Chain Tension?

[Disco]

Ok, this is not your average question... i'm chasing some tech opinion.
I run a singlespeed RM Flow (73mm BB shell, vertical dropouts) with a 13-25 gearing, the 25t being on a Truativ Luftalarm Disc with 1/3 bashplate.
I also like to sprocket grind!

So the problem lies in the chain tension. I ran a new chain (KMC Gold) with a half link for the last few weeks, and the chain tension was slightly loose, but it wouldnt jump off. But now the chain has worn in, the tension is quite loose and i dont want the chain to fall off... well obvious reasons!

I have previously run a sprung tensioner and thrashed the hell out of it and my dropout, and a Rennen rollenlager too, but I'm not to game to mount things on my dropout hanger. I can't really run a bottom roller from a chainguide and swing it back for tension, because the smallest most chainguides go to is 32t and mounting on the BB shell would be dodgey, you cant really space out the 73mm shell like you can a 68 and just run a 73.

So this is where I stand. The only other solution (Other than new dropouts Grip style... cmon its a brand new frame!) Is mounting a tensioner along the bottom of the chainstay, sliding it along the horizontal axis to loose or gain tension, like those Ging style rollers... but they are made out of a pissy plastic side plate on each side of the roller and also are too long (ie sit lower than hight of the chainring) for grinds.

All i could think of is a home-made guide (proper) that slides along the chainstay and bolts into position.... with a roller like a fixed upside down U shape made out of chopping board style material that the chain would sit on.

Please lend me your ideas on how to do this... DECENTLY!

Michael
(If all else fails i spose i could run the rennen... but it's not preference)

 

[t]

make a bottom roller plate your self (or get Grip to do it) flows are bb mount so get a flat plate and drill a big hole for the BB and a small hole for an MRP roller at the appropriate distance apart.

 

[Disco]

Problem with that sits that the roller would interfere, as the chainring is so small. I also noted that because, unlike other chainguides that are designed around that system rely on a mech for tension, and hence dont need to be ajusted once the rollers are on. Otherwise it will be a Set BB, put everything together, check, reset and so forth till it is set. Really a lot of bother.
Otherwise that would have worked...

Michael

 

[Karnage]

mike, get the bottom roller on like t said but just get a 36T e13 to bash/grind on.

 

[Disco]

Justin, I've already got a bashplate! And being Luftalarms, they have a 1pce disc that cant mount it, also because it is too small!
Can anyone see my thaught process with the under-Chainstay one?

Michael

 

[bradh]

the rennens are pretty low-profile, so i would have thought that it would have been ok. i certainly would have suggested a rennen if it wasn't for the fact that you've got one already.

your ging-style chainstay-mounted tensioner idea sounds ok, but a roller would be better than teflon, so maybe it should push the chain down rather than pulling it up... that way it'd be low-profile but it would run nice and smooth.