Over 2,000,000 Million Customers Served!!!

Need Help? Click the Live Chat to Talk to a Gearhead 💪

Enjoy Free Shipping on Orders Over $75 – Available Within the Lower 48 States!

SKU: CR3487

Shimano BB-UN300 Square Taper Bottom Bracket | JIS 68x118mm Hollow Spindle, BSA (English) Bike Crankset Compatible, Durable Steel Construction for Road & Mountain Bikes

Regular price $15.43
$18.00 Sale price $15.43 Regular price
Sale Sold out
Unit price
/per 
Save 14%
  • Free Shipping Over $75
  • 30 Day Returns
  • Satisfaction Guaranteed!
Get 10% Off When You Buy 2!

$10 Gift Card

at 250 points

$25 Gift Card

at 500 points

$75 Gift Card

at 1,000 points

This is a pre order item. We will ship it when it comes in stock.

$10 Gift Card

at 250 points

$25 Gift Card

at 500 points

$75 Gift Card

at 1,000 points

Description
Specifications

Upgrade your bicycle's performance with the Shimano BB-UN300 Square Taper JIS Bottom Bracket, a reliable and durable component designed for seamless power transfer and smooth pedaling. Crafted from high-quality materials, this bottom bracket features a hollow spindle construction that enhances stiffness and weight savings, ensuring efficient energy transmission during every ride.

Materials & Engineering:

Constructed from precision-machined steel, the Shimano BB-UN300 offers exceptional durability and corrosion resistance. The hollow spindle design reduces weight without sacrificing strength, making it ideal for both recreational and competitive cyclists. The 1.37-inch JIS square-taper interface ensures a secure and precise fit with compatible cranksets.

Components & Technology:

Engineered for compatibility with JIS (Japanese Industrial Standard) square-taper cranksets, this bottom bracket supports a spindle length of 118mm and fits 68mm wide shell bikes. Easy to install with separate crankarm fixing bolts, it provides a stable foundation for your crankset, ensuring consistent power delivery and long-lasting performance.

Style & Use Case:

Available in sleek black, the Shimano BB-UN300 is suited for a variety of bicycle styles-from mountain bikes and hybrids to commuter bikes-offering dependable performance for daily rides, mountain adventures, or endurance cycling. Its straightforward design makes it a perfect replacement or upgrade for bikes needing reliable bottom bracket performance.

Innovative & Differentiating Features:

This bottom bracket's precise engineering and compatibility with square-taper cranksets make it a versatile choice for cyclists seeking a low-maintenance, high-quality component. Its hollow spindle technology not only reduces weight but also improves durability, setting it apart from standard models.

Key Specifications:

- Fits JIS Square Taper cranksets with 118mm spindle length

- Suitable for 68mm shell width frames with 1.37 shell diameter

- Designed for English (BSA) threaded bottom bracket shells

- Complete your bike's drivetrain with confidence, knowing you have a high-performance Shimano component for smooth, efficient riding.

Optimize your bicycle's performance today with the Shimano BB-UN300 Square Taper JIS Bottom Bracket-engineered for durability, efficiency, and seamless compatibility.

  • High-quality, durable construction with a hollow spindle design for enhanced lightweight performance and increased pedaling efficiency.
  • Compatible with JIS square-taper cranksets, making it ideal for a wide range of traditional and classic bicycle builds.
  • Precision-engineered for optimal rotational smoothness and longevity, ensuring reliable power transfer on every ride.
  • Designed for BSA (English) frame shells with a 68mm shell width and 118mm spindle length, providing a perfect fit for versatile road and mountain bikes.
  • Sleek black finish and straightforward installation make this bottom bracket a stylish, high-performance upgrade for your cycling setup.
Bottom Bracket Shell I.D.1.37
BB/Frame InterfaceEnglish
BB Shell Width (mm)68
Spindle Interface TypeSquare Taper JIS
Spindle Length118
Defined ColorBlack
Shipping
Returns
About Us
Contact Us

We pride ourselves on our ability to ship and deliver your gear with excessive speed! We ship from 22 locations throughout the United States and most orders will arrive in 3 days or less with Free Shipping on orders over $75!

The nitty gritty, for specific delivery timelines please pay attention to the delivery timelines on the product pages and the time frame estimated in the carts. If you need a part by a specific day, please contact us by chat, phone, or

Chat

Talk with a representative

Start Chat

Email

info@365cycles.com

Send Email

Phone

603-968-5797

Call Now

Most orders placed during the workweek before 1:00 PM Eastern time ship the same day, but during peak/holiday season or depending on inventory location handling time can take up to 48 hours. If you have questions regarding shipping estimates, don't hesitate to get in touch with us before placing the order. There is a direct signature requirement for all orders over $500.

We provide the you the ability to utilize multiple shipping & billing addresses, based upon what fits your current needs. However you are responsible to maintain and update any new address changes, as 365 Cycles will not be held liable for orders being shipped to an incorrect address.

  • Our Mistake: If we messed it up you can rest assured we are going to make it right. Contact us by email, phone, or chat and we will make your head spin with how quick we fix it
  • Warranty: We are an authorized retailer for everything we sell, so rest assured your product is covered under the manufacturer's warranty. Contact Us if you are having an issue and we will make sure you are taken care of
  • Just don't want it anymore: We have a 30-day return policy for orders within the US. We offer refunds on returned items that are brand new and in their undamaged, original packaging. Customers are responsible for the cost of return shipping. Damaged, installed, and used items as well as those without original packaging are not eligible for returns. If it's returned in this condition it may be denied and sent back to you

If you need to return your order please email us at info@365cycles.com, call us at 603-968-5797, or use the live chat on our site.

Chat

Talk with a representative

Start Chat

Email

info@365cycles.com

Send Email

Phone

603-968-5797

Call Now

*Please allow up to 3 business days for us to process your return*

365 Cycles puts the customer above everything. Our number one goal is your satisfaction. When you press the shift lever you want the gears to shift, and when you buy bicycle parts, you want the bicycle parts to arrive on time in new condition. With over 60,000 products and 22 warehouse locations throughout the country, we have the parts you need and they are coming in hot!

Living an active lifestyle is just that, a lifestyle that never goes away and our goal is to always exceed your expectations so we can take this lifelong journey together. We strive to have the parts you need, at competitive prices with unmatched shipping speeds!

If there is ever an issue with an order we will work at warp speed to fix our mistake and make sure you never go a day without a bicycle! If you are not receiving the quality of service you need from one of our exceptionally qualified bicycle experts, tell them Ben Berman told you to tell them "Customer Loyalty" and then name your terms.

Our team is waiting to help you 7 days a week and they are more qualified to help than I am but if you ever feel like you're not getting the service you need I’m personally asking you to email me at ben@365cycles.com with "CUSTOMER LOYALTY" in the title and I will personally handle your order.

Over the years we have served millions of satisfied customers and continue to serve many of them today. With your feedback, we are confident we can take this lifelong journey together and build a friendship that goes beyond parts and accessories.

“If you want to go fast, go alone, if you want to go far, go together.” -Someone Smart

Ben Berman Founder & CEO of 365 Cycles


Company Core Values: 

These were established by the members of our team and we use them every week to call out team members who have shined in one of these areas. Feel free to let us know at info@365cycles.com if someone you worked with has gone above and beyond in one of these areas. 

Customer Loyalty

Put yourself in their shoes and support those who support us.

You Control the Outcome

If it is to be, it’s up to me" You are personally responsible for controlling the outcome.

Seek Understanding

Understanding the answer is more important than the answer.

Progress Not Perfection

Pick a direction, analyze the results, and be willing to change course.

Will to Win

Customers, 365 Team, Partners, all need the will to win. Bring the Will to Win to every conversion.

Keep Moving

Move the body, move the mind, and remove any hurdles to achieving an active lifestyle.

Do the Right Thing:

Doing the right thing is more important than doing the thing right.

Stronger together:

If you want to go fast, go alone, if you want to go far, go together. Get your team involved and become stronger together.

Chat

Talk with a representative

Start Chat

Email

info@365cycles.com

Send Email

Phone

603-968-5797

Call Now

Customer Reviews

Based on 10 reviews
100%
(10)
0%
(0)
0%
(0)
0%
(0)
0%
(0)
S
Steve

Was easy to install. Only thing I would have liked is a torque spec.

A
Amazon Customer

The fine threads are very easy to cross thread and you will learn how to use a a mini triangle file if you're not careful. Once installed you'll love it.

C
Customer

The fine threads are very easy to cross thread and you will learn how to use a a mini triangle file if you're not careful. Once installed you'll love it.;

m
mgrif

Excellent reliable bottom bracket. I have used them on several bikes. I got another make last time...it turned stiffly and started to creak after a certain time of seasons. I expect this one to last many years.

m
mgrif

Excellent reliable bottom bracket. I have used them on several bikes. I got another make last time...it turned stiffly and started to creak after a certain time of seasons. I expect this one to last many years.;