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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:
- 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
4.1 ★★★★★
Based on 28 reviews
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Product Reviews
★★★★★ 5
Desk organizer
I like the wood and metal look. The pencil cup was easy to put together and it is sturdy. It is great to have some organization on your desk.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 24, 2026
★★★★★ 5
Love this protection plan
Quick and easy. My daughter's cracked her screen on her phone, as soon as it happened I went on the app, filed the claim. Ten minutes later I received the email with the shipping lable. The following day I dropped the phone off at ups and 4 hours later I received the digital gift card. Ive filed several claims since getting the protection plan and with four kids its definitelysomething im glad to have especially since i dont have to buy a protectionplan for each item now. I have filed claims for electric scooter the stoped working for no reason, my son's phone stopped charging, my oldest daughter cracked her phone screen, my son's video game controllers up and died and each time it was quick and easy and no fuss
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 13, 2026
★★★★★ 5
If they can't fix it they will replace it.
This protection plan that i pay monthly for paid for itself ten fold. My 3D printer just quit working and after the manufacturer warrenty had ran out at that. I submitted my claim they emailed me a shipping label in which I shipped out my printer that same day. Two days later they received my printer determined it couldc not be fixed and sent me a Amazon gift card for the full price of my printer. Today I will be receiving my new 3d printer thanks to Complete Protect. I highly recommend anyone and everyone to purchase this policy. This warrenty is like having a home warrenty like Homeshield but for your electronics and probably other stuff that i just have not read to see what else. This insurance will save me so much money over the corse of this year and every year after that. Thank you Complete Protect.
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Reviewed in the United States on May 22, 2026
★★★★★ 1
Don't waste your money - these people will not help you
On March 9th 2024, I purchased a MCombo Lift Chair costing $785. On the same day, through the same Amazon account (my PERSONAL account since I also have a business account), I purchased an Asurion Complete Protect policy at the cost of $16.99 per month plus taxes. About one month ago, a problem arose with the chair that required me to make a claim using the "Complete Protect" policy that I had purchased for that very item. The claim was initiated on January 1st, 2025 - On January 3rd, I received an email asking me for photographs showing the damage for which I was making a claim. I sent those photographs via email to the address provided on January 6th. On January 27th, having not received ANY response from Asurion, I contacted them via phone and was told that my purchase had been made with a business account, that it was being used for business purposes, and was therefore not covered. I assured the Asurion Representative that it was most certainly not a business use, and that the chair that I was claiming for had been purchased because I had extensive shoulder surgery done that made it impossible to get in and out of bed. After speaking (unsuccessfully) with the Asurion Rep, I then contacted Amazon Customer Service. I spoke with an Amazon Customer Service Representative on the phone who confirmed that I had in fact used my personal account to purchase the chair and the Asurion Complete Protect policy. That representative went on to send a message to Asurion on my behalf confirming that the purchase was for personal use and not business use. Asurion responded, asking me to call them with the order number for the Asurion purchase. The number I gave was the exact same order number on my order history, however, the Asurion Rep could not find it. I was finally able to discover that the order number in Asurion's system was entirely different and isn't even in the same format as an Amazon order number.
Upon the Asurion representative finding my plan, she informed me that the chair was listed as being purchased for business use (despite Amazon confirming that it was NOT) but that I should give them "a couple of business days" to resolve the issue. Five business days later, still no response and so I called them again (Yesterday - February 1st 2025)... Lo and behold, I got the same crap yet again... the purchase was listed as business use and was therefore being denied, but she promised to remove the business use commentary and put the claim through again.
Today, February 2nd, I called Amazon yet again to escalate and had to call THREE times because the first two calls resulted in me finally being connected to an Asurion representative (two different reps) and each time, the Asurion representative hung up the phone as soon as my name was mentioned.
It has become clear to me that the Asurion "Complete Protect" policy is a SCAM - they will NOT take care of your issue, regardless of how long you've been paying. I have been paying every month since March 9th last year - so they've received over $170 from me thus far, with zero other claims, and if I am able to cancel right now, I will only receive $16.99 back. All I want, is the chair that I purchased the policy for coverage of, to be repaired or replaced. Asurion are NOT helping, and are actively avoiding contact.
At this point, I am considering legal action against Asurion for fraud - perhaps even a Class Action. I'll wait and see if my issue gets resolved within the next 10 days or so.
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Reviewed in the United States on February 2, 2025
★★★★★ 5
Simple and hassle free claims process
I have had to use my insurance policy for several items and the process was simple and hassle free. I mainly purchased this policy / subscription because of one very expensive item I bought with a likelihood off electronic or mechanical malfunction at some point and wanted it covered but I have used it for several other lower priced items that had failed on me. This type of policy would be great for household who purchases a lot of electronics which really isn't me.
But The process almost couldn't be easier.
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Reviewed in the United States on June 1, 2026
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