2020 Biktrix Juggernaut Ultra FS Review


Technical Specs & Ratings



Juggernaut Ultra FS


Class 2, Other


Full Suspension



Hydraulic Disc



696 Wh

696 Wh

72.8 lbs / 33.05 kgs



Frame Details

6061 Aluminum Alloy, Hydroformed


Full Suspension


RockShox Deluxe or Monarch Air Suspension, 100 mm or 130 mm Travel, Compression Adjust, Rebound Adjust, 197 mm Hub Spacing, 12 mm Thru Axle with 6 mm Hex Bolt

Biktrix Inverted Air Suspension, 100 mm Travel, Compression Adjust, Rebound Adjust, 35 mm Black or Gold Anodized Stanchions, Magnesium Uppers, 150 mm Hub Spacing, 15 mm Thru-Axle with 5 mm Hex Bolt, Optional DNM USD-6 Inverted Air Fork 110 mm Travel (Lighter), Optional WREN Inverted Air Fork 150 mm Travel (Lighter, Adjustable Travel, Better Performance)

Aluminum Alloy, Double Wall, Punched Out, 80 mm Outer Width, 36 Hole | Spokes: Stainless Steel, 13 Gauge, Black with Brass Nipples

Kenda Juggernaut Pro, 26” x 4.0” (98-559), Optional Kenda Havoc 27.5" x 3.0", Optional Schwalbe Super Moto-X 27.5" x 2.8", Kenda Juggernaut Details: 5 to 30 PSI, 0.4 to 2.1 BAR, Reflective Branding, 120 Threads Per Inch (TPI) Casing, Dual Tread Compound (DTC), Tubeless Race (Tubeless Ready)


Integrated, Sealed Cartridge, Tapered 1-1/8" to 1-1/2" (44 mm to 56 mm Outer Diameter)

Biktric Branded Promax, Aluminum Alloy, 90 mm Length, 6° Rise, Two 10 mm Spacers, One 5 mm Spacer

Biktrix Branded Promax, Aluminum Alloy, 5° Rise, 5° Backsweep, 820 mm Width

Flat, Rubber, Non-Locking, Optional Ergonomic Locking

Biktrix Branded Rigid Aluminium Alloy (Single Bolt Forged Clamp), Optional Suspension Post Upgrade


Velo Plush, Black with Reflective Patch Center Back

Wellgo K79 Platform Aluminum Alloy with Fixed Pins

Hydraulic Disc

Tektro Dorado HD-E500 Hydraulic Disc with 180 mm Rotors, Dual-Piston Calipers, Tektro HD-E500 Three-Finger Adjustable Levers with Motor Inhibitors and Shift Detection, Optional Magura MT5E Quad Piston Brakes with Motor Inhibitors and Shift Detection


More Details


1 Year Comprehensive, Lifetime Frame

United States, Canada


17, 19

17" Seat Tube, 24" Reach, 29.75" Stand Over Height, 33.5" Minimum Saddle Height, 41" Maximum Saddle Height, 32.25" Width, 51.75" Wheelbase, 82" Length

Satin Black with Red and White Accents, Brushed Aluminum with Black Accents

Optional Custom Rear Rack (Clamp-Mounts to Seat Stays)

Tektro Dorado HD-E500 Hydraulic Disc with 180 mm Rotors, Dual-Piston Calipers, Tektro HD-E500 Three-Finger Adjustable Levers with Motor Inhibitors and Shift Detection, Optional Magura MT5E Quad Piston Brakes with Motor Inhibitors and Shift Detection

Video Reviews

Written Reviews

This review was provided for free, but Biktrix did organize delivery of a temporary demo bike and accessories to test. My goal is to be transparent and unbiased with you, this video and writeup are not meant to be an endorsement of Biktrix products. I welcome your corrections, additions, and feedback in the comments below, and the Biktrix forums.


  • Biktrix started way back in 2013, launching their first product through a crowdfunding campaign in 2014. They are unique and remain relevant today because they offer so many choices for each model without raising the price significantly. That can be seen here, with the Juggernaut Ultra FS with the upgrade paths for suspension fork, battery capacity, and brake quality. They also offer three wheel size / tire options ranging from 4″ fat, plus sized knobby for trail riding, and high volume road tires.
  • The Biktrix Juggernaut Ultra FS was overhauled for 2020 / 2021 with an entirely new frame geometry. We reviewed the 2019 version a while back, and I was excited to see this new model because there are very few full suspension fat tire ebikes in existence today. This one has a powerful multi-sensing mid-drive with physical shift detection! That makes it powerful, well balanced, and fairly durable. The biggest downside I saw was that the power of the motor sometimes flexed the rear swing arm, causing the gears to “phantom shift” and cause crunching / mashing. This is especially true for heavier riders or when operating at full power and ascending.


  • It’s amazing to see an ebike with this much power and so many customization options for such a low price. It’s incredible to me that such a niche offering is being produced in two frame sizes and two color schemes as well! The bike isn’t perfect, but it is definitely special in a lot of ways.
  • Great motor choice, given the heavier weight of the bike and possibility of larger tires (like the 26″ x 4″ on my demo model) the Bafang Ultra M620 was a good choice. It delivers an incredible 160nm of torque and the motor controller listens for rear wheel speed, pedal cadence, and pedal torque.
  • I was told that many customers actually use the Juggernaut Ultra FS for commuting, and I can see how this would be fast, powerful, and comfortable on many terrain types… even off road. For those who are riding near traffic, I love that the bike comes with tires that have reflective stripes and puncture protection. I also appreciate the integrated headlight (mounted high up and pointing where you steer) as well as the battery powered rear light with multiple flashing modes. To be clear, I think the fat Kenda Juggernaut Pro tires and Schwalbe Super Moto-X slick tires are reflective, but maybe not the Kenda Havok tires (which are more for cross country / trail riding).
  • Commuters will appreciate the optional rear rack and fenders that Biktrix offers for this model. Having something you know will fit the wider dropout and larger tire sizes is nice. The only downside is that the rear rack and fender mounts to the seat stays and are therefor sprung vs. unsprung weight. Your gear could get bounced around more in this position vs. wearing a backpack or using a seatpost mounted arm style platform rack. The downside of those is that they can get bumped side to side easily and don’t support as much weight.
  • For this review, I was riding the 17″ small-medium frame size in black. Biktrix also produces a 19″ medium-large and both can be had in black or brushed aluminum alloy. Coming back to safety, the brushed alloy will probably offer an improved visual footprint and just be brighter for cars to see, but even the black has some nice white accents.
  • The 11-speed drivetrain is pretty great. It uses a SRAM NX derailleur and offers an 11 to 42 tooth spread for comfortable pedal cadence options when climbing or riding at high speeds. This bike can go up to 35mph when unlocked, after all. The steel chainring uses a narrow-wide tooth patter than really grabs the chain, and also has a thick aluminum alloy guide that doubles as a bash guard for off-road use.
  • One of my favorite parts of this bike is the physical shift detection setup. This significantly reduces wear on the chain, derailleur, and rear sprockets. It’s a must-have for such a powerful motor, but wasn’t completely necessary given the multi-sensor torque sensing motor controller. Biktrix used the part and also added motor inhibitors to both brake levers. Great job here!
  • The motor itself is very powerful, but not super loud. The motor controller measures rear wheel speed, pedal cadence, and pedal torque. Aside from being a fairly heavy and large motor, I love everything about it! It offers 110 RPM pedal support and up to 160 newton meters of torque… which is incredible. Most ebikes I test only offer 80nm or possibly 90nm. Thankfully though, it’s the kind motor and controller setup that lets you go slowly and gently even in the highest assist level if you aren’t applying a lot of pedal pressure, it’s great for more technical riding, or doing wheelies ;)
  • Given the power and weight of this bike, combined with the heavier wheel and tire options (4″ fat tires), I love that they chose an inverted suspension fork with sturdy 15mm thru-axle! Inverted suspension is stiffer than traditional, and the stock suspension fork offers compression adjust, rebound adjust, air pressure settings, and it has lower stanchion protectors with black anodized stanchions. It’s pretty sweet, and not something I’m used to seeing outside of downhill bikes. The stock suspension and first level upgrade offer 100mm of travel, but the highest level WREN upgrade offers 130mm of travel. As cool as it all is, the rake is a bit relaxed for me, and the longer travel WREN could change the frame geometry. I feel like this is a half downhill half cross country hybrid that is a bit awkward at times.
  • If you do choose the tire, suspension, brake, or battery upgrades, Biktrix will install them all for you. This isn’t the kind of ebike where you get it in multiple parts and have to do a lot of work to get going. Just attach the front wheel, turn the handlebar, put on the pedals, and maybe do a once-over inspection to make sure everything else is secure and shifting properly.
  • One more thing about the tires, the fat Kenda Juggernaut Pro tires come tubeless ready (so you can convert to tubeless). This allows them to ride at lower pressure without the risk of pinch flats, and it also reduced the weight of the tires which reduces the overall weigh the bike but also reduces the work that the suspension has to do by lowering unsprung weight.
  • Biktrix designed their own fender, and identified a third party option, that will work on this bike, even with the optional rear rack. Biktrix sells the custom front “Armadillo” fender for $80 and rear “Mudhugger” fender for $40, which can be seen in the video at 9:39.
  • I like that the Reention Dorado battery packs all have a full sized USB Type A charging port on the top right hand side. This could be useful for charging a phone while riding (just don’t snag the cable), or as a power bank if you go bikepacking and need to run a small light in your tent.
  • Having a removable battery and 3.5 or 4 amp fast charger is great, because it lets you protect the battery cells from extreme heat or cold, and spend less time in between rides. Many comparable ebikes come with slower 2 amp chargers, but Biktrix starts with 3.5 amp and then upgrades to 4 amp for free along with their larger battery packs.
  • The stock display is pretty nice, it’s large and produces some haptic buzzing feedback when buttons are pressed. I was told that Biktrix also has an optional replacement called the Bafang 500C for those who prefer a different menu system. I was fine with the stock display, which is shown in the pictures and videos above.
  • I love that Biktrix offers shorter 152mm crank arms for this bike, because it allows people who want to pedal through turns to do so without creating pedal strike. It’s a unique offering that I rarely hear mentioned, and it speaks to the different type of riding and advanced torque sensing drive system on offer here. I was told that compared to the prior 2019 model year frame, the latest version has 1″ increased ground clearance as well.
  • Other upgrades for this new model include new bushings, new suspension geometry, shorter chainstay (for stiffness and quicker turning), slacker head tube angle to increase stability at high speeds (they say it’s more planted)
  • I was told that the company can sell multiple wheelsets with each bike, so you could have your on-road and off-road, your snow ready fat tires and trail ready plus sized tires… that’s kind of neat.
  • Other minor positives include the extra wide and sturdy Wellgo alloy platform pedals, durable and smooth SRAM trigger shifter design (both high and low gear levers use right thumb vs. your index finger which should be on the brake lever), and an overall great weight distribution (low and center for improved stability and handling).


  • The biggest downside to this setup that I and my friends noticed after taking multiple test rides is that the powerful mid-drive motor pulls so hard on the drivetrain, that it flexes the rear swing arm a bit and can cause phantom gear shifting if you’re in the highest gears. This can damage the chain and rear sprockets, you can hear them crunching during parts of my ride test when I climb a very steep hill at 30:47. You can reduce this by accelerating more gradually or using the lowest gear (or gears that are more inline with the chainring). The phantom shifting may be more pronounced for heavy riders, those operating in the highest level of assist, and those climbing steep hills.
  • For me personally, the steer tube angle is too relaxed. It makes steering at low speed feel twitchy and reminds me of a downhill bike, which does not seem like the primary application of this ebike. I would prefer a slightly steeper head tube angle with less relaxed rake… something in between the first model and this newer model. The people at Biktrix told me that it helps improve stability at high speed, which I see as true to an extent… but it also requires the need for oversteer if you opt for the big heavy tires, and made the bike much longer which can take up a lot of space and be difficult to maneuver through doors.
  • Depending on how you plan to transport this ebike, it’s so long that it might not fit in your car rack. I have a Küat Sherpa rack and it did not accommodate this ebike. The wheelbase is 51.75″ and the fat tires add extra thickness and length.
  • In addition to being long, the bike is very heavy compared to most others that I review. This is especially true with the fat tire option. The bike I received had the battery pack upgrade, which adds some weight, and I measured it at 72lbs total. Thankfully, the 9lb or 10.5lb battery pack can be removed to make the bike easier to lift, and I would also recommend transporting it without the battery so as not to stress bike racks.
  • Depending on how this bike is setup, it may be illegal on bike paths and trails where you live. The motor is rated at 1,000+ watts, which surpasses the 750 watt US and 500 watt Canadian Class 1, 2, and 3 restrictions. For this reason, it may be best suited to off-road use or on private property. I had mine shipped to comply with local regulations, and it still felt very powerful. Note that it does not have the proper DOT rating or lights (with turn signals) to be licensed as a moped without modification.
  • The Biktrix Juggernaut Ultra FS base model increased in price by $100 compared to the prior generation. I think the upgrades and inflation make this understandable, but I feel that the new super relaxed head tube angle is a drawback compared to the original design.
  • The stock brakes are the bare minimum for what I would consider safe given the weight and power of this ebike. Thankfully, Biktrix does offer an upgrade to quad piston calipers. I’d love to see a thick 203mm rotor as well, but then it may zing as the rear swing arm flexes under motor power or heavy braking.
  • This is a very minor complaint, more of an awareness point to be shared, but the extra large battery pack upgrade for this bike is not symmetrical. It will bulge out to the left side of the frame which could compromise handling a bit and become prone to kicks and scratches.
  • The battery charging port is very low, positioned near the left crank arm. This makes it vulnerable to snags and bumps by the cranks, and difficult to see and reach when charging. It definitely helps to have a kickstand to balance the bike when plugging in and charging, and that will cost extra! I recommend the kickstand for urban and light cross country use so you don’t have to lean the bike over or risk having it tip as easily. For those taking on all-mountain or downhill conditions, the kickstand could bounce a lot more and crank arms could strike… so consider their shorter 152mm crank arms and then be careful when leaning the bike over and charging… ideally you’d lay the bike on the non-drivetrain side, but again, this is where the charging port is, so maybe just remove the battery pack to charge each time.
  • Other minor complaints include the display not being removable (you can swivel a bit to decrease glare), the lack of a derailleur guard for off-road riding and protection during shipping, and lack of any bottle cage mounts.

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