Aux Rear Flasher Hanger
My bike bag on my rear rack obscures the flasher on my seat post. I still have one on my rear bike rack, but I use two flashers. To solve the problem I used a stiff piece of plastic from a cheap notebook cover to create a loop of plastic across the rear fender. If you do not have fenders this method will not work for you. In USA hardly anyone has fenders on their bikes. In Europe hardly anyone does not have fenders on their bikes. Guess who is more comfortable in the rain and keeps their chain and chain ring cleaner? This only works with the SKS fenders. The Zefel fenders do not have the bolts to hold the plastic secure. Obviously if you have no fenders, this will not work, but if you tour or commute chances are that you will have fenders. I recommend the SKS brand, although I have both types on my bikes.
The nut seen in the photo is the one holding the fender stay to the fender. There is one on each side. The plastic is drilled and installed just as you would use a washer under the nut. The blue plastic has a couple of turns of friction tape where the light clips on, too keep the light from slipping to the side. This photo also shows the SOLAS white reflector tape on the rear fender.