hello,
I am converting an old road bicycle i have to a single speed. FYI i know this is probally a dumb question but i am a novice mechanic and a noob to SS. so heres the dilema:
i am confused what the need for a chain tensioner is. can i not just shorten the chain to the correct length with my chain tool?
I know i am probally wrong but this question has been bugging me for a while.
I can provide any info on the bicycle as needed.

any help would be appreciated and thank you all in advance.

You'd only need a a tensioner if your bike has short vertical dropouts and chain tension can't be adjusted by simply sliding the wheel back as with horizontal dropouts.

A chain tensioner is only needed if you have no way to adjust chain tension by moving the wheel (vertical dropouts). If you have an old road bike with semi horizontal dropouts you should have no problem shortening your chain and using the available space in the dropout to get the chain tight.

edit: beat me to it

ok i believe i understand. so i would just need to move the axel further back to make tension once i shorten my chain?
the bicycle is a univega custom maxima. it is from the early 80's.
are these the correct droputs for what you stated?

Yeah, those dropouts should give you enough room to adjust your tension after shortening your chain.

ok thank you very much. I have an older mountain bicycle that i would want to switch to single speed also and it has similar dropouts. thank you for all of the help.
If i have anymore questions with my conversion i will just use this thread.

No prob. You may find this useful too:

https://www.sheldonbrown.com/fixed-conversion.html

thank you i have been using that site often but sometimes get confused with the wording and whatnot.

ok thank you. i just was confused becouse of all the talk with tensioners. i just didnt understand. but thank you it turns out i got lucky and didnt need a tensioner.

I know what you mean that usually is a sign that you have a bike with very short semi-horizontal dropouts.