Jerry,
It isn't only the Shimano freewheels that are wider than the older European units. Suntour freewheels are also wider, if only because of the extra flange on their innermost surface. It's one reason why, when used with older European frames, they cause the chain to rub on the seatstay unless you change the spacing in some manner.
In fact, I always surmised that this is why the French bikes often used 122mm - rather than 120mm - spacing. (Of course, that was just a guess.) Also, if you look at older Italian frames, you might notice that the inside surfaces of the seatstays rarely are "relieved" for clearance at the junction with the driveside dropout. Sometimes, there is provision for a small amount of extra clearance, but it never is really that significant. This is because Regina freewheels, and others with a similar style of construction, are so narrow.
You'll see that on later frames - i.e. ones that were built when Suntour freewheels had become so popular - the inside surface of the chainstay is "massaged" to provide more clearance. Anyway, it's another reason why - in my view anyway - spreading an old 120mm frame to 126mm isn't such a crime if you're going to switch to a modern 5 sprocket freewheel.
Best regards,
Fred Rednor
> From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
\r?\n> Subject: Re: [CR]Freewheel Spacing??
\r?\n> To: thomasthomasa@yahoo.com, "Classic Rendezvous" <classicrendezvous@bikelist.org>
\r?\n> Date: Saturday, August 23, 2008, 11:17 AM
\r?\n> That's a good point, but the outside of the inner cog is
\r?\n> also clearly closer to the inside face of the DO, which is
\r?\n> not a function of outer cog size. And, most conclusively, I
\r?\n> laid the two FW's side-by-side and the Shimano stacks
\r?\n> higher by nearly one cog. So I'm convinced that either
\r?\n> the Shimano cogs were thicker at their base, or they used
\r?\n> thicker spacers, or both.
\r?\n>
\r?\n> Now that I think about, it, I believe I've observed
\r?\n> in the past that Shimano FW's give significantly less
\r?\n> clearance between the outside cog and the stays than any
\r?\n> other brand, even with the same number of teeth on the small
\r?\n> cog. Until now I didn't think a lot about it as it was
\r?\n> usually just a matter of more difficultly in changing the
\r?\n> wheel, rather than the chain actually rubbing the stay.
\r?\n>
\r?\n> Regards,
\r?\n>
\r?\n> Jerry Moos
\r?\n> Big Spring, Texas, USA
\r?\n>
\r?\n> Thomas Adams <thomasthomasa@yahoo.com> wrote:
\r?\n> Dear Jerry:
\r?\n>
\r?\n> The Shimano may be wider than the Atom, but don't
\r?\n> forget using a 16 instead of a 14 tooth small cog lifts the
\r?\n> chain up higher, and therefore closer to the seatstay which
\r?\n> is slanting in as it moves from drop out to seatlug.
\r?\n>
\r?\n> The only fix I can think of is to respace the rear hub to
\r?\n> 122mm or so by adding a washer or two, so as to splay the
\r?\n> seatstay out a tad more away from the new chainline. Good
\r?\n> luck.
\r?\n>
\r?\n> Tom Adams
\r?\n> Manahttan, KS, USA
\r?\n>
\r?\n> --- On Sat, 8/23/08, Jerome & Elizabeth Moos
\r?\n> <jerrymoos@sbcglobal.net> wrote:
\r?\n>
\r?\n> From: Jerome & Elizabeth Moos
\r?\n> <jerrymoos@sbcglobal.net>
\r?\n> Subject: [CR]Freewheel Spacing??
\r?\n> To: "Classic Rendezvous"
\r?\n> <classicrendezvous@bikelist.org>
\r?\n> Date: Saturday, August 23, 2008, 9:39 AM
\r?\n>
\r?\n>
\r?\n> Recently ordered a custom 16-34 Shimano 5 speed FW from
\r?\n> Loose Screws for my 1972 Follis 172, as I intended to
\r?\n> commute on it with a fairly heavy large laptop in the
\r?\n> pannier, and one short but steep hill on the way to work.
\r?\n> The FW arrived yesterday. But when installed the
\r?\n> Shimano FW in place of the 14-28 Atom, the chain rubbed the
\r?\n> seatstay when on the small cog. This is a newer Chinese
\r?\n> made FW body, with a mix of new and NOS cogs. It appears
\r?\n> the Shimano is simply wider than the Atom. The lip behind
\r?\n> the inner cog that butts against the hub shell doesn't
\r?\n> seem much different, so I think ether the cogs are thicker,
\r?\n> or the spacers thicker, or both. Probably more the
\r?\n> spacers, as the cogs cannot be too much thicker and still
\r?\n> accept 3/32 chain. Both the Atom and Shimano are
\r?\n> supposedly "normal" 5 speed spacing, but the
\r?\n> Shimano is quite obviously wider. Has anyone else observed
\r?\n> significant variation in the actual spacing of FW's of
\r?\n> different brands?
\r?\n> There were of course the SunTour Ultras and narrow spaced
\r?\n> FW's from other manufacturers, but it appears even
\r?\n> "normal" spaced FW's varied a lot. Was
\r?\n> Shimano notorious for having wider spacing than others?
\r?\n> Did most manufacturers use the same spacers for
\r?\n> "normal" 5-speed as for "normal" 6
\r?\n> speed, or was even the "normal" 6 speed spacing a
\r?\n> bit narrower than 5 speed? Are there thinner spacers that
\r?\n> will fit a Shimano 5 speed FW? Regards,
\r?\n> Jerry Moos Big Spring, Texas, USA --- StripMime
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