike frame/component warranty : link : < Borealis Bikes >

• Example of an ASTM “CAT3” fat bike frame/component warranty : link : < 9:ZERO:7 Bikes >

• Our STAGE 1/2/3 custom carbon Fat bike builds usually run 3-7 lbs lighter than the competition’s best stock builds, and are built as strong or stronger than the best they offer. All our custom builds start at ASTM CAT 3/4/5.

• Our design goals are high-performance, durability and safety first - that’s why we choose the OTSO VOYTEK, 9:ZERO:7 LYNX/TUNDRA and FOES MUTZ for all our fat bike builds.