

⚡ Shift Faster, Ride Smarter — Own Every Terrain
The microSHIFT M21 Rear Derailleur is a lightweight, durable, and precision-engineered component designed for 6- and 7-speed road and mountain bikes. Featuring a super short cage and corrosion-resistant black finish, it delivers smooth, rapid gear changes with seamless compatibility across various drivetrains. Ideal for riders seeking reliable performance and sleek aesthetics in all riding conditions.
| Manufacturer | microSHIFT |
| Global Trade Identification Number | 04710495436388 |
| Item Package Dimensions L x W x H | 6.97 x 5.43 x 2.48 inches |
| Package Weight | 0.3 Kilograms |
| Item Dimensions LxWxH | 6.5 x 6 x 3 inches |
| Brand Name | microSHIFT |
| Warranty Description | Limited Warranty |
| Model Name | 4710495436388 |
| Suggested Users | Does Not Apply |
| Number of Items | 1 |
| Part Number | RD-M21SS |
| Style | Rear Derailleur |
| Included Components | Rear Derailleur |
| Size | Super Short Cage |
B**S
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.
T**!
20-in mountain bike must have!
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!
D**S
Fast, smooth shifting. Much better than Shimano at this price point.
The derailleur body and internals are made primarily of steel, including where the set screws are used to set top-bottom range. This made the setup easy and gives a sense of durability. At this price point, everything on a Shimano derailleur is plastic. This Microshift setup shifts fast and smooth and I like the compact, short cage design. Initial rides have been really enjoyable. Nice replacement for lower end Shimano derailleur.
N**E
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.
U**1
Easy to tune, quiet, and a good fit for 7 speed drivetrains.
Good for 7 speed. It is quiet and easy to tune.
D**D
Improved ground clearance
I put these on my 20" ebike and greatly increased the ground clearance of the derailleur over the stock unit. You will have to break the chain for these though as the rollers are not removable.
W**I
Short 7 Speed Cage
This works great. Replaced a long cage for a kids bike. Nice fit.
J**Y
Great value
Short of not having a clutch, it’s perfect. What a great deal. I use these on all the seven speeds I repair.
Trustpilot
2 weeks ago
1 month ago