On Dec 3, 2:56 pm, Steve Palincsar <[EMAIL PROTECTED]> wrote:
> According to the table on Sheldon's sitehttp://sheldonbrown.com/k7.html
> both sprocket thickness and spacer thickness changed between Shimano
> Hyperglide 7 and Shimano 8.  The 7spd is 1.85mm sprocket thickness,
> 3.15mm spacer thickness, and the 8 is 1.8mm sprocket thickness and 3.0mm
> spacer thickness.  Center to center spacing went from 5.0mm for 7 spd
> Hyperglide to 4.8mm for 8spd.

The cag spacing does not matter that much.  What matters is the hub
type.  The 6/7 speed hub requires less dish that an 8 speed hub
because Shimano increased the hub size to accomodate more speeds when
they went from  7 to 8 speeds.  7 and 8 speeds are very close.  You
can even use the same shifters in most cases.

Here is a neat trick if you want more speeds with minimum dish:  use a
7 speed freehub with 9 speed cogs, but leave one of the cogs out of
the mix.  This give you the best of both worlds:  more speeds, good
economy, stronger wheels....

Chris

tallsteelbikes.googlepages.com



On Dec 3, 2:56 pm, Steve Palincsar <[EMAIL PROTECTED]> wrote:
> On Wed, 2008-12-03 at 11:25 -0800, tallsteelbikes wrote:
> > The cog spacing got tighter when they went from 6 to 7 not from 7 to 8
> > speed.
>
> According to the table on Sheldon's sitehttp://sheldonbrown.com/k7.html
> both sprocket thickness and spacer thickness changed between Shimano
> Hyperglide 7 and Shimano 8.  The 7spd is 1.85mm sprocket thickness,
> 3.15mm spacer thickness, and the 8 is 1.8mm sprocket thickness and 3.0mm
> spacer thickness.  Center to center spacing went from 5.0mm for 7 spd
> Hyperglide to 4.8mm for 8spd.
>
> > So if you want a stronger wheel with less dish go with 7 speeds or
> > less on a 7 speed freehub cassette system or a 5/6/7 speed freewheel
> > system.
>
> Or, as others have suggested, you can use an asymmetric rim.
>
> > Who really needs or wants 8/9/10 speeds
>
> For some applications the closer spacing of gears (not sprockets) gives
> you some advantages.  To me those advantages primarily apply to lightly
> loaded bikes.  When I pack on some cargo, I find I lose momentum quickly
> enough that the 1-tooth gear changes that seem so nice and handy on an
> unloaded bike become insignificant piddling hardly worth shifting for.
>
> >  and weaker wheels with more cost and maintenance anyway?
>
> Not a given, as far as I'm concerned.  Maintenance is no different;
> chain and sprocket life seem to be the same.  
>
> >   Only reason is if you are stuck on STI
> > or just need the latest gadgets to keep up with the Jones'.
>
> And we haven't even mentioned the 2009 Campagnolo Super Record group --
> the one they should have called the Spinal Tap Gruppo (because it goes
> to 11).  I think bikesnobnyc's take on that fully represents my
> position.
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