Swing arm travel

[bswinn]

Alright gentleman, and ladies if they're there, I have a question for you all.

Last night I looked at how I had my rear fender mounted to my bike. It's currently mounted to the swing arm with minimal clearance to the tire. Was a little concerned about this and the vibes of road travel shaking the fiberglass apart so I toyed with the idea of mounting the fender to the frame.

If it's hard mounted to the frame I need to make sure there is enough tire clearance for travel. I busted out the old Trig book and used the law of Cosines to figure to total up/down travel if the shocks did a FULL compression. Turns out if I did my math correct a full compression of 2.5" on the 11.5" MikesXS shocks would result in a 4" vertical travel of the rear tire. This could be a problem. My fender can only make a max clearance of 2.5"

Would this be a problem? Or if my shocks did a full compression would I be in a whole world of hurt and the fender and tire are the least of my worries?

First picture attached is how the fender is mounted but with the stock shocks. Second picture is a photo of the new cheapo shocks from Mikes.

 

[jd750ace]

If you don't relish the thought of your fender getting busted off, keep it mounted to the swingarm. If the fiberglass is worth 2 shits, and you put a thin rubber isolation washer on it where it ties in to your struts, it should be fine. If the fender is chop, I would be concerned. If it's full weave cloth, and was laid right (3 way bias) it should be pretty solid.
Since it's you own mash-up, you won't know if it's too close to the tire for road vibrations and such until it hits. Welcome to Cussed Em fabrication.

3-way Bias:

All woven fabric has a warp and fill direction. It's the manufacturing direction of the cloth. There is the side that is the straight runs over the spools of the machine, that are tight all the time during manufacturing, or the Warp, and the strands that are laid in laterally across, known as the fill. Typical fiberglass cloth layup practice is to rotate the cloth 90 degrees to the first layer, when laying the second, then the third is laid at 45 degrees to both, giving the most omnidirectional strength the material is capable of. This continues if you have successive layers. Odds are, if that fender was less than 150 bucks, nobody cared that much.
Just my $0.02, but even if they did not orient the strands as such, full weave is always more durable than a chop gun job.