Slack point in chain - How much is too much

Hi all.

I have a question about my chain on my fixie which a friend recently put together for me. (I am a first time fixed gear rider and am not used to horizontal dropouts).

If I adjust the chain so that at the tightest point it is tight, but not so tight that it causes the drive-train/bearings to bind, then at its slackest point there is very noticeable droop in the chain. There is about 1-1.5cm movement from centre if I push on it, where as at the tightest point of the cranks rotation there is almost no deviation when i push up or down on the chain. i can feel it when braking and am wondering if the cranks or BB are out of shape enough that they need to be replaced.

How much difference between the tight and slack points of the chain should I expect?

Thanks in advance for help.

A little or alot. It all depends on how round your chainrings and cogs are. Although it doesn’t look like it, most chainrings are NOT perfectly round. What you are experiencing is normal. There are ways to make the slack less. Do a search on Sheldon Brown … he’s got a method there which I can’t be bothered to find now.


rotate, hit, repeat. well… sortof. :slight_smile:

Yeah I tried the Sheldon Brown method, but I either aren’t doing it right or something else because it didn’t make any difference. The chain ring is tight around the crank spider (as in there is no way it can move the the position it is currently in) so I didn’t see how it would make a difference.

It is recomended to have about 1/2 an inch of slack in the chain at the centerpoint between chainring and cog. So the 1 to 1.5cm you speak off sounds OK. As long as the chain is not loose enough for it to come off the chainring/cog, you can ride your bike safely.

I have never had a uniform chain tension on any of my fixed gear bikes (7 to date). Just live with it.