Checking chainline

Josh Hassol said:

Hi, all -

My bike has a single chainring, and a 9-speed cassette. What's a
simple way to check the chainline? Thanks.

Take a straightedge and lay it against the chainring, long enough to reach
back to the cassette. It should line up to the same side of the middle
sprocket on the cassette.

I bet you're asking since the chain tends to drop off the chainring. That
is a weakness of having only one chainring. The front derailleur helps
hold the chain on the chainring.

If you don't want to put on a derailleur, you might look at a chain
watcher (if it just drops off to the inside). Another option would be a
bash ring (a larger-diameter disk outside of, or on both sides of, the
chainring, to protect it from rocks and/or to protect your pantsleg from
the chain). Those are often used on cross bikes that only have one ring.

--

David L. Johnson

__o | "Business!" cried the Ghost. "Mankind was my business. The
_`\(,_ | common welfare was my business; charity, mercy, forbearance,
(_)/ (_) | and benevolence, were, all, my business. The dealings of my
trade were but a drop of water in the comprehensive ocean of my
business!" --Dickens, "A Christmas Carol"

David L. Johnson said:

Josh Hassol said:

I bet you're asking since the chain tends to drop off the chainring. That

is a weakness of having only one chainring. The front derailleur helps
hold the chain on the chainring.

Thanks for the tip. Actually, I've never had a chain drop! I guess I have the chain at just the right length.

Josh Hassol said:

Hi, all -

My bike has a single chainring, and a 9-speed cassette. What's a
simple way to check the chainline? Thanks.

Josh

The chain, when on the ring and middle cog, ideally would be parallel
to the top tube.