Mountain Biking - 2 speeds possible with single speed kit.

My friend is buying a single speed conversion kit for his bike and we were just wondering if it is possible to have the rear single speed but keep the front a dual chainring with a derailer. So he can only switch the fron gears. In a sence he would have 2 gears. Is this possible, Im thinking it is because he is buying a chain tensioner to use with it. Just want to make sure.

I don't know how well that would work.. if the chain's long enough to fit on the big ring, it might be kinda loose when it's on the small ring. Although maybe a tensioner would do just as good a job as a rear derraileur would.

Has he considered just a single ring setup?

Well ya he has considered it because it was his initial plan. Then we got thinking how cool it would be to have 2 up front. Either way he is going single speed in the rear but this would be better.

why?? does he want to go single speed or not? imo if he's going to go 2 he might as well go 5-6, i.e. go single on the front and just keep the rear derailer/cassette. if he's REALLY set on 2 gears, then i would also think that instead of doing 2 up front, use spacers and do 2 cogs in the rear, depending on how much he cares, might not even do a derailer in the back, just the tensioner, need to switch gears? stop and switch it over.

i dunno... i just think it'd look kinda goofy to have the extra ring and derailer up front when it's so simple in the back.

He would like it like that so he could have 1 gear for climbing and 1 gear for speed, its just that simple. If he had 2 gears in the back they wouldnt be that diverse of gear ratios. But if he had two up front they would be totally different. Plus, I dont know about you guys but we all feel the same when we say that front derailers are more reliable than rear. I just want to know if it will work. I guess we could always try for ourselves.

Won't work, chain line on a SS is the major key to having it work.

White industries makes something called the double double, two ratios without any difference in chain length, or a skewed chainline. Double freewheel in back, and double chainrings in front.

http://www.whiteind.com/ENO_web/eno-index.html

You still have to get off the bike to change gears though.

If he had 2 gears in the back they wouldnt be that diverse of gear ratios. But if he had two up front they would be totally different.

not necissarily, you could run a 12 and a 34 cog if you really wanted. the limiting factor of how diverse your gear ratio will be is the play in your tensioner. i don't know if you can have a 32 and 22 front chainring and have it be able to keep the chain tight for both, that would be a matter of inches in the chain. but i guess as you said, it might just be a matter of trial and error...

I just saw this, looks like it's similar to what he's trying to do - http://www.rivendellbicycles.com/html/101_quickbeam.html

But, I'd guess the horizontal dropouts make or break that feature.

set it up like a hirondelle :D

http://www.bikeforums.net/showthread.php?t=131632
(from the alt bike forum)