So I have a frame that is spaced to 120mm...would I be damaging my frame if I used my MKS chain tugs with the washer on the "inside" of the trackend? The washer part of the tug is roughly 1mm thick I suppose so really I guess I am "stretching" my frame to 122mm. (the net effect is that I'm sticking a 122mm spaced hub into a 120mm frame) Is this bad? I'm kinda undecided if the 2mm stretch would do anything. I dont want to run them on the outside of the dropouts though because then the tracknuts aren't "secured" and the serrated edge isn't touching anything, just kinda floating since the washer is smaller than the diameter of the tracknut.

No you would not.

2mm is about the thickness of a standard house key, it won't make a difference.

-Chris

I run mine on the inside and so does my buddy. We've had no problems. We also have steel frames though.

Not a problem to do so, I'm sure, but why are you worried that your track nuts aren't "biting" into drops? They don't need to do so as they are secured by the tensioners...

What about chain slack and the non-drive side?

not really that I'm "concerned" with my nuts not biting the dropout...It's really hard to explain...I guess you need to have the MKS tugs to understand...the serrated portion of the nut sits at an angle to the dropout and never makes contact with the dropout because the washer on the chain tug kinda, half assedly fits "inside" the serrated part of the nut. Thanks for all the replies too guys..I guess I'll leave it the way it is for now.