On 4 Nov 2004 21:28:32 -0800
[email protected] (Jeff Wills) wrote:
> [email protected] (Sheldon Brown) wrote in message
> news:<[email protected]>...
> > I'm not sure which part of the AOLers message Jeff thinks is "wrong"
> > but I don't believe it is.
> >
> > The 9- and 10-speed sprockets are thinner in the middle, but there's
> > no difference in the thickness of the teeth.
> >
>
> OK, now I'm really confused, Sheldon. There's a chart on your page:
> http://www.sheldonbrown.com/gloss_sp-ss.html
> that says Shimano 10-speed cogs are 1.6mm thick with a 2.35mm spacer
> between them. That same chart says that Shimano 9-speed cogs are
> 1.78mm thick with a 2.56mm spacer.
>
> This *implies* that the 10-speed chain is substantially narrower
> between the inner plates than a 9-speed chain, making it difficult or
> impossible to run a Shimano 10-speed chain on the OP's 9-speed XTR
> chainrings.
>
> What am I missing?
My take on that is that he is referring to the size with regard to
building up custom cassettes, and that the 10 speed cogs and spacers are
just milled differently, but this could be made clearer.
The concept here is that the interior dimensions of the links remain
the same, but the outer edges of the chain obviously have to be slightly
more streamlined to fit between the closer spaced but still the same tooth
size cogs.
Got me how they do it. I have noticed, for example, that SRAM PC-58
chain as compared to, say KMC Z-72 chain, seems to have a smoother profile,
even though both chains are advertised as being for 8 speed cogs and as
being HG and IG compatible, and both work quite acceptably on 8 speed
configurations. I imagine there is more that can be done. Perhaps the
plates are thinner and the pins slightly shorter?
I imagine if you took a 10 speed chain and held it next to a 9 speed
chain and an 8 speed chain from the same maker, the differences would
become obvious, and that you could easily measure said differences with a
$20 set of chinese digital calipers from harbor freight.
I still question the need for more cogs than maybe 7 given the same
lowest and highest cog, but to each his own. I'm happy with my 8 speed
setup, especially considering how cheaply the parts go on ebay, now that
it's been rendered entirely ghetto by the advent of 10 speed cogs.
My brother-in-law rides an aluminum comfort bike with a single 34 tooth
chain ring and a 7 speed 12-28 cassette in the back. Couldn't be happier
and spent all of $98 on the thing. I went for a ride with him a few weeks
ago and was afraid he might slow down so much I might have to drop into one
of those gears where it becomes tricky to keep my swb 'bent vertical . . .
)
