Freewheels

It may have occurred to other observers, but to me the many new and
noisy ratchet escapements are a symptom of gearing that was not around
30 years ago when Regina (Italy) and a few French brands were the
mainstay. At the end of that era, Regina introduced a new ratchet
pawl having a cylindrical belly at its rear underside with its center
of rotation above the flat back of the pawl.

The offset pivot got rid of the ever present clicking as well as
making return springs into simple clasping spring clips that retain
pawls during FW assembly. However, that didn't last long. About that
time MTB's with three times smaller CW's began to appear with over 30t
low gear driven sprockets, putting huge forces on FW's.

Most old school FW's had a 26t large sprocket driven by no lower than
39t CW, ala Campagnolo record cranks, roughly a 1.2:1 ratio and the
crank to chain leverage less than 2:1. That means that torque on the
FW pawl was enough to exert 500lbf on a pawl inside the FW. As a
result of these greatly lower gears failures occurred to which the
first response was multiple pawl engagements and face ratchets that
engaged all teeth at thee same time.

Multiple engagement ratchets overlook that at least once per
revolution only a single pawl carries the entire load and can fail as
easily as that that didn't bother with this feature. After all, a
good Regina road FW had two pawls 180 degrees apart and 21 ratchet
ramps, making 42 clicks per revolution. That's reasonable resolution
compared to may 16 and 18 clicks today or the face spline (Hugi) that
clack like a burglar alarm when coasting.

I was pleasantly surprised that Shimano in their freehubs resolved
several issues in one fell swoop. Axle bearings are at the outer end
of the FW and left side of the hub, reducing the possibility of axle
breakage, no threads are affects by pedaling torque so no FW or
sprockets become unremovably tight. The pawls use offset pivots and
engage one at a time, giving 20 clicks per revolution that are as good
as not audible. The wheel bearings are nine 1/4" balls per side and
are well protected from road splash.

I recently changed for Campagnolo Record rear hubs to Shimano cassette
hubs after breaking many axles that also broke two rear dropouts over
the years. After switching to these, I discovered that 7-speed hubs
are getting scarce, but then I found enough of them to last a long
time. I'm not aware that these units were ever offered in a fewer
sprocket form, but I am not enamored with the 11-sprocket FW with
triple CW cranks. I do not want a continuously variable transmission
or an automatic one, although such devices are available.

Jobst Brandt

wrote:
It may have occurred to other observers, but to me the many new and
noisy ratchet escapements are a symptom of gearing that was not around
30 years ago when Regina (Italy) and a few French brands were the
mainstay. At the end of that era, Regina introduced a new ratchet
pawl having a cylindrical belly at its rear underside with its center
of rotation above the flat back of the pawl.

Shimano flirted with having the bearings inboard of the freehub body again:

http://techdocs.shimano.com/media/te...9830608915.pdf

and

http://techdocs.shimano.com/media/te...9830608916.pdf

and then seem to have decided that was a mistake:

http://techdocs.shimano.com/media/te...9830648615.pdf

Harold Rothgar wrote:

It may have occurred to other observers, but to me the many new and
noisy ratchet escapements are a symptom of gearing that was not
around 30 years ago when Regina (Italy) and a few French brands
were the mainstay. At the end of that era, Regina introduced a new
ratchet pawl having a cylindrical belly at its rear underside with
its center of rotation above the flat back of the pawl.

Shimano flirted with having the bearings inboard of the freehub body again:

http://techdocs.shimano.com/media/te...9830608915.pdf

and

http://techdocs.shimano.com/media/te...9830608916.pdf

and then seem to have decided that was a mistake:

http://techdocs.shimano.com/media/te...9830648615.pdf

I don't see any of my hubs, ones with the thin hub tube that is fatter
on the right end where the internal hollow screw retains the freewheel
element of the freehub. Also, my hubs use nine loose 1/4" bearing
balls and use no screw-on axle tips.

I spooked around that web site a bit and found no such hubs. Maybe
they are an older generation that no longer exists in Shimano's mind,
or on their web sites.

If you have any more of these excellent links, let me know.

Thanks,

Jobst Brandt

wrote:

I don't see any of my hubs, ones with the thin hub tube that is fatter
on the right end where the internal hollow screw retains the freewheel
element of the freehub. Also, my hubs use nine loose 1/4" bearing
balls and use no screw-on axle tips.

I spooked around that web site a bit and found no such hubs. Maybe
they are an older generation that no longer exists in Shimano's mind,
or on their web sites.

If you have any more of these excellent links, let me know.


The ones I posted are just the last few Dura-Ace freehubs, where they
tend to introduce new technology (not always successfully).

Where available, the exploded drawings for all Shimano gear are available at

http://techdocs.shimano.com/techdocs/index.jsp

The 105-5500 freehub is typical of the ones I've used:

http://techdocs.shimano.com/media/te...9830612177.pdf

Unfortunately the viewpoint of the drawing doesn't show whether the
centre of the hub body is wider at the right-hand end, but it normally is.

Still Just Me wrote:
On 25 Oct 2008 20:40:38 GMT, wrote:

The offset pivot got rid of the ever present clicking as well as
making return springs into simple clasping spring clips that retain
pawls during FW assembly.

But many of us liked the clicking - long live the click!

Just don't mention the Sturmey-Archer SW hub; a very ill-fated attempt
to get rid of pawl noise. SA hubs click in normal and top gear even
when pedalling, because the low-gear pawls are being overdriven, and
this must have really annoyed someone in the SA design department.

Harold Rothgar wrote:

I don't see any of my hubs, ones with the thin hub tube that is
fatter on the right end where the internal hollow screw retains the
freewheel element of the freehub. Also, my hubs use nine loose
1/4" bearing balls and use no screw-on axle tips.

I spooked around that web site a bit and found no such hubs. Maybe
they are an older generation that no longer exists in Shimano's
mind, or on their web sites.

If you have any more of these excellent links, let me know.

The ones I posted are just the last few Dura-Ace freehubs, where
they tend to introduce new technology (not always successfully).

I have Dura-Ace, Ultegra and 105 rear hubs, all having the same
aluminum body hub except that the Dura-Ace has a grey band with the
Dura-Ace label around its thin section.

Where available, the exploded drawings for all Shimano gear are
available at

http://techdocs.shimano.com/techdocs/index.jsp

The 105-5500 freehub is typical of the ones I've used:

http://techdocs.shimano.com/media/te...9830612177.pdf

Unfortunately the viewpoint of the drawing doesn't show whether the
center of the hub body is wider at the right-hand end, but it
normally is.

That's an entirely different (newer) aluminum hub and seems to common
to several Groups just as the one I have WAS common to several groups.
I guess there aren't any more of the older version in stock.

Jobst Brandt

Harold Rothgar wrote:

I don't see any of my hubs, ones with the thin hub tube that is fatter
on the right end where the internal hollow screw retains the freewheel
element of the freehub. Also, my hubs use nine loose 1/4" bearing
balls and use no screw-on axle tips.

I spooked around that web site a bit and found no such hubs. Maybe
they are an older generation that no longer exists in Shimano's
mind, or on their web sites.

If you have any more of these excellent links, let me know.


The ones I posted are just the last few Dura-Ace freehubs, where
they tend to introduce new technology (not always successfully).

Where available, the exploded drawings for all Shimano gear are
available at:

http://techdocs.shimano.com/techdocs/index.jsp

The 105-5500 freehub is typical of the ones I've used:

http://techdocs.shimano.com/media/te...9830612177.pdf

Unfortunately the viewpoint of the drawing doesn't show whether the
centre of the hub body is wider at the right-hand end, but it
normally is.

Here's view of what I mean:

http://i33.tinypic.com/2881r1i.jpg

Jobst Brandt

a écrit:

Here's view of what I mean:

http://i33.tinypic.com/2881r1i.jpg

That shape used to be common to all Shimano freehubs, from the late eighties
through the mid nineties. MTB hubs adopted the fat "Parallax" shell with
large external seals in about '94. Road hubs kept the right-hand bulge until
the 7700, 6500 and 5500 9-speed series introduced from 1997. The freehub
body attachment spline and hollow bolt are identical for nearly all of these
hubs, despite the change in body shape.

Paul Lange has an archive of diagrams of older Shimano parts, though none of
the hubs you're describing:

http://www.paul-lange.de/produkte/sh...chungen_archiv

Some Shimano mtb hubs are now using oversized aluminium axles with separate
endcaps, and a correspondingly larger hollow allen bolt to attach the
freehub body:

http://www.paul-lange.de/produkte/sh...FH/FH-M770.pdf

James Thomson

In article ,
wrote:

Harold Rothgar wrote:

I don't see any of my hubs, ones with the thin hub tube that is
fatter on the right end where the internal hollow screw retains
the freewheel element of the freehub. Also, my hubs use nine
loose 1/4" bearing balls and use no screw-on axle tips.

I spooked around that web site a bit and found no such hubs.
Maybe they are an older generation that no longer exists in
Shimano's mind, or on their web sites.

If you have any more of these excellent links, let me know.

snip

Unfortunately the viewpoint of the drawing doesn't show whether the
centre of the hub body is wider at the right-hand end, but it
normally is.

Here's view of what I mean:

http://i33.tinypic.com/2881r1i.jpg

I have one of the older 7 speed hubs you mention as well as the Ultegra
6500 9 speed hub. I've never taken either of them apart. Here's the
drawing for the 6500- it seems much like what you describe. I have
found this hub quite reliable:

http://techdocs.shimano.com/media/te...V/bikecomponen
ts/FH/EV-FH-6500-1679_v1_m56577569830611839.pdf

BTW, someone in another forum pointed out to me that if you bracket
long URLs, most newsreaders won't break them if they wrap to another
line.

Tim McNamara wrote:
... I have
found this hub quite reliable:

http://techdocs.shimano.com/media/te...V/bikecomponen
ts/FH/EV-FH-6500-1679_v1_m56577569830611839.pdf

BTW, someone in another forum pointed out to me that if you bracket
long URLs, most newsreaders won't break them if they wrap to another
line.

Hmm. That trick didn't work with Mozilla Thunderbird.