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Description
fatbike e bike fully 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
4.3 ★★★★★
Based on 27 reviews
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Product Reviews
★★★★★ 4
Great read
Format: Kindle
It’s honestly rare to find a book that manages to be both a gripping thriller AND an emotional, hopeful story at the same time, but this one somehow pulled it off.
The story follows Cami, whose entire life is shattered after a brutal home invasion leaves her traumatized and her mother and younger sister dead. Right before everything happened, she had just found out she was pregnant and was preparing to start her future, so watching everything get ripped away from her was absolutely heartbreaking.
Years later, Cami has rebuilt a quiet life for herself and is finally finding some sense of peace… until she receives a phone call telling her there’s a little boy being held captive somewhere in a cabin in the woods.
And that’s when everything starts unraveling again.
The search for the missing child reconnects her with Rex, a former classmate who became an outcast in the aftermath of the original tragedy. After being unfairly viewed as suspicious by the community despite being cleared, Rex lost the scholarship that was supposed to change his future and eventually enlisted in the military. Now he’s this highly skilled tech expert carrying around his own trauma and pain, and honestly I really liked his character.
What I appreciated most about this book was how layered it felt. Underneath the mystery and suspense, it’s really a story about survival, trauma, resilience, and how people try to rebuild themselves after unimaginable loss. Mia did a really good job balancing the darker subject matter with moments of hope and healing without making either side feel too overwhelming.
The opening of this book is INTENSE and immediately hooks you. There were definitely moments where my interest dipped a little in the middle because the pacing shifted and the story started unfolding in a different direction than I expected, so I had to kind of regroup and settle into what the story was trying to do. Some of the execution did not fully work for me all the time, especially with certain reveals being held back for later impact, but overall I was still really invested in uncovering the truth.
I also really liked that even some of the characters I disliked ended up getting endings that felt satisfying in their own way.
The mystery kept me engaged, the emotional elements hit hard, and the characters felt layered and human. It’s dark, tragic, hopeful, suspenseful, and ultimately a story about surviving things that should have destroyed you.
Just definitely check trigger warnings beforehand because this book does contain violence against women and some heavy subject matter.
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Reviewed in the United States on May 16, 2026
★★★★★ 5
Excellent read
Format: Kindle
One of the best books I've ever read, full of surprises. Only complaint is the f bombs, totally unnecessary, adds nothing.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 30, 2026
★★★★★ 3
Mixed feelings about this book
Format: Kindle
I do not recommend this to anyone suffering from trauma. There are some very triggering things in this book and it isn’t a justifiable risk for anyone who has PTSD.
However, if your life has been relatively “normal” and fairly mundane, then you might enjoy reading this book as an escape into a series of exciting events that put the characters through major suffering.
If books got ratings the way movies and TV shows do, I would rate it MA (mature audience) or R (restricted audience) for language, violence, sex, and thematic content. Reader discretion advised.
Pros- fast pace, twisty plot, mysteries, surprises, lots of action, hard to put down
Cons- often unrealistic portrayal of how real people would actually act in the various situations in the book, and sometimes the situations themselves felt a bit of a stretch
This was a plot-driven book with one-dimensional characters- “bad guys” predictably did and said horrible things, “good guys” reliably said and did “good” things. Nobody really surprised the reader, even when they did unexpected things, because it was more a matter of getting the full picture and then realizing that their actions were fully consistent with their place in the “good guy” or “bad guy” category.
Sometimes I found myself wondering if the author had any understanding of how trauma affects people. Those I know who suffer from PTSD or CPTSD don’t behave like the traumatized characters in this story. In many ways, it felt like a kind of wishful fantasy of how nice it would be if people who had been severely traumatized could recover in a relatively short time and in a straightforward way. Even taking some time to research how CPTSD and PTSD can affect trauma survivors could have helped the author write more realistic characters. They were overall too successful, healthy, and emotionally consistent, and said and did too many “right” things the “right” way. Conversely, when the perpetrators did things or said things, they were often too horrid and almost cartoonishly villainous.
There were a handful of ambiguous folks who defied being neatly categorized as “bad” or “good” but the central cast of characters were largely a flat and static bunch.
Nobody seemed to grow as a person or overcome any personal flaws, except for a couple of peripheral characters, and that growth happened largely off-page and was revealed at the end of the story rather than showcased as a central aspect of the book.
In terms of pacing and the twistiness of the plot itself, it was very fast-paced and intense. It was a creative story full of mysteries to solve. Many times I couldn’t pull myself away from reading it because I was so curious about how things would unfold and what was really going on.
Overall, I found it to be an interesting read, but the unconvincing way the characters behaved, in light of how real live people respond to trauma, kept taking me out of the story and making me occasionally roll my eyes or shake my head at the cluelessness of the portrayal of traumatized people.
It would require some spoilers to get more specific than that. If you don’t mind shallowly sketched characters who seem to be permanently locked into their “good guy” or “bad guy” identities, and you enjoy fast-paced thrillers with twisty plots and convoluted storylines, this one is worth your time. I wouldn’t recommend it to most of the people I personally know, though, for the reasons I mentioned.
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Reviewed in the United States on October 12, 2025
★★★★★ 4
A high stakes political agenda
Format: Kindle
Cami was about to embark on her college years with her boyfriend when she found out she was pregnant. Worse than that was when she arrived home and was ambushed by two men who had already tied up her mother and younger sister. Knowing nothing good could come from this ordeal Cami planned to escape her captivity.
…
Rex had been running when he saw police activity near Cami’s neighborhood. Concerned for her well-being he went to investigate. He shouldn’t have gotten involved because he became a suspect and now the community looks at him as a dangerous criminal eventhough he was cleared of any wrongdoing. The scholarship program that was supposed to be his escape from this community was revoked so he enlisted in the military.
…
Mia Sheridan certainly knows her way around a good emotional read. Trauma of this magnitude can only be explained by a seasoned writer. I appreciated this well thought out storyline. The writing was strong, yet I still found myself not completely invested. There were high points and low points where my interest would waver depending upon the content. This started off with an intense scene that I thought would carry over the entirety of the story. The story had a shift that disrupted the pace. I had to regroup my thoughts. The content was tragic and while I appreciated the concept I didn’t like the execution in certain places. There were many layers to this story that were kept from the reader to serve a purpose later on. Overall, The Fix was a book about survival and how women are capable of greatness.
…
The Fix offers a balance of tragedy with hope not pushing too much in either direction. The dark balances with the light carving the way towards a future filled with happiness.
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Reviewed in the United States on October 27, 2025
★★★★★ 5
Great read...
Format: Kindle
Couldn't put this down. Characters are relatable and the plot twists keep you guessing through out the story. And who doesn't love a happy ending...?!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 31, 2026