I posted this on another site quite a few years ago Feb 2016. Don't pay through the nose for an Extenda Fenda. Mine cost me 90c, made a card board template of the desired shape and size. Using the template I cut out the mudflap out of a 90c black plastic bucket, attach the mudflap with 3 X 4mm aluminium mushroom head Allen screws. Make sure the screws clear the tyre. You don't have to use black, buckets come in various colours. The reason for using a bucket is it is already curved, but you could use anything flat and use a Heat Gun to form it. You can get 4-5 bucket flaps and a dog dish out of one bucket. You can even put an upturned edge using a former ( 1/2" Breaker bar) and a heat gun.
Regards Martin.




Extended Length Mk2 version.

Prototype Upturned Edge Version

A satisfied customer here.  I have two 16Valve K100's with dollar store bucket mudguard extenders.  THey work great.

This is now on my bucket list.

That's a cool idea to use a pre-curved piece of plastic stock! I also like the idea of custom mud flap extenders since I live in a rain forest and there is usually debris on the wet roads. The extenders keep my engine front free from debris and may help to keep my shoes drier. Plus the custom ones cost less and can be tailored to my preference. The fanciest one I made was from stainless steel sheet metal, kind of a pain to cut curves in.

After trying various materials bolted through my fenders on a variety of bikes, and one or two failed purchases of extenda-fenders when I discovered they didn't fit my application after I received them, I went for another solution using 1/8" neoprene gasket material.

Like Martin, I also used a cardboard template I shaped and adjusted to my preference. After cutting the neoprene to the template, I fixed it to the fender using 3M Fast Tack Trim Adhesive (I've had it for a while and they may have a different name for the product now). The adhesive has proven durable and it doesn't commit me or anyone else to holes in my stock fenders. If anyone wants it removed some solvent can un-tack the adhesive.

Mikey D