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: CR3488

Shimano BB-UN300 Square Taper JIS Bottom Bracket with 47.5mm Chainline, 68mm Shell Width, Hollow Spindle for BSA Frames, Durable Black Finish, Compatible with JIS Square Taper Cranksets, Precision Performance Cycling Component

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

High-Performance Shimano BB-UN300 Square Taper JIS BSA Bottom Bracket - 68x122.5mm Chainline

Upgrade your bicycle's drivetrain with the Shimano BB-UN300 Square Taper JIS BSA Bottom Bracket, expertly engineered for durability, reliability, and smooth pedaling performance. Designed to fit JIS square-taper cranksets seamlessly, this bottom bracket offers a perfect balance of engineering innovation and versatile compatibility for a wide range of cycling styles.

Materials & Construction:

Constructed with high-quality materials, the Shimano BB-UN300 features a precision-machined hollow spindle that reduces weight without sacrificing strength. Its robust metal components are corrosion-resistant, ensuring longevity even in harsh riding conditions. The sleek black finish not only provides a timeless, professional look but also adds extra protection against wear.

Performance & Engineering:

Built for superior rotational efficiency, this bottom bracket ensures smooth bearing operation to maximize power transfer and pedaling comfort. The 47.5mm chainline aligns your crank effectively for optimal clearance and stability, enhancing overall ride quality. The hollow spindle design contributes to reduced weight, helping you achieve faster acceleration and improved climbing ability.

Components & Technology:

Utilizing Shimano's proven square-taper JIS interface, the BB-UN300 guarantees compatibility with a wide array of crankarms and bike frames with a 68mm shell width. The precise fit reduces wobble and promotes consistent performance. Please note that crankarm fixing bolts are sold separately, allowing for flexibility to select the ideal hardware for your setup.

Style & Use Case:

Ideal for mountain bikes, hybrid bikes, and touring bicycles, the Shimano BB-UN300 is a versatile choice for cyclists seeking reliable performance and easy installation. Its durable construction makes it suitable for daily commuting, long-distance rides, or rugged trail adventures. The sleek black aesthetic complements any bike design, blending functionality with style.

Innovative & Differentiating Features:

- Hollow spindle design for lightweight strength

- 47.5mm chainline for optimal crank alignment

- Precision JIS square-taper interface for compatibility and stability

- Corrosion-resistant materials for long-lasting performance

- Easy installation and maintenance

Upgrade your bicycle's bottom bracket with the Shimano BB-UN300 Square Taper JIS BSA Bottom Bracket - the perfect choice for reliable power transfer, smooth spinning, and durable performance. Ensure your bike runs at peak efficiency with this high-quality, SEO-optimized component designed for serious cyclists and bicycle shop professionals alike.

  • Precision-engineered Shimano BB-UN300 Square Taper JIS Bottom Bracket with 68x122.5mm shell ensures smooth power transfer and reliable performance for your mountain and road bikes.
  • Constructed with high-quality materials and a hollow spindle design, this bottom bracket offers enhanced durability, lightweight performance, and optimal stiffness for aggressive riding.
  • Designed to fit JIS square-taper cranksets with a 47.5mm chainline, providing seamless compatibility with a wide range of Shimano and third-party cycling components.
  • Features a standard 68mm shell width and English bottom bracket interface, making installation straightforward and compatible with various frame types for versatile use.
  • Innovative engineering with precision machining and corrosion-resistant components ensures long-lasting performance and consistent pedaling efficiency in all riding conditions.
Bottom Bracket Shell I.D.1.37
BB/Frame InterfaceEnglish
BB Shell Width (mm)68
Spindle Interface TypeSquare Taper JIS
Spindle Length122.5
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 20 reviews
85%
(17)
0%
(0)
15%
(3)
0%
(0)
0%
(0)
C
Charlie

I purchased this shimano bottom bracket after trying 2 different cheap units that didn't last. I'm extremely happy as the operation is whisper quiet. I'll definitely buy this again if needed in the future.

Also deliver was as expected.;

S
Satisfied User

This product was exactly as in the description and arrived on time. The installation instructions were clear and easy to follow. After installation was complete IÔøΩve done a few spins and it is working perfectly!

S
Satisfied User

This product was exactly as in the description and arrived on time. The installation instructions were clear and easy to follow. After installation was complete IÔøΩve done a few spins and it is working perfectly!

S
Satisfied User

This product was exactly as in the description and arrived on time. The installation instructions were clear and easy to follow. After installation was complete I’ve done a few spins and it is working perfectly!;

S
Some Programmer

I bought this to replace the troublesome cup and cone bottom bracket on my Schwinn GTX 3 and it's a big improvement. The bike pedals noticably smoother now and no longer clicks under load.