If installed according to the directions it would contact either the tire or the belt. The guard is an excellent idea but it takes a time consuming custom install to get it right. The 90 degree bend it comes with is off just enough that it will not accommodate my bike.
This is exactly what happened to me. I managed to worry myself sick about getting a rock on my drive belt and hence ordered the guard. I regretted the experience. Theoretically it is a good idea but my experience was not good. You have to install the thing so that the bottom is centered between the tire and the belt. You have no more than 1/4" or 3/8" of an inch in which you have to center the guard. In 20-20 hindsight, this may not be that difficult if you have the Spyder on a lift where you can get directly under it and therefore ensure that it's perfectly centered. The instructions don't say that's necessary and I tried to do the job using a ramp to get the rear end of the Spyder up in the air. The installation seemed to go okay. I had dry-fit my guard perfectly but when I installed it, it was off just enough that the guard managed to touch the belt.
Regardless, once I had it installed, that was it. You're not supposed to heat the plastic to bend it but that's a moot point because once it's on, good luck trying to get a heat source up inside those close quarters. Without heat, I was unable to bend the plastic at all; you have little ability to even move it once it's installed (remember, it fits into a 1/4" to 3/8" opening) and it simply springs right back. Next, I tried cutting part of it away at the bottom with my Dremel but was unable to cut enough of it that it wasn't still touching the belt. I considered ignoring the issue and opted to ride around the block a couple of times as an experiment. When I stopped, I found fresh rubber dust on the guard. The only possible source of the dust was the belt. At that point I had spent several hours trying to make this thing work and it just wouldn't. The guard had to come out and in the process it was ruined for reinstallation (it wouldn't really have mattered because it was already ruined by me cutting it back with the Dremel).
My problem was rubbing against the belt. They say it's okay if it's rubbing against the tire. I don't agree. It may be fine for a long time but if it's rubbing, something is going to wear away. Hmmm, which will wear faster, the rubber tire or the hard plastic guard? I say it's going to be the tire that suffers. Eventually the guard would damage the tire and the day it wears through, that tire is going to blow.
After this experience, I debated whether to order another guard and try again. I wasn't sure I could ever get the thing centered and so I was already hesitant. I then wondered whether there was any real need for the guard anyway. You can find a few examples of rock damage here on this forum, but out of this forum, how many have actually had this problem? Seems like not really that many. Then I reasoned that there are a hundred times more Harley-Davidsons than Spyders, and they all have drive belts like we do. If rocks are a problem getting into Spyder belts, you would a hundred times more reports of Harley riders with rocks in the belt and perhaps some kind of guard like the Spyderpops guard to fit Harleys. According to my Google search, I found almost no reports of rock damage to Harley belts and nobody is making an aftermarket Harley rock guard. Either Harleys are much better designed than our Spyders or the extent of the problem is greatly exaggerated. I opted not to put the guard back on and just stay off gravel. I wished I had done my research before spending several hours on this fruitless project.
Note, I do not say the guard is a bad product. Certainly it couldn't hurt if you can get it installed perfectly. As I said, this may be possible if the Spyder is up in the air and you can access the installation from below where you can better see to center it. Otherwise I would never recommend trying to install this thing.
