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View Full Version : Adjusted chain tension - is this right



RantyDave
10th October 2006, 21:26
My chain tension had been bothering me. It appeared too slack, enough to be able to whack the swing arm and probably a contributor to low speed stuttering problems.

I fixed this by:
* Loosening the bolt that holds the wheel on.
* Moving the slider back a little bit, leaving a little slack in the chain.
* Making sure the wheel was square (showing the same number of divots on both sides)
* Bolting it all back together again.

It sure seemed a big PITA for something that should be quite simple though, and I was concerned about re-tightening the 'holds the wheel on' bolt since I didn't have anything to measure torque with. Or, indeed, any idea how tight it should be. Would it have been OK/possible to move it without mucking around with this wheel nut or was what I did the only real way?

BTW, big ups to paddock stands (thanks swanman).

Dave

Uncle B
10th October 2006, 21:52
Should be about 25mm of slack in the chain after tightening rear axle nut. IMO: it's better to run a slightly slack chain than a tight one as a tight chain put an enormous amount of strain on bearings.
Do not trust the marks on the swingarm as they will only be a rough indication....one way to check if your wheels are running true is the 'stringline' method.
Invest in a torque wrench. Ask any Triumph dealer how tight the rear axle nut needs to be.

98tls
10th October 2006, 21:56
In the bottom center of chain you should have about 25-35mm of up/down movement.........be careful when doing axle nut up as if your bike is the same as mine chain will tighten as axle nut is done up......so allow for that.

Ixion
10th October 2006, 22:23
Important gotcha : needs to be 25 - 35 mm free play, as stated AT THE TIGHTEST POINT OF THE SWING ARM MOVEMENT.

The chain may tighten and slacken as the swingarm moves up and down. If you don't set it for the tightest part it may be too tight which is a Bad Thing.

Push down on the rear suspension and check at a few points. (some folk are lazy and use a tie down to strap the rear down )

RantyDave
11th October 2006, 06:33
Thanks, will remeasure with some load on the rear suspension (although how 'er indoors is going to take being referred to as "load" is yet to be seen). I did already have fun with the "after tightening rear axle nut" gotcha and ended up undoing it all again and moving forwards a mill or two. God, sensitive isn't it?

I take it the stringline method is running a string from the shock to the back of the tyre to see if it's straight? I'll be pissed if the calibration marks are off, but not entirely surprised.

Dave

Blackbird
11th October 2006, 08:05
You're right not to entirely trust your calibration marks. A string line is fine but a bit of a pain in the longer term. Have a look at this thread and the PDF on how to build a laser alignment tool - only costs a few bucks.
http://www.kiwibiker.co.nz/forums/showthread.php?t=524&highlight=alignment