Chain and Cable Slack

[keithaba]

When measuring chain slack or cable slack, does the spec refer to the entire range of motion (up and down), or just in one direction?

For example, look at this picture.

It indicates that you should have 1.57 - 1.97 inches in 1 direction (up). 1.57-1.97 is what the manual says chain slack should be adjusted to.

So if the chain moved 1.57 inches up, and 1.57 inhes down, is that in spec, or too loose? (total play is 3.14")

I've read how to's that indicate both so I'm wondering which way is correct since this is pretty important to the chain and other cable's that I have to measure slack with on the FZ1.

 

[Silent]

I've always measured mine full travel at the center of the chain. I don't recall what my Ninja's specs are atm. The slack is there so the chain doesn't bind as the suspension moves up and down. 3" of travel doesn't seem extreme to me. Most people tend to run there chains to tight.

YMMV

 

[keithaba]

I've always measured mine full travel at the center of the chain. I don't recall what my Ninja's specs are atm. The slack is there so the chain doesn't bind as the suspension moves up and down. 3" of travel doesn't seem extreme to me. Most people tend to run there chains to tight.
YMMV

Here is a picture of how I measure chain slack, which sounds like what you were describing. Also what I thought to be correct.

On the FZ1, you measure chain slack on the center stand because when the rear tire is on the ground it tightens the chain because of how the swingarm is designed.

The only explanation I could see is that in the picture on my previous post, you can't see the persons hand, and he is pushing the chain down as low as it will go.

 

[Fred W]

Seems we are all in agreement. The slack is measured peak to peak.

How else would you do it? Use a straight edge? Too much work...

 

[Randy]

First off, make sure your rear suspension sag is set correctly. Then, from the chain hanging freely, press up and measure the distance. It's important to do this in 3 or 4 different spots as the chain does not stretch equally across all of the links.

 

[Warchild]

Interestingly, the Blackbird Owner's Manual says measure the slack on the sidestand; the Service Manual says to use the centerstand. :blink:

It apparently doesn't matter for the XX, but I have always done it on the centerstand, so you can easily rotate the tire to check for tight/loose sections of the chain.

And, yes, you measure peak-to-peak.... I was taught to use the roller pins as the measuring point. Typically, 30mm of slack is indicated, and this slack measurement is taken at a point in the chain exactly halfway from sprocket-to-sprocket.

 

[Geezer]

Hmmm, I always measure chain slack with both wheels on the ground and someone on the seat to compress the rear suspension such that the swingarm is about horizontal. That is the point were the chain is at it tightest on any bike I've owned. You can find the right point by watching the chain tighten as the suspension compresses and then loosen again if the swingarm goes past horizontal. At that point I usually try for about one inch of slack.

 

[Fencer]

Keith,

For track stuff, I have been tod by folks at the track to run the chain a little more loose than norm, and you def don't want it too tight on the track.

PM Andre, he should be able to give you good insight.

 

[charismaticmegafauna]

Hmmm, I always measure chain slack with both wheels on the ground and someone on the seat to compress the rear suspension such that the swingarm is about horizontal. That is the point were the chain is at it tightest on any bike I've owned. You can find the right point by watching the chain tighten as the suspension compresses and then loosen again if the swingarm goes past horizontal. At that point I usually try for about one inch of slack.

You're right on-target, 'Geezer'. Although, given the pivot-point of the chain arc (front sprocket) and pivot-point of the swing-arm -- it might be something other than horizontal (where that 'longest point' occurs)? That 'longest point' is where the two arcs intersect. I wish I could draw here -- I'd add a diagram.....

Anyway -- most manuals, I think, try to simplify all this. Mainly, I think, because most don't want to do it at all (let alone go through the process of doing it correctly)....? The 'process' is an attempt to make some acceptable good out of a glaringly inadequate design -- i.e., open chain drive....(imo).

'Silent': Most people tend to run there chains to tight.

Agreed -- better loose than too tight. My recco: when adjusting, err on the loose side. :blink: