Chain tension

[slowflyn]

So this is driving me crazy. Long ago and far away chains were to to kept tight to avoid them throwing and doing unpleasant things. So I usually keep mine at manufactuers recommendation. Well at the track they want it very loose and sloppy. The tech tells me how the universe has changed and blah blah blah. So do you set your chain tension one way for the track and another for the street?

[Anonymous]

Hmmm, I didn't know that??? Well, I've never been to the track...

[The CyberPoet]

What to know:

A tight chain is less likely to jump, but will both bind the suspension movement some and is far more likely to snap (break) unexpectedly. Plus it wears much more highly on the chain. These factors are exagerated during track riding because of the higher-than-typical-road-level driving done.

A loose chain is more likely to jump a tooth if it's in poor shape, but far less likely to break, and during a typical trackday, it isn't as likely to break unexpectedly (thus reducing the odds of you going down, and taking other riders with you, and/or contaminating the track).

The factory spec is 1" (+/- .2") of slop (1/2" up plus 1/2" down) with the rear wheel hanging off the ground on the centerstand (i.e. - with the rear suspension at max extension). I recommend using 1.0 to 1.1" as ideal in this set-up... Tighter and the chain will stretch prematurely; looser and it's more apt to jump.

Cheers
=-= The CyberPoet

[Spedee]

So a rear bike stand is going to give a improper reading?

[slowflyn]

Thanks Cyberpoet, you are the Kats meow.

[The CyberPoet]

So a rear bike stand is going to give a improper reading?

I recall going through trying to figure this out when we were all still at KP -- whether the max distance on the chain was with the swingarm fully deflected downward, or with it straight back (given that the swing arm pivot and the front sprocket are not in the same spot, you end up with a triangle to think about). I can't remember the conclusion off the top of my head, so let's work through it again...

The swingarm's motion forms an arc from it's pivot.
The chain's possible positions also forms an arc...
Thinking about it, the tightest it should be is with the swing arm perfectly inline between the front and rear sprockets, and the loosest would be with the swing arm hanging down. Now you just have to figure out how much difference in slack that actually represents (1/10th - 2/10ths of an inch?)... I can probably figure it out later after I've finished my other tasks for the day. Just measure the chain slack on the centerstand (wheel hanging down) and again on the sidestand (wheel supporting the bike) and you should have the difference.

Cheers
=-= The CyberPoet

[Spedee]

Thanks CyberPoet. Something for me to look into.