coyotecrust

ok so i learned to center the chainring on the crank spider of a fixed gear but i am wondering how important it is to have chainrings centered when yr building a crankset for a bike with a rear derailleur. probably not too important because the tension is kept by the derailler so it doesnt have to be perfect?

i may have just answered my own question.

sydney

Chainline is still important. There is more to it than chain tension, and why every crank has a spindle length spec.

2manybikes

You did......you were right.

San Rensho 

Chainline is very important. The chainrings (I am assuming 2) should line up so that the center cog in the freewheel/cassette (with odd no of teeth) lines up right between the two chainrings. With even no. of cogs, you essentially have 2 center cogs, each one should line up with a chainring.

supcom

Yes, you answered your own question. Any minor deviation from center will be handled by the rear derailleur cage and will be unnoticed.