Shimano RD-TY21B Bike Rear Derailleur 6/7 Speed

  • TY21B-direct mount
  • TY21B-hanger mount

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Shimano RD-TY21B Bike Rear Derailleur 6/7 Speed

Shimano RD-TY21B Bike Rear Derailleur is a reliable and durable component designed to enhance the performance of your 6-7 speed bicycle. It features a Direct Mount design for enhanced stability, is easy to install and adjust, and provides smooth and precise shifting. Compatible with a wide range of bicycle models, this rear derailleur is an excellent choice for riders looking to upgrade their bike's shifting performance.


  • MODEL: Shimano RD-TY21B
  • PERFORMANCE: Forged with high-hardness aluminum alloy. The hollow weight-reduction design is adopted, and the speed change is more stable.
  • PRECISE ADJUSTMENT: High-hardness aluminum alloy body adjustment, adjustment is more precise. It can be adjusted slightly in multiple places to ensure accurate speed change performance.
  • INSTALLATION: Fast and convenient installation and easy maintenance. (Note: The bike's rear derailleur includes a direct mount and a hanger mount. Please check the mount type of the original part before ordering.)
  • SCOPE OF APPLICATION: Suitable for mountain bikes, station wagons, folding bikes, etc.


Model Shimano TY21B,  Black
Speed grade 6 speed/7 speed
Installation method Direct mount and hanger mount
Weight About 267g
Application  Suitable for mountain bikes/folding bikes/road bikes/variable speed bikes

Customer Reviews

Based on 15 reviews
William Duron
Quality product

I received it when promised, Fits with no additional adjustments required on my part. Good quality product, sturdy and works as it should.


I was mistaken about this being misadvertized.

joe gamble
Solid job.

Used this to replace a damaged more expensive one. I do a bit of off road cycling and it works perfect. But im not that brave. This is perfect for a comutor bike.

Ordinary quality

The quality is so-so. It is just an imitation of Shimano. Considering the price, it may be good to use it temporarily. Note the plastic parts will be easy to destroy.

Amazon Customer
fit perfect

worked great

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What should I consider when choosing bicycle tires?

When selecting bicycle tires, consider the size, tread, width, durability, pressure, weight, and riding style. Choose a tire that fits your bike's wheels, is appropriate for the terrain you'll be riding on, is durable and puncture-resistant, can handle the recommended tire pressure, and matches your riding style.

What size bike tire do I need for my bike?

To determine the size of tire you need for your bike, you can look at the sidewall of your current wheel, which will have the tire size printed on it. The size will typically be expressed as a combination of numbers and letters, such as "700x23c" or "26x2.0". The first number refers to the diameter of the tire, which is measured in millimeters for metric sizes (e.g. 700) or inches for imperial sizes (e.g. 26). The second number refers to the width of the tire, also measured in millimeters or inches. The letter at the end indicates the type of tire (e.g. "c" for clincher)
If you're unsure about what size tires to get or have any doubts about compatibility, you can consult your bike's owner's manual or contact the manufacturer for advice.

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