According, once again, to Sheldon, the difference in spacing between 7- and 8-speed cassettes/freewheels is only 0.2mm (5.0 vs. 4.8mm). It would be a really great thing if it were possible to line up seven "six-speed" cogs (5.3mm each) onto an 8-speed hub. Indeed, perhaps someone has done this! Though, of course, the argument could be made that six speeds are just fine...
Thanks very much for your responses! They've been very helpful.
Adam Hammond Toronto, ON, Canada
On 4-Dec-07, at 4:23 PM, John Betmanis wrote:
> At 03:33 PM 04/12/2007 -0500, Adam Hammond wrote:
>
>> However, friction shifting and ramped cassettes (from what I read)
>> don't appear to go well together. It seems that "ghost shifting" is a
>> problem. I'm only planning on running 8 gears in the back, so things
>> aren't as narrow as a 9 or 10 speed setup would be. But it seems like
>> it would still be a problem.
>
> I don't think having a freewheel or cassette has anything to do
> wiith it.
> My Nuovo Record RD works really well with a 7-speed Shimano
> freewheel with
> the "funny teeth". In fact, it runs quietly even when it's off a
> bit, which
> can result in auto-shifting to the next gear. Thing is, with the
> cogs so
> closely spaced, it's very easy to over-shift. With 8 cogs the
> problem would
> be worse and would need a delicate and precise touch. That's where
> index
> shifters would be more foolproof, assuming, of course, that
> everything is
> adjusted spot-on. (Many years ago I used to wonder why derailleurs
> couldn't
> be index shifted the same as hub gears and concluded it was because
> a cable
> could not be depended upon to stay in adjustment for very long to
> shift 4
> or 5 cogs. I remember getting my son a bike with index shifting, and
> sure
> enough, one day he couldn't get any gears without a lot of noise and
> I had
> to fiddle with the cable adjustment. Most other kids would have
> taken it to
> the bike shop, the same as people now take their computer controlled
> cars
> to the dealer.)
>
> Anyway, with 8 cogs on the back, you'll have 16 or 24 gears. Do you
> really
> need them all? How did we ever manage to get by with 3, 4 or 5 fifty
> years
> ago?
>
>
> John Betmanis
> Woodstock, Ontario
> Canada