Chain Geometry

[Zulu]

Originally Posted by oldndumb

It isn't exactly rocket science is it, considering you are dealing with two different radii?

What other result could there be?

The illustration is not about 2 radii but more about the relative position of the rear sprocket (moving in an arc around the fixed swing arm pivot) to the fixed front sprocket.

[oldndumb]

Call it what you want, but you just described an arrangement of two radii of different lengths.
chainslack.gif

Swing arm down, chain tightens.
Swing arm horizontal, chain remains at pre-set slack.
Swing arm up, chain tightens.

That is why the folks at T describe the chain adjust procedure. The recommended slack is derived from the swing arm geometry to prevent excessive chain tension. It is also why it is best to avoid the low range of the spec and adjust slack to the max range.

[Zulu]

Originally Posted by oldndumb

Call it what you want, but you just described an arrangement of two radii of different lengths.
Attachment 5949

Swing arm down, chain tightens.
Swing arm horizontal, chain remains at pre-set slack.
Swing arm up, chain tightens.

That is why the folks at T describe the chain adjust procedure. The recommended slack is derived from the swing arm geometry to prevent excessive chain tension. It is also why it is best to avoid the low range of the spec and adjust slack to the max range.

Please take another look at the PDF file attached to my original post. It shows the chain becoming slack as the swing arm move up or down.

[TriplePete]

Originally Posted by Zulu

Please take another look at the PDF file attached to my original post. It shows the chain becoming slack as the swing arm move up or down.

OK. I am no expert on motorcycle chain tension, but your drawing is geometrically correct if you are calculating the from center axis to center axis.

From what I have seen and experienced, most bikers adjust their chains according to lower slack. That lower slack will change according to suspension position, BUT also to upper slack. Put the bike in gear and roll bike back and forth and you'll notice the slack change from bottom and top.

Now considering those factors - the lower slack will tighten when suspension is compressed and the upper slack will be reduced and vice versa. So I guess my question is - where do you start when checking chain tension?

I also would like to know how to adjust SSSA chains as my 2K6 Sprint is my first with SSSA.

Thanks

[oldndumb]

Is there any reason that you would not want to follow the owners manual instructions?

[Calliway]

Wow,
I just read all the way thourhg this thread finally. It didn't have a ton of interest to begin with but who new chain tension could become so, well, complicated. I just follow the directions in the manual and stick to the "slacker" side of recomendations. Good discussion but really Triumph has put forward the proper way in the owners manual.

Enjoyed the read.

[oldndumb]

I think it is only complicated for the Nintendo racer crowd.

[TriplePete]

Originally Posted by oldndumb

Is there any reason that you would not want to follow the owners manual instructions?

I wish I had an owners manual and OEM tools.

[TattooedRedHead]

OnD lay off Yoda man...

I didn't understand any of this geometry before tonight...

I thought the chain would get tighter with compression not looser.

Then again, I did BARELY pass geometry in H.S. with a C-

I'm a great pool player too, and my dad always bitches to me, Son... it's just geometry... I reply... yea remember how well I did in my geometry class? Ok then.

Thank you original poster for the informative drawing, you have clean dimensioning I have a drafting background, and that is one clean plan.

May I ask if it was created in Autodesk AutoCAD or some other lesser evil?

--Kory

[oldndumb]

Kory...Get up to speed, man. I've already laid off Yoda man. No debate there at all. OMG, interpersonal relationship advice from Kory.

TriplePete...You never stated that you do not have an owners manual. They are available for purchase from several online sources.

There are also many threads on chain adjustment, unless you are one of those search adverse people. I would do it for you, but ........