I have worked a deal to trade my stock Hebo bars for a "custom" made Shark fin for the rear rotor. The guy will fabricate one for me out of aluminum. My question is this. There are two holes on the bottom side of the brake caliper?, I am afraid that mounting the fin here will transfer all of the shock of a hit to the brake casting. The holes are threaded and are obviously made for something to be mounted here. Any ideas or suggestions would be appreciated.
The two mounting bosses are plenty strong for the shark fin. The only alternative is to get a billet caliper mount like Scotts' sells. Make sure the mounting bolt heads don't potrude past the swing arm, they may hit when you adjust the chain.
A sharkfin from a late model KTM w/ Bermbo caliper will bolt on to your GasGas. The 2 threaded hole are for a disk guard. You can buy them pretty cheap. No worries about it being bolted to your calpier and causing damage. On my last bike, mine was welded to my caliper and that thing took much abuse from that desert!
My advise to you is, have it welded to the caliper, it will be much stronger, and will resist breaking off your threaded taps.
Bolt it on, and then have it welded with a good bead on both sides. I snapped off the carrier mounting tabs with every bolt on fin I've had. With it welded, the fin just gets tweaked a little now and then, doesn't hurt the carrier, and is eaisly straightened.