2018 FATBACK BIKES - STACK AND REACH v1.2 cover.jpg
2018 FATBACK BIKES - STACK AND REACH v1.2 cover.jpg

RideFATbikes.ca - Fat Bike Stack and Reach


RideFATbikes.ca - Fat Bike Stack and Reach

RideFATbikes.ca Logo - custom built Fat Bikes in Canada



Hard Tail (HT) and Full-Suspension (FS)

Copyright (C) and Trademark (TM) RideFATbikes.ca 2016-19

Reviewed by FAT-BIKE.com on 7 JAN 2017

The following STACK and REACH research article, including our custom sizing Charts, was reviewed by FAT-BIKE.com, in their FAT CAMP Tech Talk Show (on pod cast #19, aired January 7th 2017).  

You can listen to that pod cast, while reading this article, by clicking << Here >>.  The FAT-BIKE.com review of our website starts at 24min51sec and continues for about 8 minutes.




RIDEFATBIKES.ca created this web page to share information with the world-wide Fat Bike community, to assist all riders in getting fitted to a proper Fat Bike, regardless of BrandWe have collected this information from over 6 years of Industry testing and reviewing Fat bikes, during all 4 seasons of the year.

" HAVING TESTED OVER 70 Fat bike designs by SUMMER 2019, inclusive of many different manufacturers, component setups, using many different suspension and wheelset/tire configurations, there are very clear choices that offer exceedingly good geometry, handling, and values for the money. "

"Our driving force is to advocate for the sport and help riders find the best fitting bikes and gear, so they have the best experience with the sport of Fat Biking, and it becomes a new pass-time for everyone all 4 seasons of the year."


For Examples of our Fat Bike Suspension reviews, click here :



2019 STACK and REACH

Let’s get right to it… here are the updated STACK and REACH Fat Bike geometries for model year 2019, of the leading Industry brands sold in North America.

(We have removed the overseas OEM “badge-engineered” brands from the list. They can be found in the legacy geometry charts for 2016-18, as shown later in this article.)


Consumers in the market for a new fat bike, commonly ask the following questions :

“What is the most important factor to me, in buying a new fat bike” : Price? Aesthetics? Geometry? Componentry? Resale value? Upgrade-ability? Warranty? Weight? Tire Size compatibility?

Warranty and Durability : investigate what the warranty policy is, and how well the manufacturer honors that warranty. Also try to figure out how long that product tends to last before it needs to be replaced. Frame cracks, wear item failures like bearings, tires, seals, chain, crankset…the list goes on.

Upgrade-ability : If the bike you are looking at can’t be easily upgraded to current or emerging componentry trends, then maybe it’s not worth investing in (for example : QR hub standards vs Thru-axle, straight steerer tubes vs tapered, outdated 9-10 drivetrains vs 12spd+).

Resale Value : How well does a particular bike brand hold its value, and how often are owners willing to offer them up for sale? (short term vs. long term ownership). Generally, the tougher is it to find one of these bikes for sale on the used bike market, the stronger the ownership retension is. Both can be indicators of resale value. Tough to find bikes tend to hold their value, while a saturated brand secondary market may indicate some type of issue with that particular frame/build.

Componentry : To what level are you willing to go to get the latest and greatest gear? What do you value most, and what is worth most for you to invest your budget in? (drivetrain, wheelset, suspension, frameset, etc)

Aesthetics : Almost everyone wants a good looking bike to ride, but do you value its cosmetic looks, over its performance capabilities?

Tire Size : Always good to look for fat bikes that can accommodate the largest selection of both wheel diameter (26”, 27.5”, 29”) and tire size widths (3.8 up to 5.05”). A Fat bike frame limited to 26x4” or 27.5x3.8” wheelsets and tire specs is missing out on a lot of the fun of owning a fat bike, that can say, handle 26x4.8”/5.05” or 27.5x4.6” wheelset and tire specs. Especially in ungroomed, loose terrain.

Weight : Everyone wants a lighter bike. Flip-side is Price and Durability. If you want a bike to get continuously lighter by changing components, then the price will start to climb to maintain the same durability while reducing weight. At some point, you WILL be sacrificing durability (and in many cases, performance too) in order to save weight. It’s a balancing act of the scale and the wallet.

Geometry : RideFATbikes.ca feels this is the most important factor, when beginning the buyer’s journey. If the bike you intend to buy, does not fit well, no matter how good the deal, or the bling factor of the components, or the price, it just is not worth purchasing, if the frame geometry is not optimal - because you cannot modify the frame - you are stuck with its geometry once you buy it, for better or for worse. Some bikes clearly fit better than others, and perform better than others. Geometry should be your initial building block from which you design your next Fat Bike.


When I was searching for my first fat bike, many years ago, I had to chase down all sorts of random marketing information online, crunch the pricing and geometry numbers, consider the luring advertisements and the marketing of different frame colours, seeking the "right fit" and the "right bike". At some point, I finally happened upon what was the most important item I needed to resolve in order to buying my Fat bike. It was a specific geometry spec that not many Fat bike manufacturers published at the time.

So, I started calling those manufacturers, asking them for this information. While some readily provided it, others had no clue what it was. Hence, the STACK and REACH database was officially born at RideFATbikes.ca. Since that day over 6 years ago, our internal STACK and REACH database has turned into a fantastic way for us to custom fit and size riders to their Fat bikes, as it contained many thousands of data points, across over 440 different Fat bike frames. Hundreds of hours has been spent in its initial creation, along with its yearly updates. This database has been accurate for riders from 5ft-0 right up to 6ft-6, to match the heights the frame manufacturers designed the bikes for. Outside of these numbers, you may want to contact a custom bicycle frame welder to design a fat bike that will fit you best. There are a few very good options in Canada and the USA.



Another unique ability of our internal Stack and Reach database, is to pick out anomalies in some frame designs, that even the manufacturers were not aware of, until we contacted them - and they confirmed the issues after testing the data. Another unique feature is the ability to track many OEM frames back to the overseas factories where the frames are made, alongside other “badge-engineered” brands. This gave us the insight into how many Brands are interrelated, and which brands were picked from a catalog and rebadged once they landed in North America. (Unfortunately, we also found out that sometimes when a company says “Made in America”, they only technically mean “Painted in America”).

Ordering OEM Catalogue brands direct from Overseas

For example : Google the “FM190” and the “CS197” carbon frames. Compare their frame geometries and Stack and Reach numbers, and you will be able to pick out over 15 different fat bikes companies that share the same frame geometry, with only very minor tweaks, to the open mold design. Basically, this FM190 design started with one company paying investment costs for the mold (and potential R&D testing), then it was copied by several other companies, and then badge-engineered to many more US-based companies. Then a second version of this frame was released as the CS197 (because the FM190 had frame crack issues in the seat tube), and the CS197 can be easily spotted by its adjustable rear axle, that can be pivoted to change between two static chainstay lengths. This frame for instance, may cost twice as much state-side after its painted and “badge-engineered”, then it would cost direct from China. Other examples are the CS-001 and the SNO4 full suspension carbon frames, that initially copied the original Salsa Bucksaw design. Possibly an example of Intellectual Property (IP) theft, possibly not. Only QBP knows the answer to that one, as they discontinued the Bucksaw several years ago.

We did long-term testing on the overseas OEM frames noted above and found two interesting things. 1 - the OEM manufacturer produces updates to the frame at random intervals (be it routing mods, tube mods, accessory part mods, etc), and the end-user does not always know which version they have, at any given time. 2 - when something fails and needs to be replaced, then you will find out what version of the frame is, as the factory will ask for pics of what went wrong, and offer a band-aid solution, or a crash replacement upgrade. (You don’t usually get free frame replacements and you also have to pay import and air freight fees from Taiwan or China - that can get really expensive). This is when it can be beneficial to buy the same frame from a “US-based” reseller. They call themselves “manufacturers”, but in reality they are really state-side distributors for that frame, with their own decals. Either way, buying an OEM-catalog frame may be more cost effective ordering direct from Asia, but you may need to look at each purchase as a throw-away item, and also consider that small carbon manufacturer in China is using customers in North America as their R&D backbone.


If you want to support a North American manufacturer that went through the experience of designing, stress-testing, and distributing their own bikes - you invest your money back into the same Country. You also gain the benefits of things like : better frame warranties, more durable paint applications (that usually peel, crack or chip less often), the most modern geometry and componentry standards, higher resale value, and usually a longer term ownership.

RideFATbikes.ca proudly supports USA and Canadian manufacturers that design, test, and source their parts in-house, as much as possible, to support our local economies, creating a stronger tech base and job market, in our two neighbouring countries.


STACK and REACH measurements are by far, the two most critical sizing aspects to consider in finding the right bike for any given rider.  

NOTE : There are many other important secondary factors too, like BB (Bottom Bracket) drop, HT (Head Tube) angle, ST (Seat Tube) angle, and definitely C/S (chainstay) length.

Options like colour, Brand Name on the down-tube, and price, are basically irrelevant, if you can't find a Fat Bike that will properly fit you and accommodate to your riding needs.  

You will be throwing your money away on bikes THAT DO NOT FIT WELL, and likely to put them up for resale on the secondary market after only owning them for one season or less.

Chasing colours, decals and "deals" will amount to you never fully realizing the potential enjoyment and performance in the sport, if you opt to buy the wrong fitting bike, because some advertisement told you to buy brand "xyz", or you liked the colour of a certain Fat Bike, or just because a company makes well-known road bikes, that does not mean they spent the time, effort and engineering on designing a great Fat Bike.

As you journey through this process, hopefully you will notice that some manufacturers have dedicated their entire business model to the creation and improvement of Fat bikes. They are Fat Bike subject matter experts (SME’s).

There will no doubt be sponsored riders reading this article, and also individuals that are extremely "brand-loyal" to their CX/Gravel and road bikes.  Staying loyal to those brands may be admiral, but it may not get you fitted into the best performing, quickest and most comfortable FAT BIKE.  While your opinions may be "biased" towards a brand because of loyalty or required sponsorship commitments (and we understand that), our research has brought us to the conclusion that some FAT BIKES are just flat-out designed, built and configured better than others.

Things to consider :

  • Some FAT BIKES are suspension corrected for all the leading industry suspension forks. Some are not.

  • While some FAT BIKES are all-mountain rated, and can take on almost any terrain you throw at it, others are rated for only a 2-foot drop (or less), and the frame warranty is voided if you even add a suspension fork to it! (several major brands have these limitations)

  • Some frames are fabricated with superior carbon material, tube shapes, and bonding processes, resulting in lower overall weights, and at the same time, providing improved handling, rigidity, and higher strength-to-weight ratios.... while some frames just advertise a "lower weight" but can't be used for much outside of riding in the snow on double-track groomed trails.

  • The latest FAT BIKE frame designs can usually accept the latest componentry and wheelset/tire designs, including hub and suspension breakthroughs. This separates them from all the other frames on the market. Both in component compatibility and ride performance. For more information, click < HERE >.

  • In direct relation to "STACK and REACH" fitment, you also need to consider other important factors such as C/S Chainstay length, Bottom Bracket Drop, Seat tube and Head tube angle, for the best fitting and performance handling FAT BIKE, for whatever dedicated terrain you wish to ride on. (We are currently working on this topic as a separate review article).

 STACK and REACH Explained

OK, so what the heck is STACK and REACH..?  

With Stack and Reach, you have no need for :

  • "SM, MD, LG" or "15, 17, 19, 21" sizing techniques.

  • ignore ETT (effective top tube) and HT (Headtube Height).

STACK and REACH will replace all those "traditional" systems of categorizing frames, and it will standardize the cycling industry, not just for Fat Bikes, but for all bikes.  (Currently, I think it's most widely depended on, for Time Trial and Triathlon bikes, but it applies to Fat Bikes too!)

(Note : We first published this article and our Stack and Reach charts back in 2016, when these geometry-specific specs were not a widely published item for many brands. It required us to call and email repeatedly to acquire this information. Sometimes to no avail. Now in 2019, just 3 years later, Stack and Reach has become a staple for the brand geometry charts of all the major players in the Fat Bike industry.)


Information Required for Proper Frame Fitment

It is best to start out this process by getting the data on two sources of information :

  1. Knowing the Stack and Reach numbers of your existing Fat Bikes, or best fitting MTBs that you ride.

  2. Having a Personal Custom Fit Assessment completed.

Most cycling and training centers can perform this fitment test for you.  There are even some free "do-it-yourself" Fitment guides online.  The idea is to have a really good understanding of your body dimensions.  These include (but not limited to) : Inseam, Forearm, Thigh, Lower Leg, Trunk, Sternal Notch, Total Height, and riding style (AM, XC or Adventure/Excursion).

Once you have all these frame and body measurements, they will accurately record your personal data on how your body would best fit on any type of bike.  

For each type of bike, Stack and Reach numbers are combined with other critical frame geometry specifications, to arrive at the optimal frame configuration, for your cycling terrain and intended usage.

Why is it helpful to know your existing bike's stack and reach numbers?  Because with this information, you can envision how a new bike frame is going to "fit" in relation to what you already have... and you can "fit" this bike into your riding style... be it more downhill, XC, snow-based trekking, or some other race geometry.  Some need a longer reach to the bars to be able to move their center of gravity around on the bike... while others may want a taller stack, so the front end is higher up than their previous ride.... or, some racers may want the opposite, to lower the front end and get into more of an aero tuck position for XC racing.  Adjusting body position, also adjusts the power transfer from many different leg muscles.  Whatever the situation may be... knowing where you are NOW with your current bike's Stack and Reach, is a great starting point, on your journey to where you need to go, to get into an even better Fat Bike geometry.



For Fat Bike FITMENT, primary importance Frame Geometry numbers are

  • Stack

  • Reach

The next most important frame geometry numbers are

  • Chainstay Length

  • Stand Over Height (especially for winter riding)

  • Bottom Bracket Drop

  • Heat Tube Angle

  • Amount of Suspension Correction for different forks

  • Max Tire Width

Please don't underestimate the importance of these stats, as they can significantly affect (or alter) your riding experience.  All Fat Bikes are not created the same.  Some are clearly better designs than others.


For Fat Bikes PURCHASED in 2017, the Most Important FRAME Features to Look for are

  • Frame Clearance for up to 4.8in tires

  • Thru-Axle Hub Spacing of 150mm FR, and 177 or 197 RR

  • For All-Mountain riding (AM), frame suspension corrected up to 120mm

  • For XC racing, frame suspension corrected to 100mm

  • Chainstay length of 435-450mm for AM and XC use, and 455-465mm for general Snow-biking/Adventuring

Frame Geometry Measurements depending on personal taste are

  • Seat Tube Angle (angle/position of rider weight over the BB and rear wheel)

  • Head Tube Angle (how responsive and "twitchy" will the steering be, vs. how "delayed" it may feel)

  • Bottom Bracket Drop (how low, or how tall is the bike's center of gravity)


Trends To Look For in the Fat Bike Industry for 2017

(as compared to previous years 2014-2016)

  • MUCH Shorter Chainstays (if your bike is pushing 465+, its outdated and won't handle singletrack as well - aka a "Moose" or "RSD Mayor" bike)

  • Stricter warranties on carbon full-suspension Fat bikes. If you want the best survivability on AM trails, go ALLOY FSFB, like the FOES MUTZ. (Several overseas carbon full-suspension frames have been cracking, and/or cannot sustain repeated trail crashes, and must be replaced).

  • More Carbon parts (Carbon frame, rims, handlebar, seat post and crankset are now standard on many builds)

  • 1x11 and 1x12 SPD drivetrains have replaced 10spd drivetrains. (10 SPD or lower drivetrains are now outdated and being phased out)

  • Wheelset accommodations for : 26 x 4.8in / 27.5 x 4.0in / 29 x 3.25in tires.

  • Growing interest in strength vs weight savings in carbon wheelsets. example - HED Fat Bike wheelsets are only SNOW RATED, and require a minimum of 8 PSI at all times, to protect from rim strike delamination. Not many are aware of this. Whereas, a seriously engineered carbon wheelset like the Fatback Footprint, is practically AM-rated and can take insane amounts of abuse. The difference in weight can be about 1.25 lbs. But the security factor allows 4-season riding under any reasonable tire PSI.

  • Practically all stock rims (alloy or carbon) are now tubeless compatible. (this provides many benefits, including reduced rolling resistance, decreased overall weight, and increased puncture protection.)

  • Thru-Axle (TA) has replaced Quick-Release (QR). (stay clear of 135mm FR and 170mm RR QR setups as they are now phased out)

  • 150mm FR and 197mm RR hub spacing has become the standard for most Fat Bikes. Some PLUS bikes and FSFBs use 177mm TA RR.

  • BB drop is averaging 50-60mm.

  • 26in rims are now averaging 68-83mm widths. This is down from 80-100mm from previous years.

  • 27.5in rims have been introduced, but haven't taken full hold because they can interfere with some suspension fork setups when using 4.5+in tires. (example : 27.5 wheelset, with 4.5in+ tires are not compatible with Bluto suspension forks because of clearance issues). Note the Mastodon PRO EXT and all WREN ATK series of suspension forks are fully compatible with 27.5" fat bike wheelsets.

  • Very few bikes now ship with 5in tires on 100mm rims. Trend with "weight weenie" manufacturers is to ship 26 x 4.0in tires on 80mm rims to save weight. (these bikes usually require upgrades to wider tires to handle the snow).

  • Alloy Fat Bikes are now 27 lbs or less for the nicer models. 33-36 lbs for the starter models, and above that weight is outdated tech.

  • Carbon Fat Bikes are now commonly shipping at between 24-28 lbs, depending on stock configuration. (tires, wheelsets and fork selections make up most of the weight difference between the models, and to a lesser extent, the groupset and crankset purchased affects overall bike weight the most). We recently custom built a 4-season rated 22.1 lb FATBACK CORVUS FLT. Or, snow-rated only, it weighed in at 20.7 lbs.

  • Carbon Fat Bike frames are now all generally around 2.75 to 3.5 lbs. Some are only XC rated, while some are further strengthened for AM use (like the Fatback Skookum), and may weigh a bit more...like 1500gr versus 1250gr.

  • Medium-Duty Front Suspension : Starter to mid-spec Fat Bikes will ship with either an alloy or carbon rigid fork. Some may ship with the new Mastodon COMP model. (The Bluto is now outdated and not suggested for any build). (The LAUF Carbonara is an event specific fork and not recommended for all-round everyday use).

  • Heavy-Duty Front Suspension : Higher-end models are shipping with either a WREN 110 ATK or Manitou Mastodon PRO fully adjustable suspension fork, in replacement of a rigid carbon fork.

  • AM hardtail suspension corrected frames are designed to handle 120mm suspension forks. (Wren ATK 110, Wren ATK 120, Mastodon PRO 120 STD / EXT)

  • XC hardtail suspension corrected frames are designed to handle up to 100mm suspension forks. (very beginner old-stock 2015-16 models = BLUTO RL or RCT3 100. Advanced 2017 builds include Mastodon PRO 100 STD / EXT and Wren 110 ATK series..that can be configured for 100mm travel and AC "axle to crown" height ).

  • AM Full-Suspension frames (like the FOES MUTZ 150), is suspension corrected Front and Rear to 150mm (6in) of travel !! This bike requires a special fork, designed just for it, like the Mastodon PRO 150 EXT and the WREN ATK 150.

  • Adventure/snow-bikes do not always have suspension corrected frames, and will ship standard with a nice carbon rigid fork, sometimes with an option for a LAUF Carbonara. (0-15mm of constant operating range (COR) of travel) - NOTE: Lauf Carbonara's do not allow a full 60mm of constant suspension travel, as their name/description may imply). (you can read about that << here >>)


STACK and REACH Definition

  "The evolution of mountain bikes has made the old system of top tube and seat tube based sizing irrelevant. The wide range in seat tube angles and bottom bracket heights can create a situation where one bike could feel longer or taller than another frame with the same measurements. Once a rider is in a standing position, the fit and feel of their bike’s cockpit is determined exclusively by the handlebar and pedals. Finding the specific geometric relationship between those two points is the only way to accurately compare the fit and feel of different bicycle frames."

"The horizontal distance from the bottom bracket center to the top of the headtube centerline is referred to as REACH. The vertical distance between these two points is known as STACK. By comparing the reach and stack on different frame models, the rider is able to identify exactly how their bike will fit and feel on the trail. This system eliminates any uncertainty created by the seat tube angle, and forever drops the need for “actual” and “effective” top tube measurements. The reach and stack of a frame is the most important sizing information for a freeride or downhill rider but it is extremely valuable for trail riders, (Fat Bikers) and XC racers as well."  (quote taken from Dec 18. 2008 article in Pinkbike).  


1.  Numb Fingers

2.  Lower Back pain

3.  Knee pain

4.  Saddle soreness

5.  Overall lack of comfort, including shoulder or neck pain that accumulates over time

6.  Foot or Toe pain on long rides, or while sprinting or climbing

7.  Lack of Power Transfer




The charts below contain the STACK and REACH data for HARDTAIL (suspension corrected) Fat bikes available in North America, who openly publish their frame geometry "Stack and Reach" stats.  


  • focusing on Fat Bikes for the North American market, and drawing upon the 60+ different fat bikes we have test ridden to date.

  • removing brands that have gone out of business

  • removing fat bikes that had repeatedly bad reviews from multiple test rides, usually due to poor stock frame geometry or parts configuration.

  • only suspension corrected frames will be listed, that can accommodate the latest suspension forks from Wren and Manitou. (Older Bluto-only compatible designs will be removed, as they are outdated).

  • focusing on fat bikes in the $2000+ USD price point.

  • removing all the individual “badge engineering” company brands, and instead, lump them into the few Chinese OEM frames from which they all license branding rights from.

  • removing all brands that have not updated their fat bike frame designs within the last 3 years, or those that appear to have left the market.

  • removing all frames that use hub standards other than 150/197 TA or 150/177 TA.

  • removing all PLUS+ bikes that are trying to pass themselves off as true Fat bikes. We will note them under a new FAQ Section on “narrow Q” PLUS/FAT bikes. We believe they have created their own market segment, and it does not entirely cross over into full fat bike compatibility.

  • updating the full suspension fat bike Stack and Reach charts and removing all the Chinese OEM brands, especially those Chinese OEM carbon frame brands that had all the reported frame cracks.

  • If you are in the used fat bike market, (circa 2014-17) you may want to download copies of these charts, before they are removed from the website. Our internal database will retain all frame geometry information, but we will only be publishing current model year Stack and Reach data moving forward, for the major players in the market.








  • The STACK of the Fat Bike frames increase as you move vertically from bottom to top of the chart.

    • A taller "STACK" basically translates to a more upright riding position (the top of the headset is farther from the ground).

    • Riders with longer legs, will definitely want a taller STACK.

    • A Fat bike with a tall STACK and short to medium Reach, will put the rider in an upright riding position and more closely resemble all-mountain MTB geometry.


  • The "REACH" of the Fat Bike frames increase, as you move horizontally from left to right on the chart.

    • As REACH increases, the rider will stretch out more over the frame, in order to reach and hold the handlebars.

    • A longer REACH usually is indicative of a longer torso and arms of the rider, and usually translates to taller riders using longer "REACH" on their Fat Bikes.

    • A longer reach does not always translate directly into a more comfortable Fat bike... it can easily turn into the opposite. Proper body-fitment sizing is critical.

    • XC racers, or winter endurance riders sometimes prefer more "reach"... but it may come at the expense of agility and maneuverability.


  • The longer the chainstay, generally the better the steep climbing ability of the frame.

  • A longer chainstay can also assist with higher sprint speeds on hardpack, as the rear wheel will track a bit differently, and help keep the bike pointed ahead.

  • The shorter the chainstay, the more agile the frame will be in singletrack conditions, and closer resemble MTB geometry.


Break it down into several key FUNCTIONAL areas

  • Frame Stack

  • Frame Reach

  • Chainstay length

  • Personal body fitment measurements

  • Rider race position vs Rider all-day comfort

  • Intended use of the bike (AM, XC, race, adventuring, snow-biking, etc)

  • Frame material - Carbon vs Alloy

Optional Considerations

  • Q Factor

  • Max tire size

  • Singletrack (AM) vs Doubletrack (XC) handling

  • 3 season vs 4 season (winter) use

  • Rear rack and Pannier bag options

  • Front Suspension options

  • Frame Rear Suspension travel (for FSFB bikes)

  • Thru-Axle Hub compatibility

  • 1x 12spd vs all other drivetrain options

  • GripShift vs Trigger shifting

  • Hydraulic brakes

  • Dropper post routing option

Two Types of Rider Positions

  • (AM) - All-Mountain / Single-track

    • more upright, comfortable position - center of mass towards back of bike

      • best frame type for riders with chronic lower back, shoulder or neck pain

      • great at sprinting, if you move forward on the saddle

      • AM-suspension frames usually corrected for 100-150mm of travel

      • frames usually accept largest wheel size combinations (26, 27.5, 29) due to seat stay, chainstay, and bottom bracket drop configuration

      • best frame type for negotiating tight, twisting courses, or requiring maximum maneuverability

  • (XC) - Adventure / Double-track / Snow-biking

    • rider is more stretched out, in a lower riding position - center of mass towards front of bike

      • frame design usually enhances extended, steep climbing ability, due to longer chainstays and lower front end stack height

      • frames usually optimize sprinting on rolling double-track terrain

      • effective design for winter riding and endurance trekking

      • frames usually suspension corrected for up to 60-100mm of travel

      • frames usually accept largest tire width combinations (4.5”-5.0”), due to seat stay, chainstay, and BB “Q” factor designs

      • look for frames with lowest stand-over height, when considering a fat bike just for the winter months (*very important*)

      • this frame style is not advised for riders with chronic lower back, shoulder or neck pain

      • tallest riders (over 6ft) may find these frames to accommodate your body geometry best

Observing the Results of the FAT BIKE STACK and REACH Charts


These charts were created to fully disclose an unbiased look at all the Fat Bike frames currently offered in North America.  We know everyone arrives here already biased from previous marketing ties, or experiences with their previous road or mtb bike Brands.  That's fine.  We'd ask that you look at this data with an open mind and really consider the possibilities before you make your next purchase in the sport of Fat Biking.  


The 2017 Model Launch has seen some significant changes happening in the industry.  1)  Many companies with unpopular designs from last year dropped out of the market, like Scott.  2) Even more companies got their engineers together and completely redesigned their frames.

Fat Bike companies wanting to stay on the cutting edge of change have re-positioned their "Adventure/Snow" bikes in either the "AM" (All-mountain) or "XC" (cross-country) categories.  Trends in these two regions show shorter chainstays overall.  Smaller Q factors (Like OTSO).  Taller stack and shorter reach for "AM" designs (Fatback Skookum carbon and RM Blizzard alloy), and shorter stack and longer reach for "XC" designs.

One company that always seems to stay ahead of the trending curves and tech changes is Fatback, and they have 3 well-placed models across the geometry sizing spectrum.  The Skookum/FLT in "AM", the Corvus/FLT in "Adventure/Snow" and the Rhino/FLT in "XC".  All have been fine-tuned with the latest frame geometry updates and can still spec 4.8in tires, using 100mm, or many 27.5+ and 29+ wheelset combinations.  They are well placed across the sizing charts and all between 25-30 lbs).  This company is passionate about fat bikes and been designing and building JUST fat bikes for about 10 years now.

For instance, the Iditarod Fat Bike Race Across Alaska, has seen Fatback win over a dozen times, in the harshest climates.  They even beat the sled dog teams and broke world records !!  (click here for more info)



  • Most companies have predictable linear geometry throughout the sizing spectrum... they increase in stack and reach in linear fashion as you progress in size (aka - the bubbles from each size S-M-LG-XL can be connected by an imaginary straight, or slightly rounded line)

    • " name. Both frames are within a few millimeters of each other in overall design. Visually, there are several changes to the tube design, and there is a claimed weight reduction. The Crestone is claimed to be a bit lighter and has a lower stand-over height, which are the two main differences over the 2015 Echo version.

    • There are about 6 small boutique brands that relabel the FM190 mold geometry as their own brand. They also advanced it into the newer OEM CS197 frame. They all have the same geometry, but some may have different tube shapes. Bottom line, it's the same bike, from the same factory in China. Same durability issues long-term. Several copied the original design process that LaMere used in creating their lightweight carbon hard tail a few years ago. These Chinese OEM agents then copied the LaMere Stack and Reach settings and changed the tube shape and frame name. This results again, in the CS-197/Growler/Llevant hardtail frames. (Catalog frames from China - that stole tech originally from another American company's prototype designs, and then later rebadged with other North American "brand" names) to be sold state-side.

    • Only one company had a Fat bike designed with a chainstay that increased in length, as the frame increased in size. That was the Norco Ithaqua carbon. (even though increase was small, 440mm SM, 443mm MD, 445mm LG, 448mm XL. That's an interesting idea.

  • One name brand has two different Fat bike models with almost identical frame geometry. This is is the case for the Borealis Echo and Borealis Crestone. (And these seem to be based off the classic "FM190" frame from China, but with an extended ETT). The Echo was released after the FM190. It appears after reviewing the data, that the Echo frame had several modifications made to it during the revision process. Instead of calling it the "Echo v2", these revisions turned into a new frame, and re-marketed under the "Crestone" name. Both frames are within a few millimeters of each other in overall design. Visually, there are several changes to the tube design, and there is a claimed weight reduction. The Crestone is claimed to be a bit lighter and has a lower stand-over height, which are the two main differences over the 2015 Echo version.

  • There are about 6 small boutique brands that relabel the FM190 mold geometry as their own brand. They also advanced it into the newer OEM CS197 frame. They all have the same geometry, but some may have different tube shapes. Bottom line, it's the same bike, from the same factory in China. Same durability issues long-term. Several copied the original design process that LaMere used in creating their lightweight carbon hard tail a few years ago. These Chinese OEM agents then copied the LaMere Stack and Reach settings and changed the tube shape and frame name. This results again, in the CS-197/Growler/Llevant hardtail frames. (Catalog frames from China - that stole tech originally from another American company's prototype designs, and then later rebadged with other North American "brand" names) to be sold state-side.

  • Only one company had a Fat bike designed with a chainstay that increased in length, as the frame increased in size. That was the Norco Ithaqua carbon. (even though increase was small, 440mm SM, 443mm MD, 445mm LG, 448mm XL. That's an interesting idea.

  • Some Fat Bike models border on MTB "PLUS" bike sizing, and rear tire size is limited. As is the case for the Rocky Mountain Suzi - Q, which is limited to 3.8in tires. If you are looking for a narrow "Q" factor, and short chainstay lengths (434mm) like the Suzi-Q, but want more options on rear tire width, look to the OTSO Voytek instead. The OTSO Voytek beats out the Salsa Beargrease and RM Suzi-Q in almost every category for these fat bikes that closely border the "plus" bike region. The Voytek has an adjustable minimum 430mm rear chainstay length, an even narrower Q-factor than a Suzi-Q, and can take up to 4.6in tires on 26 x 70mm rims. The Stack and Reach geometry on both bikes is very similar.


Note:  6 frames have adjustable chainstay length settings.  

  • OTSO VOYTEK 430-450mm. Accommodates 27.5+ and 29er+ tires sizes and up to 26 x 4.6in tires on 70mm rims.

  • CANYON DUDE 439 to 455mm. Accommodates 27.5 x 3in and 29+ tires. Accepts up to 26 x 4.8in tires on 80mm rims.

  • TREK FARLEY 440 to 455mm. Accommodates 27.5 x 3.0in, 29er x 2.4in, and 26 x 4in tires at 440mm chainstay. Accommodates 27.5 x 4in, 29 x3.0in or 26 x 5.0in tires on 455 chainstay setting (according to TREK)

  • PIVOT LES FAT 437mm to 447mm. Accommodates 26 x 3.8in, 27.5 x 2.8in, 29 x 2.4in tires at 437mm chainstay. Accommodates 26 x 4.8in and 29er x 3.0in tires at 447mm chainstay (according to PIVOT).

  • SALSA MUKLUK 432mm to 449mm. Accommodates 26 x 4.8in, 27.5 x 3.25in and 29 x 3.0in tires.

  • VENTANA EL GORDO 438-465mm. Accommodates 26 x 4.8in tires on 100mm rims, 27.5+ and 29+ tires.


  • frame weight increase by 0.75 to 1.25 lbs

  • some bikes will have tire and rim size limitations

    • if so, this can affect traction, handling, and where the bike can be ridden in terrain extremes

  • chain length changes by up to 40mm or more (4+ links)

  • chainring gearing may need to be adjusted by 2T+ to make up for chain link change, if the chain itself is not replaced when C/S length is modified from one extreme to the other

  • on some models, the geometry will go slack or steep, when C/S is changed

Let’s take the OTSO VOYTEK as an example.

OTSO gave us two of their flagship bikes to test at Bootleg Canyon in Nevada. One was configured in PLUS mode with 27.5 x 2.8 McFly tires, and the other was in FAT mode with 26 x 4.0 Schwalbe Jumbo Jims. So we got to try both versions, at the same time, on the same trails.

It’s a great PLUS bike. But a marginal FAT bike. Here is why :


OTSO tire clearance


  • As chainstay length decreases on these bikes, (pre-cut) chain length increases, which causes slack in the drivetrain, or, chain replacement. Every 20mm of chainstay length change, means roughly 4 chain links (40mm total, 20mm top+20mm bottom)


  • Every 20mm of chainstay length change, translates to a chainring change of about 2T to accommodate the adjustment in chainstay length. So you either need to change chainring size by 2 teeth, or change the chain, or induce slack into the drivetrain, which can cause shifting issues, and chain slap on the chainstay itself.


Let’s say you want to use 26 x 4.6” tires on an OTSO VOYTEK. You can only do this, if using a 65-70mm rim, and force the chainstay to the 450mm position, to gain enough tire and mud clearance for normal riding. You also need to reduce tire pressure to 10 PSI or less.

Note : When running such narrow rims (60-70mm), the true width of the FAT bike tires is noticeably reduced, as the manufacturers rate them based on (MAX) 20-30PSI on 100mm rims. So, bascially a 26 x 4.6” tire on 65mm rims (and 10 PSI or less), may in fact be the same width as a 26 x 3.8” tire on 80mm rims. Bare minimum FAT bike widths.

Let’s say you wanted to use 26 x 4.0” tires on the OTSO VOYTEK, and call it a minimal FAT bike configuration. Yes, it’s possible with rim widths up to 95mm and the chainstay length set at the minimal length of 430mm.

Let’s say you wanted to put on a pair of 26 x 4.8 or 5.0” studded winter tires on 80mm rims, or, use 27.5 x 4.5” winter tires for extra float. Well, it’s not possible. At this point, the VOYTEK is really a PLUS bike frame, with a widened “Q”, and limited FAT tire width capability.

The VOYTEK was initially marketed as a PLUS bike that could handle some FAT bike tire sizes, in limited configuration combinations of the rear chainstay length, tire and rim sizes. The second feature was that this bike had a slightly narrower “Q” factor than “regular” fat bikes (83 vs 100). As a compromise to the narrower “Q”, this bike could only accommodate a true FAT tire, if the rear chainstay was increased in length. When you look at it from all angles, it really does not make too much sense, unless, you want to have full PLUS bike capability, with a wider “Q”, and also have limited FAT bike potential, with a narrower “Q”.

Take a direct competitor to the OTSO VOYTEK. The FATBACK RHINO FLT.

The RHINO FLT can take 26, 27.5, and 29” wheelsets, in all the major FAT bike configurations, with zero limitations or frame configuration changes needed. The RHINO FLT has a chainstay length of 440mm. It can handle 26 x 5” tires on up to 100mm rims at this C/S length. The “Q” factor is as narrow as any other true fat bike. Only difference is rear hub is 197 vs 177 on the VOYTEK. Taller riders can’t even feel the difference in “Q”, especially if you use narrow cranksets, like the RaceFace NEXTR or SRAM/Truvative STYLO carbon cranks, using the “170” or “FAT4” spindle options.

The RHINO FLT can handle the same suspension forks, has a strong lightweight alloy race frame, has rear rack mounts, and is All-Mountain rated. The body position on the frame is similar, with and bit more laid back Stack and Reach.

Are you willing to make all those potential compromises on an OTSO VOYTEK, for a “Q” factor change less than the width of your thumb? I guess that depends on the rider, their height/weight, amount of sand/snow/ice they will be riding in, terrain, and duration of winter conditions.

On the flip-side, you can take a look at a FAT bike like the SALSA MUKLUK. It has an adjustable chainstay between 432mm and 449mm. It can take the same tire sizes as the RHINO FLT, and same “Q” factor, with a 100mm Externally threaded bottom bracket. The MUKLUK starts at a similar C/S length as the RHINO FLT, and lengthens to something just shy of the FATBACK CORVUS FLT. So the MUKLUK is a true fat bike, that plays with C/S geometry in a different way than OTSO.

A stock (alloy) Salsa MUKLUK alloy will weigh in about 1.2-2.0 lbs more than a stock Fatback RHINO FLT, and the (carbon) Salsa MUKLUK will weigh in about the same as a stock (alloy) FATBACK RHINO FLT, based upon similar build-level componentry and frame configurations offered in each manufacturer’s complete build packages.


The OTSO VOYTEK is more of a 3-season PLUS bike entering into the edges of the FAT bike field, whereas the FATBACK RHINO FLT and the SALSA MUKLUK are dedicated 4-season fat bikes, pushing the boundaries of maximum tire and rim size, while maintaining the minimum FAT “Q” crankset width. All three of these bikes have raced in the winter Iditarod, and the true fat bikes end up repeatedly with better results.

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