seems like everytime someone posts a picture of their new cruiser, one of the first replies is, "those fenders will fall off, and you will flip over the bars..."
to me, fenders are what make up a cruiser. without them, there's just no style. plus, fenders keep dirty water and mud from splashing up on you and your engine.
so here's some tips that've worked for me since before i even thought of motorizing my bike:
first, the quality of the fender is a big part in keeping them, and you, alive. if you've got really cheap, flimsy fenders, the easiest thing to do is upgrade them to Wald fenders (Wald Bicycle Baskets, Training Wheels, Fenders, Racks, and Accessories - Fenders
.) these are available everywhere. they've been the most popular fender for a million years. they make almost every style and every size you could want. the chrome is awesome, and the mounting hardware is excellent. and you can buy struts, brackets, etc, seperately. they're about $30 a pair, or less.
regardless of what fenders you have, i'm gonna show you how to make them better.
if your fender struts are riveted on, drill those out. the older they get, the looser they get, and they'll eventually fail. especially the new, cheap aluminum rivets on dept.store bikes.
now that you have the fender struts off, slip some heat shrink tubing (usually 1/2" fits) on, and slide it up to the middle, and shrink it on there. (PIC 1) poke some holes for the bolts with a phillips screwdriver or something.
this gives you a rubberized, non-slip contact surface, and is probably the best tip for dampening the vibration.
replace the struts with some good bolts, washers, and nylock lock nuts. i use black,grade 8 button head allen bolts, just because they look cool. (PIC 2 you can see the heat shrink sticking out, and PIC 3)
for the center bracket in the front, my bike's old enough that it has a threaded, welded cap in the bottom of the fork, but your's probably has a cheap, flimsy "L" bracket. REPLACE THAT NOW. get a steel bracket from Lowes, or buy a Wald one, or make one, but whatever you do, make a strong one. this is the main cause for fender failures. that breaks, fender slides and jams up, you need new teeth.
replace that hardware too, and make it match, so it looks good.
now you can spray the underside of your fenders with rubberized undercoating, if you want. it's supposed to help with the vibes, but i've never done it, just because my fenders don't rattle anyway.
so, you're ready to mount them to your bike.
if your bike has a seperate hole in the rear drop-outs, i'd mount them there. some bikes have these holes, but still mount to the axles. i dunno why.
what's always bugged me about mounting fenders to the axles, is that the strut is so flimsy, it gets bent, chewed up, and there's a cheap piece of tin coming between the solid steel of my forks, and an axle nut. it just seems like a weak link to me. plus, old bikes like mine have strut rods (PIC 4) and having all this stuff held on by my axle nuts bugs me.
if your lucky, you have long enough axles, and you can do like i do (PIC 5.)
that should about cover it.
good hardware, no rivets, heatshrink, strong brackets, solid mounting.
my fenders don't move when i ride, and they're 70 years old.