[ST] Re: Chain Tension

[Neil Lindsey <neillindsey@xxxxxxx>]

original message:

>From: "William Sanders" <tuckersdad@xxxxxxxxx>
>Subject: [ST] Chain Tension

>Anyhow, much to my
>consternation, I found that my chain is grinding down the trailing end of
>the plastic chain guide/protector which is located on the top of the SS
>swingarm on my '01 ST.

>Only change I've made is to
>replace the countershaft sprocket with a 17t (Triumph brand) vs. the stock
>19t.

When you say trailing end of the plastic protector do you mean toward the
front of the bike.  Assuming that you don't have too much free play in your
chain, it is probably a direct result of the reduction in the size of your
countershaft sprocket.  Being of smaller diameter, the chain will now sit
closer to the protector at that end and can rub on it.  I was forewarned
about this by the Canadian Triumph rep and is one of the reasons I am opting
to increase the rear sprocket size instead.  The other reason to go with a
larger rear sprocket is that a smaller front sprocket will increase chain
wear somewhat, because the chain must turn a tighter corner around the front
sprocket than before.


>I check/adjust the chain with the bike on the centerstand. Is this the
>correct procedure? Or should I be checking it while it's weight is on it's
>wheels?

The procedure quoted in the service manual assumes that the bike is on the
centrestand.  Since the pivot point for the SS swingarm is NOT the same as
the centre of the front sprocket, the chain goes slack when the suspension
hangs.  It can also be done with the bike on the sidestand because the rear
suspension should not compress appreciably with no rider onboard.  The slack
CAN be checked while the rider sits on the bike but the free play should be
much less than the manual specifies (not sure how much however).  With the
rider sitting on the bike the centres of the countershaft sprocket, SS
swingarm pivot and the rear sprocket should be in approximate alignment
which means the chain will be it's tightest (ignoring uneven chain stretch
and the fact that the rear sprocket could even be mounted off centre a bit).

Neil



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