Rivet in Swingarm
 

I am going to fit a chain guard to the SV, is it ok to drill two holes on the underside of the swing arm to then rivit the guard in place.

If you're referring to the guard that goes in front of the rear sprocket, you won't have any choice but to drill fixing holes, although you should know that obviously it's not a good move, generally speaking, to drill holes in chassis or suspension parts.

I was thinking that. Any other way to fit it?

As I assume that it's basically an 'L' shape with the short side against the bottom of the swingarm, and two fixing holes, then no, can't think how else you'd fit it.

be very cautious about drilling a stress bearing component, and that goes double for aluminium.

Think carefully where the greatest stresses are going to be, and avoid areas which are primarily in tension and which see varying stresses (which unfortunately a swingarm does). This is what leads to fatigue cracking, and it's a function of the combined average tensile stress and the amplitude of the additional cyclic stress.

Unfortunately, unlike steel, aluminium doesn't have a "safe" stress level which will give infinite life, it's a question of when rather than if. Holes cause stress concentration factors which could reduce the fatigue life by an order of magnitude (x10).

The way the suspension works means that the stresses are greatest towards the front end nearest the pivot, and it'll be primarily tensile on the underside of the legs and primarily compressive along the top.

If you consider the swingarm legs as rectangular tubes basically in bending, there will be a neutral axis (where there is neither tensile nor compressive stress) running along the centreline of each side face. This would be the "least worst" place to drill.

If you can clinically prepare the surfaces, then bonding with epoxy is a viable alternative, but you do need to be scrupulous about the prep. A good way is to degrease the surface, mix the epoxy, roughen it with clean (i.e. unused) coarse abrasive paper and immediately (within seconds) apply the epoxy before it has a chance to oxidise.

If you do bond it, try to arrange it so the bond is in shear and avoid "peeling" loads if at all possible. Bonding on 2 planes (e.g. "L" shape bracket bonded on both faces to a square tube) is ideal if practical.

HTH :?

Bracket right around the swingarm would do it... Those sharks-fins are just to stop your foot going into the sprocket, really, so it won't need to deal with huge forces. So a c-shaped steel bracket? Hang the sharks fin off the bottom... You could combine that with Serious Epoxying a la Embee.

IIRC the R&G ones require 2xM6x10mm holes- obviously this introduces a weakness but I'd seriously doubt it's going to take you near critical weaknesses on a productionbike's swingarm... Bt would I count on it?

I wouldnt drill or weld anything mate, I saw a truck chassis break in half because someone had bolted a tool box on the side by drilling 4 x 10mm holes :shock:

I would ask Mike1234 what they use on the minitwins, although he will probably suggest drilling a couple of holes in the swingarm :P

Probably space age technology will help, like glue, or epoxy resin as suggested