I run the Sugino RDs and am having the chainline issue that comes along with them (45mm in front, 42 in rear). It's not horrible, but the bike's not silent like I would like it to be. I can't move the chainring to the inside of the spider, because it wouldn't clear the chainstays on my Rush. What I'm considering is throwing a spacer inside the cog to move it out an extra mm or 2. Will this mean certain death for me? or will there be enough threads left to ride safely?

my guess is that you could attempt that with SS but not with FG. but more than likely, replacing the BB would be the most ideal solution.

i wouldnt do it. youre losing both cog threads and lockring threads

Yeah I would find a shorter BB spindle...

Yeah do not do it.. a few extra mm on a chain line is not worth risking your safety. Go with a new BB if anything.

What kind of chain are you running? A dif. one might help the noise too. I use a SRAM 8 speed chain and it made a world of dif. compared to my izumi $8 chain that I initially had.

But if he puts in a shorter BB spindle to get the front chainline at 42mm that would put the chainring in the same position as using the inner position where it doesn't clear the chainstay.
What about a smaller chainring on the inner position and corresponding smaller cog?

Shorter spindle. Dimple the chainstay. Done.

get some competent advice from a mechanic who can see the situation with his own eyes...don't risk your safety by asking on the internet.

as a former pro wrench, i'd tell you that it is absolutely possible, depending on the thread depth on the hub.

i've had a 1mm spacer behind an EAI cog on a cane creek volos wheel for literally thousands of miles. *BUT*, with the spacer in place there are still plenty of threads for both the cog and the lockring to engage.

YMMV.

What i do is run a 1/8th inch chain with a 3/32 ring and cog, lube it properly and i'll i hear is the wind in my spokes

Sugino RD's give a 45mm chainline with a 103 bb. The only options that I know of that come any smaller would be an expensive Campy bb or even more expensive Phil bb. You can get a 107 bb and put the chainring on the inside of the spider (longer bb would give you enough clearance for that) or just get a cog that pushes out from the shoulder more (like an EAI) and live with an imperfect chainline. Having 1-2 mm of difference in your chainline isn't going to kill your drive train.

terrible idea, kid brought a wheel into the bike shop today and whoever had it before him had spaced the freewheel with the same idea. the freewheel stripped out all the threads not covered by the spacer.