Chain tensioner with cassette
 

Building up a new MTB and I stripped the drivetrain off my old bike and put it on the new and decided to build up the old as a SS foul weather bike. I was going to just toss on the performance bike single speed kit (http://www.performancebike.com/shop/...slisearch=true), but got to thinking: If I kept my old cassette on and put a chain tensioner on would I then be able to have a manual 8 speed?

The only problem I can think of would be the chain tensioner needs to be properly aligned but then again I've never used a tensioner I figured it was just like a rear derailleur sans shift springs et al.

Uh... what exactly do you mean by "manual" all shifting is manual... as in the rider has to do it manually. Except for those fancy electronic prototypes. Or that crazy bike on late night tv.

The chain tensioner is designed for a frame that has vertical dropouts. Because you are unable to adjust the rear wheel position and thus unable to properly tension the chain... you would need to use that device.

If you are going to keep an 8 speed cassette on and you are saying that you would want to use the tensioner so that you could keep the chain way long and make it usefull in all 8 gears (as opposed to switching a cog everytime you wanted a different gear ratio) this is what the derailler was invented for.

I mean... you could do it... but why?

No. You need some way to line the chain up with the cog you want (it's not going to just stay there) and you need a way to take up the extra chain when you go to a smaller cog. You could use an actual derailleur with something to hold it in position - like a shifter. - TF

Thanks. I figured it had something to do with the chain line. I guess now I need to get unlazy and take the cassette off.

it works i did it for a wile. as long as the tensioner aligns your chain with your cog before it rolls on to the cog your fine if it not perfect it will want to jump up to the next cog though.... Id go with the single speed kit. As im sur eyou know the cheaper way to do things is always more ghetto than doint it the right way for 20 bucks more