Originally Posted by
wildwildebeest
Hello
I'm thinking of building a singlespeed bike. I have a frame with vertical dropouts and was hoping to get a flip-flop hub with one side fixed and one a freewheel. I've heard that you can tension the chain enough simply by sensibly choosing the cog sizes and by removing links or half-links from the chain... is this really true?
What you're aiming at is called "magic ratio", a certain size of chainring + sprocket that will have your chain as tensioned as possible. Fact: magic ratios suck the big one. Even with a half-link. It's enough for the chain to elongate even a tiny little bit, and your chain will be too slack.
Magic ratios only work if you are ready to shell out for a new chain every 1000 Km.
The other bid effing disadvantage is that you are not free to chose your gearing - you are limited by the magic ratio options, which sometimes are equal to only one, and that one might be way too high or way too low.