SKU: 94313673292
e mountainbike fatbike

e mountainbike fatbike ELECTRIC FAT TIRE E-BIKE

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Ships within 48 hours · Estimated delivery Nov 16 - Nov 21

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Description

e mountainbike fatbike ELECTRIC FAT TIRE E-BIKEIntroducing the all new Keystone Electric Fat Tire Bike. Since 2013, Borealis has specialized in lightweight, high end fat bikes. The Keystone is our first ever Class I electric bike. The frame geometry is optimized for riding just about anything with clearance for up to 5 wide tires. Paired with the most technically advanced components in the industry, the Keystone sets the standard for premium quality Electric fat bikes. HIGHLIGHTS Color: Gunmetal

  Introducing the all-new Keystone Electric Fat Tire Bike. Since 2013, Borealis has specialized in lightweight, high end fat bikes. The Keystone is our first ever Class I electric bike. The frame geometry is optimized for riding just about anything with clearance for up to 5” wide tires. Paired with the most technically advanced components in the industry, the Keystone sets the standard for premium quality Electric fat bikes. 

HIGHLIGHTS

  • Color: Gunmetal Grey with Cobalt Blue Graphics
  • Weight: 56 lbs. as shown.
  • Standard features include Shimano EP8 Drive Unit, Shimano 630Wh Battery, SRAM G2 RS brakes, Mastodon Pro EXT 120mm suspension fork, carbon handlebars, dropper seat post, durable Sun Ringle Mulefüt rims and your choice of tires.
  • Frame geometry provides responsive handling, offering maximum control for varying conditions in snow or sand.
  • Tire clearance up to 26x5” and 27.5x4.5”.
  • Lightweight, 6000 series aluminum frame comes with internally routed cables, 1-2 bottle cage mounts and lizard skin protection.
  • Keystone Frames are backed by our LIMITED LIFETIME WARRANTY.

ASSEMBLY

Some assembly required upon receipt. Your bike will be completely assembled and tuned by Borealis, then partially disassembled for shipment. The remaining assembly will require installation of the rear derailleur, chain, fork, seat post, wheels, and handlebars. A kit will be included with your order that has all the necessary tools assemble your bike, including a multi-tool, torque wrench, and shock pump. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. 

Stay tuned for our step-by-step assembly video. 

WHEELS AND TIRES

  • All bikes come standard with tubes.
  • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
  • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

SIZE CHART

BUILD SPECS

Frame Borealis Keystone Aluminum 15", 17", 19", 21"
Drive Unit Shimano DU-EP800
Battery Shimano BT-E8036 (630Wh)
Display Shimano SC-EM800
Assist Switch Shimano SW-EM800L
Speed Sensor Shimano EWSS300L540A
Fork Manitou Mastodon PRO EXT 120mm, 51mm offset
Headset FSA w/ Star Nut
Stem Borealis 50mm
Handlebar Borealis Carbon 
Grips Ergon GP1
Saddle WTB Volt Medium Steel
Seat Collar Borealis Bolt-On
Seatpost KS Lev Integra 125mm (SM, MD) / 150mm (LG, XL)
Brakes SRAM G2 RS
Rotors SRAM HS2 200mm front / 180mm rear
Shifter SRAM AXS Pod Contoller Right Bridge w/ MMX Clamp for GX Eagle Transmission
Derailleur SRAM GX Eagle Transmission Derailleur
Cassette SRAM GX Eagle Transmission Cassette 10-52T
Chain SRAM GX Eagle Transmission Flattop Chain
Crank Arms Samox 170mm
Chainring Mount Samox 104 BCD for 75mm chainline 
Chainring SRAM Eagle Transmission E-Bike MTB Chainring 104 BCD 36T Steel 
Rims Your choice of SunRingle Mulefüt SL - 26x80, 27.5x80, or 27.5x65
Spokes Straight Gauge 2.0 Black
Hubs Borealis Gen 4 15x150 / 12x197
Tires  Your choice. All tire options are listed online.
Included Shimano ECE80042 Battery Charger, AXS Power Pack, Kickstand, UDH Hanger, Key for battery release, Borealis Rear Thru Axle, Remote Battery Charging Adapter
Weight Size Medium w/ Mulefut 27.5x80 & Terrene Yippee Ki Yay 4.3" Tires: 56 lbs.

FRAME SPECS

Wheel / Tire Size 26 x 3.8–5.0" on up to a 100mm rim / 27.5 x 2.8-4.5 on up to a 82mm rim / 29 x 2.25–3.0
Susp Fork Travel 120mm
Fork Offset 51mm
Headset-Upper IS41
Headset-Lower IS52
Seatpost ø31.6mm
Seat Collar ø34.9mm
Dropper Compatible Internal - 125mm for SM & MD / 150mm for LG & XL
Front Derailleur Type Not Compatible
Bottom Bracket Shimano EP8
Crankset (Max Ring) Chainline 75mm / 1x (38t)
Rear Brake (Rotor) 74mm post (160–180mm)
Rear Spacing 197 x 12mm thru-axle
Rear Axle ø12 x 222L, TP= 1.0, TL = 16
Derailleur Hanger SRAM UDH
Bottle Mount  Small & Medium: 1 (downtube) / Large & XL: 2 (downtube & seatube)
Rear Rack Reccomendation Old Man Mountain Divide Fat 
Rear Rack Mounts, Upper Yes
Axle to Crown 531mm
Steerer Tube Size 28.6mm
Steerer Style Tapered
Crown Seat Diameter 40mm

 

GEOMETRY CHART

Small 15" Medium 17" Large 19" X-Large 21"
Effective Top Tube 630 645 660 665
Seat Tube Center to Top 381 432 482 533
Head Tube Length 160 160 175 190
Head Tube Angle 69° 69° 69° 69°
Seat Tube Angle 73° 73° 73° 73°
Chainstay Length 480 480 480 480
BB Drop 60 60 60 60
Reach 420 435 445 446
Stack 688 688 702 716
Standover Height varies based on wheel and tire size
Wheelbase 1187 1207 1223 1229
Fork Offset 51 51 51 51

 FAQ:

Can I use the Keystone in cold temperatures?  It is okay to use your Keystone in the operating temperature range, suggest by Shimano: -10 - 50°C
How do I remove the battery? Each Keystone will come with a set of keys. Make sure to save your spare key and safe location. Insert the key fully into the lock cylinder on the non drive side of the downtube until it stops.  Rotate the key clockwise until the battery drops from the downtube providing access to the latch release mechanism. Use your index finger to gently depress the spring which will fully release the battery. Use caution to support the battery when removing it so it does not fall to the ground. 
How can I file a warranty claim for the drive unit and other electronic components?  Contact an authorized Shimano STEPS dealer.
Can I change my motor/power settings?  Yes, you can customize your motor settings via the app as well as update the firmware. You'll need to download the Shimano E-tube mobile app.
Can I change the max speed?  No. Depending on where you've purchased your Keystone it will either have a max assist speed of 20mph or 25km/h. This setting cannot be modified by the user or a dealer.
Can I purchase an extra battery? Yes, you can purchase a spare battery kit with a spare downtube cover directly from Borealis. Spare battery kits may not be available in all markets. You can also purchase a spare battery from Shimano, but it will not include a battery cover.
Can I ride the Keystone without the battery? No. This will void your warranty with Shimano and cause damage to the motor system.
Do I need to update the firmware / software?  Firmware can be updated via the Shimano E-tube mobile app.
How do I use walk mode?  Hold the upper button (down assistance level) for 1 second until the display turns blue and displays WALK mode. Press and hold the same button to power the rear wheel. 
How long does it take to charge the Shimano 630Wh Battery?  With the included EC-E8004 charger, the battery can fully charge in 6 hours.
How long will my battery last? The remaining battery capacity is affected by temperature and cycle count. Generally, it decreases approximately 5% a year. This means roughly 95% capacity remains after 1 year, and 90% after 2 years.
How should I store my bike and or battery?  Charge your battery to approximately 70% before storing for long periods of time. Store in a cool, indoor location with a stable temperature between approximately 10 - 20 C / 50 - 70 F. No direct exposure to sunlight or rain.
Are the electronic components waterproof?  Yes, the STEPS system is waterproof as long as all components of the system, including the battery and battery cover, are installed correctly. We recommend not using a high-pressure washer to clean your Repeater, but riding in the rain and regular cleaning are okay.
My bike won't turn on, what do I do?  First, make sure all cables are plugged in, if they are then try removing and reinstalling the battery. If it still won't turn on try charging your bike for a few hours. If your bike is too hot or too cold, it might not turn on. If your bike still does not turn on, contact a Transition or Shimano dealer for support.
Should I only charge my battery when it's completely drained?  No, simply charge the battery any time you need it, frequent charges actually help battery longevity. Avoid letting the battery discharge completely. Charge to 70% before storing for long periods.
What are the different error codes and what do they mean?  Whenever you encounter an error code, first cycle the power off and then back on. If the code persists, remove the battery and then reinstall, which will hard reset the system. If neither of these steps resolves the issue, please reference the Shimano error code list. If you cannot resolve your error code via your Etube mobile app please visit your nearest Shimano STEPS dealer or contact Shimano STEPS customer support.
What is the range and how can I maximize it?  There are many factors that affect battery range, such as, how much effort the rider is providing, the gradient of terrain, ambient temperature, and rider weight. The best way to maximize your range it to spend more time in Eco and Trail modes, and minimize the amount of time spent in Boost mode.
What is the widest tire the Keystone can fit?  26x5.0" or 27.5x4.5"
What kind of maintenance is needed on the drive unit and how often?  The drive unit is sealed and cannot be serviced. If there are any issues with the drive unit, it will need to be removed and sent back to Shimano for service or replacement. The drive unit along with the battery is designed to last over 1000 charge cycles. Assuming you're getting 30 miles (48Km) per charge, the drive unit should last 30,000 miles, or much longer than pretty much any other part on your bike.
Why does my bike stop giving assistance over a certain speed?  Depending on where you've purchased your Keystone it will either have a max assist speed of 20mph or 25km/h. This setting cannot be modified by the user or a dealer.
Will environmental temperature affect battery life?  The battery life will be shorter during cold temperatures, this is not a sign of a problem.
Will my bike be delivered with a charged battery?  Your Keystone was shipped in a "sleep" mode with the battery at approximately 30% charge. It is recommended to fully charge your battery before the first ride.


 


Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 94313673292

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4.7 ★★★★★
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Ronda S
Natrona Heights, US
★★★★★ 5
Chuck It Balls!! Best Loved Fetch ball by my Dog!!
Size: Large (Pack of 1), Color: Multi, Size: Large (Pack of 1), Color: Multi
Chuck It large Whistle balls, Absolutely love these great rubber balls, I think there is at least 20-25 balls all over my house, yard and in my boys toy box. At least one is trapped until fall on our ravine hill side, they do bounce high and off his snout for more travel time.!! (Over the fence and into ravine) I subscribe and save getting usually 1 or 2 a month, Really… makes it easy to find one, when they are everywhere!!😜 They are usually blue in color, once in awhile I get an orange one (which I prefer, easier to find in the grass/bushes) These do have a light whistle sound when throwing and my dog will change direction hearing where they are headed. These balls are very durable and last a very very long time. Actually I don’t think one has worn out.. lost yes…. Definitely get the large size, perfect for a med to large dog to play fetch forever!!
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Reviewed in the United States on August 15, 2025
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coach
Waukegan, US
★★★★★ 5
Love this ball!
Size: Large (Pack of 1), Color: Multi
My doberman and her dog friends love this large high bounce rubber fetch ball! She loves to chew it endlessly between throws and her Rottweiler buddy loves to do the same because it has a hole through it. I definitely recommend the large 3 inch ball for larger dogs.
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Reviewed in the United States on November 15, 2025
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Michael Murrell
Birmingham, US
★★★★★ 4
The orange ones are perfect!
Size: Medium (Pack of 2), Color: Assorted
I wish I could give 4 1/2 stars but it isn't possible. The reason why I don't give 5 stars is because no one sells these in a 2 pack of just orange balls. I was able to find blue only but not orange only. I have a pitbull and so does my good friend. We take our dogs out all the time and they absolutely love chasing these balls.... The orange ones to be exact. They will not play with or bring the blue balls back. They are a waste. I had to buy 2 packs to keep the oranges. I'm taking the blue ones to the local dog park and just dropping them off. Now to the reason these balls deserve 5 stars: They are super easy to throw and they also make a slight whistling noise when you throw them because of the holes. They are real easy to wash due to the material. Also, they are pretty indestructible. The only reason I'm ordering more is due to them being lost. Our dogs have never torn them apart. I'm sure they could if we let them, but we use these for chase, not as chew toys. My friend also tied a rope through one of the balls to throw and retrieve with the rope. He uses this as a fun indoor toy. These do not float in water but I buy other chuckit balls for that purpose. They have the orange balls with the blue stripe which work great in pools. The balls are awesome and I keep coming back for more. Hopefully your dogs like the blue balls.
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Reviewed in the United States on December 8, 2015
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Auskan
Natrona Heights, US
★★★★★ 5
Worth the money
Size: Medium (Pack of 2), Color: Assorted
I've had several sizes of Chuck-It ball launchers for years but had resisted buying the balls to go with them because I had about 50 tennis balls already that cost only pennies apiece and these were quite a bit more expensive. But, I got tired of the dogs chewing up the tennis balls. I'd start a ball throwing session with a brand new ball and for the first few throws it would sail through the air and the dogs would have to work to retrieve it. However on the way back, their jaws would work it, chomp-chomp-chomp. And when they returned to me, they'd want to stand there and chomp some more, despite my command to "Drop it!" Within 30 minutes, the brand new ball would have a hole in it and then instead of sailing several football fields through the air, then bouncing over a couple of trees, I'd throw it and it would piddle unenthusiastically to the end of the driveway before falling to the ground with a sulky thud, not even bothering to bounce. So - I finally grew tired of going through a ball every time I play with the dogs - which is everyday - and ordered these chuck-it balls. They are the same size as a tennis ball but made of a rubber-like material (not silicone) and after several months of use, have no wear and tear on them at all. The dogs can exercise their gums on them all the way back to me - throw after throw - and the ball still flies the same distance each time, and bounces satisfyingly upon contact with the ground. The description says "colors may vary" but the first packet I ordered were blue and orange as pictured. Unfortunately my dog lost the orange one the first time we used it. She got thirsty and ran down to our pond for a drink, dropped the ball in the pond and it hasn't been seen since. It is dense enough it doesn't float as a tennis ball might, and by now is probably so covered in mud and slime that I wouldn't recognize it if I tripped over it. Lesson learned: we don't throw the ball in the pond pasture any more. After losing the orange ball, I ordered a second packet of the balls so that I would always have a spare. The second packet is also blue and orange. So while colors may vary, in my experience so far, they haven't (which doesn't matter to me or the dogs).
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Reviewed in the United States on March 1, 2015
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Dawn T Conway
West Palm Beach, US
★★★★★ 5
Super Chewer Friendly!!
Size: Large (Pack of 1), Color: Multi
This ball is perfect for the super Chewer!! It is squishy and durable rubber that stands up to the aggressive chewer. It does not squeak. It has great bounce and is a great toy for fetch. Very cute to watching my pup bring the ball back for another throw. The rubber doesn't stick or have an average powering smell. It smells just like a rubber ball. It is highly functional for a great game of fetch! Highly recommend and very happy with our purchase. It is well worth the price. We will be ordering more.
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Reviewed in the United States on May 20, 2025

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