Mucky Nutz make some great, lightweight mudguards - check out the their Face Fender and Gut Fender ranges. The Rear Fender isn't one of them though. It is lightweight at 75g; it just isn't great.
The problem is the way that the Rear Fender attaches. The guard's flexible polypropylene material forms a U-shape where it fits to the seatpost. The U-shape is backed with rubber foam 'to prevent slippage', and a velcro strap holds it in place on the post. Mucky Nutz say it 'won't slip around the seatpost'. It absolutely will, and often.
I mostly tested it on a Kinesis Tripster ATR, on road and off, and pretty much every time I got off the bike I had to adjust it, as it had rotated from its six o'clock position directly behind me and over the rear wheel to five o'clock or seven o'clock, or worse. The underside of the guard had mud on it, like my backside, so it was doing something. It just wasn't doing it all of the time.
This isn't a problem unique to the Mucky Nutz Rear Fender. Every strap-on mudguard I have used has exhibited the same problem. I've snapped ratchets on those that have them, trying and failing to get them tight enough. The only quick-release seatpost-fixing guard I've used that has properly stayed in place is Zefal's Swan Road Mudguard.
There is another way to fit the Rear Fender, however. If you've got a space of about 5x3cm in the small triangle formed by the seat-stays and the seat-stay bridge, you can strap the Rear Fender to the top of the seat tube. (While the guard is wider than 3cm, it can be pinched inwards as it's flexible.) The seat-stays will then stop the Rear Fender rotating. I could get it on my 56cm fixed wheel bike like that, but the others had frames - generally 54cm or smaller - that were too compact or lacked the space between the seat-stays. But for bikes that are big enough, it's a good option.
Most purchasers will end up fixing it to the seatpost, I reckon, and there it's performance is underwhelming. A Zefal Swan guard will do a better job for road bikes or cross bikes, and a Crud Raceguard or Mudhugger Rear will do a better job on mountain bikes.
Poor attachment undermines the usefulness of this lightweight, strap-on mudguard
road.cc test report
Make and model: Mucky Nutz Rear Fender
Size tested: n/a
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Mucky Nutz say:
* Unique design providing full rear-end protection
* At 75g it is the lightest adjustable rear mudguard available.
* Compatible 99% of bikes, MTB, Road, CX......
* Adjustable, having three pitching options.�
* Compatible with dropper seatposts. Attach to seatpost or seat tube.
* Can be a permanent or temp item. Leave it on or fold flat, roll up and put it away.
* Won't slip around the seatpost. Has a rubber foam contact to prevent slippage.
* Quick release fitting.�
I say: it definitely will slip around the seatpost.
Tell us some more about the technical aspects of the product?
Material: Customized Polypropylene�
Lightweight, durable plastic. Poor, velcro-strap fixing.
Better than nothing. Not as good as other rear guards.
Springs back into shape easily.
Probably the lightest rear guard of this type and size available.
Tell us how the product performed overall when used for its designed purpose
Tell us what you particularly liked about the product
Tell us what you particularly disliked about the product
Rotated on the seatpost.
Did you enjoy using the product? No
Would you consider buying the product? No
Would you recommend the product to a friend? No
Anything further to say about the product in conclusion?
I'd only recommend it if you've got a bike big enough that it could fitted to the seat tube, or if you're prepared to bodge a more secure fit with cable ties... and probably glue.
About the tester
Age: 45 Height: 1.78m Weight: 67kg
I usually ride: Ridgeback Solo World fixed wheel My best bike is: Planet X Pro Carbon Track. Or Whyte M109
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, cyclo cross, commuting, touring, club rides, sportives, general fitness riding, fixed/singlespeed, mtb,