[ST] RE: sprocket and chain

["Keith Tynan" <keith@xxxxxxxxxxxxxxx>]

> Date: Mon, 30 Sep 2002 15:39:43 -0400 (EDT)
> From: Bil Swartz <bil@xxxxxxxxxx>
> ...
> Which brings me back to RFC on what folks are
> setting their chain's free play to, how rubbing strips were doing,
> etc.  No replies thus far...

Bil,

One of these days (cabin fever time approaches) I'll get round to adding my
thesis on the final drive system to my web page, but for now, just a
summary...

Manufacturers (Regina & DID) quote 15 mm total freeplay with all centres
aligned. I've done the maths and can show that this translates to 40.1mm
with the rear suspension fully extended (i.e. bike on centrestand), hence
the quoted 35-45mm range.

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>
> Date: Mon, 30 Sep 2002 21:55:03 -0400
> From: Connie M Walter <labkelly@xxxxxxxx>
> ...
> Another thing I wanted to note is that I just got around to changing my
> chain out for a ZVM and thought I had a tight spot with the old chain.  I
> have ALWAYS been a little anal about keeping my chain lubed but I bought
> this as a used bike with 2500 miles on it.  Well as it turns out the
> tight spot which is pretty tight seems to be the result of an out of
> round rear sprocket.  When I marked the rear sprocket at the tight spot
> sure enough every time the chain is tight, the sprocket mark is in the
> same spot

Ken,

Beware!

More likely than the sprocket being machined out of round is that the
sprocket is mounted on the hub eccentrically. I have had severe problems
with this when  my ST was new, and I left everything to the dealer (2 new
chains in 1500 miles!!). No problems since I took everything into my own
hands. My current AFAM alloy sprocket is 0.4mm larger than the hub, so they
need to be centred accurately.

Another observation is that whilst the method you describe for this symptom
might work with a brand new chain, it won't work once the wear pattern has
bedded in, as the tightspots will occur at the lowest common multiple of the
sprocket and chain sizes.

Regards,
- --
BRG
mailto:keith.tynan@xxxxxxxxxxxxx
http://myweb.tiscali.co.uk/keith.tynan
'00 BRG Sprint ST 'Wolfram'


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