---
product_id: 204469439
title: "M21 Rear Derailleur - 6,7 Speed, Super Short Cage, Black"
brand: "microshift"
price: "243 kr"
currency: DKK
in_stock: true
reviews_count: 10
category: "Micro Shift"
url: https://www.desertcart.dk/products/204469439-m21-rear-derailleur-6-7-speed-super-short-cage-black
store_origin: DK
region: Denmark
---

# Super short cage, 241g lightweight High-strength composite & steel 6-7 speed compatible M21 Rear Derailleur - 6,7 Speed, Super Short Cage, Black

**Brand:** microshift
**Price:** 243 kr
**Availability:** ✅ In Stock

## Summary

> ⚡ Shift Fast, Ride Faster — Upgrade Your Ride with microSHIFT M21!

## Quick Answers

- **What is this?** M21 Rear Derailleur - 6,7 Speed, Super Short Cage, Black by microshift
- **How much does it cost?** 243 kr with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.dk](https://www.desertcart.dk/products/204469439-m21-rear-derailleur-6-7-speed-super-short-cage-black)

## Best For

- microshift enthusiasts

## Why This Product

- Trusted microshift brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Sleek & Stealthy:** Matte black finish blends style with corrosion resistance, perfect for the discerning rider.
- • **Compact Powerhouse:** Super short cage design optimizes chain wrap and maximizes road clearance for urban and trail agility.
- • **Effortless Integration:** Standard 10x1 mount fits most bikes, making upgrades and replacements hassle-free.
- • **Durability Meets Agility:** Robust composite and steel build ensures long-lasting performance without the weight penalty.
- • **Precision Shifting Mastery:** Seamlessly shifts across 6- and 7-speed systems for flawless gear transitions.

## Overview

The microSHIFT M21 Rear Derailleur is a lightweight (241g), super short cage drivetrain component engineered for 6- and 7-speed road and mountain bikes. Combining high-strength composite and steel materials, it delivers precise, rapid gear changes with a max cog size of 32 teeth. Its sleek black finish and standard 10x1 mounting make it a durable, stylish, and easy-to-install upgrade for riders seeking responsive shifting and enhanced ride efficiency across diverse terrains.

## Description

Boost Your Bike's Performance with the microSHIFT M21 Rear Derailleur - 6 & 7-Speed, Super Short Cage, Black Upgrade your cycling setup with the microSHIFT M21 Rear Derailleur, engineered for versatility, durability, and smooth shifting. Designed to work seamlessly with 6- and 7-speed road and mountain bike systems, the M21 rear derailleur is the perfect choice for cyclists seeking reliable performance across various terrains and riding styles. Materials & Construction: Constructed with robust composite materials combined with high-strength steel components, the M21 derailleur offers exceptional durability and lightweight performance. Its corrosion-resistant black finish not only enhances the aesthetic appeal but also ensures longevity in diverse weather conditions, making it ideal for everyday commuting, mountain biking, or gravel adventures. Performance & Engineering: Featuring a super short cage design, the M21 derailleur provides precise gear indexing and rapid shifting response, especially suited for bikes with a 32-tooth largest cog. The optimized engineering ensures optimal chain wrap capacity of 21 teeth, reducing chain slack and minimizing derailleur noise for a quieter, more efficient ride. Its innovative design guarantees smooth transition between gears, even during aggressive riding or rough terrain. Components & Technology: Equipped with a 10x1 standard rear derailleur mount and compatible with 6- and 7-speed systems, the M21 offers effortless installation and compatibility with a wide array of bikes. Whether you ride a mountain bike, road bike, or hybrid, this derailleur provides dependable performance with easy-to-adjust components for maintenance and tuning. Style & Use Case: The sleek black finish and compact profile make the microSHIFT M21 rear derailleur both stylish and functional. Its lightweight (just 241 grams) construction makes it suitable for riders prioritizing agility and speed. Perfect for upgrading existing bikes or bui

Review: Hard to believe that such an inexpensive product could be such an improvement - I purchased an old Tern Link seven speed folding bike that was a complete wreck. Among other issues, the Shimano Tourney derailleur was a blob of rust. After I wasted money derusting it, purchasing a new pivot bolt and shims for the pivot bolt, etc., I noticed that there was a lot of friction when trying to pedal. Turns out the derailleur had been bent in an accident and was at an angle to the rear wheel, inducing drag. The bike has only a singe chainring on the crank and the rear is 14-28T (28 minus 14 is only 14 tooth chain wrap capacity), so a short cage for quick shifts is ideal. Also, since the wheels on the bike are only 20" in diameter, it is desirable to have a short cage for as much road clearance as possible. It was a bit difficult finding a short cage derailleur at a decent price, but this one is great. It seems like by the time the Revoshift hits a new number, it has already shifted into that gear. I have many bikes and the Link is the one I want to use when I travel, as it folds, cost the least and looks like a beater so hopefully will be less prone to theft. But now it is the most responsive bike I have. It's really nice not having to wait for it to shift while negotiating traffic like with long cage derailleurs. The deraileur took around ten minutes to install. The cable feed is towards the bottom rear, so it needs more cable sleeve than the Tourney (where the feed was at the top rear). Fortunately, I had left a few extra inches of cable sleeve on the bike. Interestingly, around six inches of the the cable itself needed to be clipped off upon installation. There is very little naked cable after the sleeve enters the housing. So if you find the cable sleeve to be too short, you probably will only need a new sleeve but not a new cable. All in all, I was very happily surprised by the quality of this derailleur and the improvement it made on my bike.
Review: Nice compact derailleur - Works great on my kid’s 20” wheel bike. Paired it with a Shimano Tourney shifter (also recommended). Nice and compact compared to the original. Easy to set up and adjust.

## Features

- Ideal for 6- and 7-speed road and mountain bike systems, the microSHIFT M21 Rear Derailleur features a durable construction combining high-strength composite and steel components for reliable shifting performance.
- Designed with a super short cage and a maximum cog size of 32 teeth, this derailleur delivers quick, precise gear changes across a wide gear range, enhancing your ride efficiency on various terrains.
- Compatible with Mountain and Road shifters, the M21 rear derailleur offers seamless integration with your existing drivetrain components, ensuring smooth and responsive shifting under load.
- Constructed with a 10x1 standard mounting interface and weighing only 241 grams, this lightweight derailleur is perfect for aggressive trail riding, urban commuting, or all-around cycling adventures.
- Featuring a sleek black finish, the microSHIFT M21 combines performance-driven engineering with stylish aesthetics, making it an excellent upgrade or replacement for your bike's drivetrain.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B083WVF61S |
| Best Sellers Rank | #310,440 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #235 in Rear Bike Derailleurs |
| Brand Name | microSHIFT |
| Customer Reviews | 4.1 4.1 out of 5 stars (23) |
| Date First Available | August 6, 2019 |
| Global Trade Identification Number | 04710495436388 |
| Included Components | Rear Derailleur |
| Item Dimensions LxWxH | 6.5 x 6 x 3 inches |
| Item Package Dimensions L x W x H | 6.97 x 5.43 x 2.48 inches |
| Manufacturer | microSHIFT |
| Model Name | M21 Rear Derailleur |
| Number of Items | 1 |
| Package Weight | 0.3 Kilograms |
| Part Number | RD-M21SS |
| Product Dimensions | 12"L x 8"W x 2"H |
| Size | Super Short Cage |
| Style | Rear Derailleur |
| Suggested Users | Does Not Apply |
| Warranty Description | Limited Warranty |

## Product Details

- **Brand:** microSHIFT
- **Color:** Black
- **Item Weight:** 0.65 Pounds
- **Material:** Multi
- **Mounting Type:** Braze-On Mount

## Images

![M21 Rear Derailleur - 6,7 Speed, Super Short Cage, Black - Image 1](https://m.media-amazon.com/images/I/51eT-4kA5wL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Hard to believe that such an inexpensive product could be such an improvement
*by B***S on January 26, 2022*

I purchased an old Tern Link seven speed folding bike that was a complete wreck. Among other issues, the Shimano Tourney derailleur was a blob of rust. After I wasted money derusting it, purchasing a new pivot bolt and shims for the pivot bolt, etc., I noticed that there was a lot of friction when trying to pedal. Turns out the derailleur had been bent in an accident and was at an angle to the rear wheel, inducing drag. The bike has only a singe chainring on the crank and the rear is 14-28T (28 minus 14 is only 14 tooth chain wrap capacity), so a short cage for quick shifts is ideal. Also, since the wheels on the bike are only 20" in diameter, it is desirable to have a short cage for as much road clearance as possible. It was a bit difficult finding a short cage derailleur at a decent price, but this one is great. It seems like by the time the Revoshift hits a new number, it has already shifted into that gear. I have many bikes and the Link is the one I want to use when I travel, as it folds, cost the least and looks like a beater so hopefully will be less prone to theft. But now it is the most responsive bike I have. It's really nice not having to wait for it to shift while negotiating traffic like with long cage derailleurs. The deraileur took around ten minutes to install. The cable feed is towards the bottom rear, so it needs more cable sleeve than the Tourney (where the feed was at the top rear). Fortunately, I had left a few extra inches of cable sleeve on the bike. Interestingly, around six inches of the the cable itself needed to be clipped off upon installation. There is very little naked cable after the sleeve enters the housing. So if you find the cable sleeve to be too short, you probably will only need a new sleeve but not a new cable. All in all, I was very happily surprised by the quality of this derailleur and the improvement it made on my bike.

### ⭐⭐⭐⭐⭐ Nice compact derailleur
*by N***E on September 23, 2025*

Works great on my kid’s 20” wheel bike. Paired it with a Shimano Tourney shifter (also recommended). Nice and compact compared to the original. Easy to set up and adjust.

### ⭐⭐⭐⭐⭐ 20-in mountain bike must have!
*by T***! on November 16, 2023*

I received this bike without a rare derailleur as a donation to our ministry. I tried several derailles on it but none was fully functional. I could get them to shift but the bee screw adjustment would not line up and eventually the derailleur would move. upon installing this, I had to break the chain but everything lined up great plus I got an extra maybe 2 in of ground clearance. microshift is really smart to build this derailleur at a great price! other short cage you railers started at $35. no wonder they get cloned. this is my new favorite derailleur! please excuse the photos!

## Frequently Bought Together

- microSHIFT M21 Rear Derailleur - 6,7 Speed, Super Short Cage, Black
- Bike Chain Kit, Single/6/7/8/9/10/11/12 Speed Multi-Function Bike Mechanic Repair Kit, Chain Breaker and Bike Link Plier with Hook and 6 Pairs Bicycle Buckle, Reusable (6/7/8 Speed Bike Chain Kit)
- Thinvik 6/7/8 Bike Speed Freewheel 14-28T/14-34T/13-34T,Bicycle Freewheel,Multiple Freewheel,Bike Sprocket

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**Shop now:** [https://www.desertcart.dk/products/204469439-m21-rear-derailleur-6-7-speed-super-short-cage-black](https://www.desertcart.dk/products/204469439-m21-rear-derailleur-6-7-speed-super-short-cage-black)

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*Product available on Desertcart Denmark*
*Store origin: DK*
*Last updated: 2026-02-09*