Mucky Nutz MugGuard Fender Keeps Dirt off Your Rear (Shock)

The Mucky Nutz MugGuard rear fender is designed to keep your shock and/or back side mud- and dirt-free.
The Mucky Nutz MugGuard with the full extension installed.

No matter where you live in the world, there’s a good chance it’s mud season right now; if not, mud season is surely on the way. As mountain bikers we always try to avoid riding muddy trails, but that says nothing of muddy two track and puddles that linger long after the rain is gone. The Mucky Nutz MugGuard is a new rear fender designed to not only keep your backside clean, but your mountain bike running smoothly too.

Mucky Nutz MugGuard installation and fitting

The MugGuard is made from 100% recycled plastic which is pretty great news given that only about 5% of recycled plastic is used to make new products. Not only that, the fender is itself recyclable once it has reached the end of its useful life. The UK-made kit comes with a two-piece fender, mounting brackets, various plugs, and “reusable VELCRO® fasteners.”

The brackets attach to the lower fender segment via a cogged system that makes it easy to align both sides evenly using dots imprinted on the two pieces. A rubber strip sits between the mount and your seat stays to protect paint, though I would still recommend adding some kind of frame protection, preferably with an anti-slip surface, to ensure the mounts don’t slide down the stays when the trail gets wet and rowdy.

The guard just fit in between the seat stays on the Canyon Lux Trail that I’m testing. If your frame can fit rear tires 2.4″ wide or wider, the Mucky Nutz MugGuard should work. The brand says the fender will fit 26″ to 29″ tires and widths up to three inches. I tested mine with a 29×2.35″ tire.

I used zip ties to attach the guard rather than using the included fasteners. The Velcro fasteners seem a little fussier than regular old zip ties, but that could just be a personal preference. The fender pieces weigh about 260g altogether.

Shown without the extension. The orange mud splatter on the seat tube seen here came from an earlier ride before the Mucky Nutz MugGuard was installed.

On the trail and in the mud

With the full guard installed I was worried that jumps and bumps would cause the Mucky Nutz MugGuard to rub the tire or at the very least, that the fender would rattle around. There was a little noise at first, but once everything settled into place the guard stayed mostly quiet. On the rare occasions when it did clatter and clank it was because a stick tried to get in between the tire and fender, or when a clump of dirt flung itself against the inside of the guard.

Half fender

A two-piece fender, the primary, lower section is basically meant to keep dirt off the bike’s shock and any frame-mounted water bottles. A lot of bikes, including the Canyon I’m testing, are susceptible to mud collection around the lower linkage too, and sadly this type of fender isn’t much help as you can see in the photo and animation above. If you want to protect the lower linkage, you’ll likely need to find a fender designed specifically for your frame; some bikes come with one pre-installed.

Full fender

Mucky Nutz notes the fender extension is designed for the muddiest days, and it’s clearly very effective at keeping pretty much the entire seat tube mud-free, including the dropper post. The extension also has the advantage of keeping the back of your pants and jersey mud free (tested) but still deposits mud around the lower linkage.

Based on these tests I’ll likely ride with the full fender with the extension even if it might look like overkill. Clearly the extension provides a lot more protection.

Pros and cons of the Mucky Nutz MugGuard


  • Quality materials and design makes installation simple
  • Should fit most bikes
  • Stable and good coverage; ensures components and clothing stay relatively clean


  • With the extension, the fender looks like it belongs on a commuter bike (I got a lot of comments)
  • The mounts tend to slide a bit on the frame. I recommend protecting your frame first with tape or an old tube to prevent slippage.

Bottom line

The Mucky Nutz MugGuard is a useful accessory to protect your shock and dropper post during mud season, and to keep your rear end clean on the yuckiest rides.

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