Search  for anything...

Master Lock 8170D, 6-1/8 inch Wide U-Lock with 8" Shackle, Black

  • Based on 4,976 reviews
Condition: New
Product info up-to-date
$18.98 Why this price?
Save $260.91 was $279.89

Buy Now, Pay Later


As low as $4 / mo
  • – 4-month term
  • – No impact on credit to apply
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Apple Pay, and PayTomorrow. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

FREE 30-day refund/replacement

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.


Availability: In Stock.
Fulfilled by Amazon

Arrives Tuesday, Jun 16
Order within 18 hours and 51 minutes
Available payment plans shown during checkout

Protection Plan Protect Your Purchase
Checking for protection plans...

Size: 6-1/8 inch U-Lock


Style: Lock


Features

  • Outdoor heavy duty bike U-lock is best used as a bicycle lock.Note: Measure your door's backset, cross bore and thickness to ensure you find the right fit.
  • U-shaped steel bike lock with key; Includes carrier bracket for easy transportation
  • Bike lock features a hardened steel body and double locking shackle for superior cutting and prying resistance
  • Bike lock body is 6-1/8 in. (16 cm) wide, with 8 in. (20 cm) shackle length, 4 in. (10 cm) width and 1/2 in. (13 mm) diameter
  • Includes one u-lock bike lock, two keys

Description

The Master Lock U-Lock is engineered for those who value their ride. This bicycle lock offers unparalleled security to ensure your bike stays right where you left it. It is crafted from hardened steel that can withstand significant impacts and resist all manner of attempts at tampering or cutting. This makes it an exceptional choice among bike locks for anyone serious about anti-theft security. The bike lock body is 6-1/8-inches wide with an 8-inch shackle length. Whether you are locking up your bicycle in a bustling urban environment or a quieter suburban area, trust that this heavy-duty bike lock has you covered. Its imposing presence alone deters would-be thieves before they even think about attempting anything nefarious. But what sets this U-lock bike apart from others? The answer lies in its intuitive design and ease of use. Despite its strength and durability, the Master Lock 8170D U-Lock is incredibly user-friendly. It boasts a double-locking mechanism providing twice the security while ensuring quick access when you need to unlock it swiftly. Lightweight yet sturdy, this U-lock fits easily into most backpacks or bike accessory bags without weighing you down. Investing in the Master Lock U-Lock means investing in long-term security for your precious ride. Unlock superior protection now with Master Lock: where studied design meets impenetrable strength.

Brand: Master Lock


Special Feature: Heavy Duty


Lock Type: Key Lock


Item dimensions L x W x H: 9.8 x 7.33 x 1.33 inches


Material: Alloy Steel, Rubber


Brand Name: Master Lock


Recommended Uses For Product: Bike


Number of Pieces: 1


Included Components: U-lock bike lock, two keys, and a carrier bracket


Model Number: 8170D


UPC: 071649222771


Model Name: 8170D


Global Trade Identification Number: 71


Manufacturer Warranty Description: Limited Lifetime Warranty


Manufacturer: Master Lock


Unit Count: 1.0 Count


Manufacturer Part Number: 8170D


Item Type Name: U Lock


Additional Features: Heavy Duty


Lock Type: Key Lock


Controller Type: Hand Control


Control Method: Touch


Smart Home Compatibility: Not Smart Home Compatible


Style Name: Lock


Color: Black


Shape: U Shape


Material Type: Alloy Steel, Rubber


Finish Types: Vinyl Coating


Item Dimensions: 9.8 x 7.33 x 1.33 inches


Item Weight: 2 Pounds


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Jun 16

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • PayTomorrow Financing
  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Top Amazon Reviews


  • Secure lock to prevent theft!
Size: 6-1/8 inch U-Lock Style: Lock
Great lock. Needed it for my scooter and never failed me once over 1 year of use. Couple of my friends had a wire lock and their scooters unfortunately got stolen. The lock is very durable, and it comfortably fit around my scooter with no struggle. Also, had to ship the lock across the country in the same box as the scooter and it did get banged up a bit with visible scratches but it didn't affect the durability at all! Ended up forgetting my key at times too, but luckily they give a backup key! Only concern would be that the key is annoying to use sometimes, but never bothered me in any significant way. Definitely recommend. ... show more
Reviewed in the United States on September 26, 2025 by Mr. Beast

  • Very effective! Very effective!
Size: 7-1/4 inch U-Lock Style: Lock
This lock saved my scooter from getting stolen! It was bent out of shape but never broke! It had to be cut off so I am ordering a replacement now! I highly recommend!
Reviewed in the United States on June 9, 2026 Reviewed in the United States on June 9, 2026 by Amazon Customer

  • Great lock for your bike love it love it love it
Size: 7-1/4 inch U-Lock Style: Lock
I love this lock. This lock is amazing. Great for leaving your bike unattended while you shop or do any other activities away from your bike. Love it love it love it.
Reviewed in the United States on April 30, 2026 by King Davis

  • Does the job Does the job
Size: 7-1/4 inch U-Lock Style: Lock
Does what it needs to in keeping my bike locked up, so to that it works well. Fits under my seat. Side opening lock rather than bottom so it's easier to access when under my seat. My only complaint, is how thick the top plastic part of the keys are. I don't mind a thick key but the housing was a pain to get onto my keychain since its about 3 keys wide (5mm). The piece above the opening is also slightly large and so I had to use something to pry my keychain opening enough to slip it in. A little niche of an issue I'm sure but my issue none the less since my keyring is also slightly thicker and tighter than others. Looking past that it works fine and feels sturdy enough to last a while. ... show more
Reviewed in the United States on August 17, 2025 Reviewed in the United States on August 17, 2025 by Chaykim

  • Works well
Size: 7-1/4 inch U-Lock Style: Lock
Secure ..adjustable with locking chain..looks intimidating..
Reviewed in the United States on May 16, 2026 by Customer

  • Good/great for the price!!
Size: 7-1/4 inch U-Lock Style: Lock
Easy to lock and very sturdy lock and key. I know I feel safe with this.
Reviewed in the United States on May 22, 2026 by Vanessa Hollenbeck

  • Good bike lock.
Size: 6-1/8 inch U-Lock Style: Lock
Good deal for a master lock product is always a safe bet. Like literally never bought a bad master lock product that just doesn’t happen as a general rule of thumb. I feel like this will do better for safety against theft then just a regular wired bike locks are easy to cut through for thieves.
Reviewed in the United States on March 8, 2026 by Honest consumer

  • Decent U-Lock but Locking Mechanism Could Be Better
Size: 6-1/8 inch U-Lock Style: Lock
I recently bought the Master Lock 8170D U-Lock, and my experience has been a bit mixed. The lock feels sturdy and solid, providing a decent level of security for my bike. The 6-1/8 inch size is convenient, making it easy to lock up my bike frame and wheel to most bike racks. The black color is sleek and blends in well with my bike’s aesthetic. However, I've had some issues with the locking mechanism. It can be a bit finicky, requiring multiple tries to get it to lock or unlock. This is frustrating, especially when I'm in a hurry. The keys also feel a bit flimsy, which raises concerns about long-term durability. While the Master Lock 8170D provides basic security and is easy to carry around, the unreliable locking mechanism is a downside. It’s a decent lock for low-risk areas, but I would recommend looking for a more reliable option if you need maximum security. Three stars! ... show more
Reviewed in the United States on August 29, 2024 by Darshil

Can't find a product?

Find it on Amazon first, then paste the link below.