A friend of mine recently purchased a used hardtail mountain bike. As he showed it to me, I noticed that there's what looks like a koozie wrapped around the chainstay, towards the rear axle.

The branding on the koozie is the same as the make of the frame (Stevens), and it's being held on by velcro. It doesn't appear on the manufacturer's website as far as I can tell.

The outer layer seems like it's nylon, and there's some minimal padding.

What's the purpose of this thing, and what do you even call it?

I've included a photo for reference.

Photo of a bicycle's chainstay and rear drivetrain

  • What's the weird looking upstand aft of the seat stay? Looks like a bottle opener on a leg for a mudguard, or a kiddy's seat?
    – Criggie
    Commented Jul 6, 2017 at 12:07
  • That would be the pannier rack.
    – Jules
    Commented Jul 6, 2017 at 13:08
  • OK thanks - it looked really chunky compared to the ones normally seen.
    – Criggie
    Commented Jul 6, 2017 at 20:41

2 Answers 2


That is a "chain stay protector" and it is installed in, let us say, a non-traditional way. Typically it would be a couple inches forward of where it is.

As the name suggests, the purpose of the pad is to protect the chain stay from wear and damage from the chain, which can hit the stay with a lot of force when riding at high speed over rough terrain.

  • Normally, the chainstay is closer to the bottom bracket, because this is where the chain usually slaps the frame.
    – Borissov
    Commented May 8, 2016 at 7:39

Protects the chain-stay from the chain itself when taking the wheel out, be it for cleaning or whatever. Also stops the chain slapping it on bumpy roads or descents. Not sure what you'd call it, I'd just call it a chain-stay protector.

Some people use what's called Helicopter tape for the same purpose, too. I'd keep that thing on there, it then looks like the bike has a decent amount of protection from other components, and many mountain bikers respect that.

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