I'm intrigued by chain tensioners, and I'm considering them on my Mark V. However. I've gathered that NJS frames are spaced to accomodate the use of chain tensioners. Can one use chain tensioners on frames that do not have specific NJS rear dropout spacing? Are there any detrimental effects from using chain tensioners?

yea you can still use them. if your drop outs are too wide MKS makes some beefier ones (i think 9mm).. If those still don't fit, you can dremel off a side. Theres also more "techy" looking ones that would work. Only downside I can think of to using chain tensioners is it takes longer to get your wheel off when you need to change a flat.

go with the generic ones:
http://businesscycles.com/trtool_chaintugs.htm
for $7.50 (I have used one on my non-Japanese frames and it fits fine)

The time spent removing these tugs is negligible at best. Just keep a set of mini-pliers or a box-wrench that fits on-hand for easy removale

You don't have to worry about the extra 3 mm spacing that many keirin frames now put into their rear spacing to accommodate tugs. Just let the flat part of the tug sit on the outside, directly under the track nut. It isn't quite as non-slippable as having that part on the inside, but you'd only see the difference in UCI-level sprinting or kilo.

That being said, the easier solution is to spread the stay ends a hair. You can do it with your bare hands on most bikes (try it in very small increments because you'd be surprised how much you can over-spread it). If you can't budget it that way, grab a car tire jack and use it instead. Jack it open just a bit and leave it for an hour. You'll find the metal retains a bit of a memory of its new position. Again, work in small doses.

so how hard does one tighten the axle nuts? i guess i'm sort of confused about how *exactly* these things work.

sheldon brown says "Note! Chain tensioners cannot be used with fixed-gear or coaster brake systems!

They don't maintain tension when there is backward force applied to the pedals, and the chain can derail as a result."

ther are two type of devices that fall into the category of chain tensioners:
1. ones that secure the rear axle in place
2. ones that act on the chain itself, applying pressure of some sort to take the slack out of the chain (like a derailleur - surly's tensioner is a good example of this)

this post is about category 1.

it seems to me that one could first use the chain tensioners to acheive proper tension and then tighten down the axle nuts to keep that tension.

...but then again i'm not sure of that, that's why i posted the thread.

yes, I am aware of that. I was clarifying this for crayonsemble

Thats what I always have used mine for.....that was the only logical way to use it I figured

Wow! Thats all hardware store items.
you can make those chaintugs yourself for about 3 bucks.

http://businesscycles.com/graphics/tools_chaintug.jpg

maybe that's why they sell those for $3 here in Japan...

...and $1.25 here in Canada.