Re: FFS - front freewheel system

[meb]

Jeff Wills wrote:
> Sheldon Brown <[email protected]> wrote in message
> news:<[email protected]>...
> > > Also, where is the front freewheel exactly? Is the BB shell the
> > > standard size, or is there something special about it?
> >
> > It's attached to the bottom bracket spindle. This precluded use of a
> > standard square taper BB for clearance reasons, so they use an early
> > "Octalink" splined setup that turned out to be rather unsatisfactory.
> >
> > There was also a variant that used a one-piece crank, fitting into a
> > standard American-type bottom bracket shell. I used these to make
> > coastable kidback tandem cranks when my kids were little.
> To answer a question Sheldon missed: the BB shell on your Panasonic
> should be a standard 68mm width English thread unit. IIRC, once you get
> the arms off the spindle, the left cone unscrews from the spindle and
> the bearings fall on the floor. After removing the spindle to the right
> (and dropping more bearings), you'll see that the cups threaded in the
> frame have internal splines. I *think* the tool that fits these splines
> is the standard Shimano freewheel removal tool.
> A note: the rear cogset had a limited freewheel action built into it.
> If something jammed the chain, this would allow the rear wheel to
> continue to turn. It felt like a conventional freewheel with *really*
> tight bearings.
> Jeff



Am I correct in assuming this limitted freewheel action would preclude
the rear cogset from being used for a 5 speed fixie?

Was this limitted freewheel action limitted enough to provide
significant braking?

Was there any weight difference on the FF rear 5 speed cogset from a 5
speed freewheel or were they comparable?



--

 

[Jeff Wills]

meb <[email protected]> wrote in message news:<[email protected]>...
> Jeff Wills wrote:
<snipedy-doo-dah>
> > A note: the rear cogset had a limited freewheel action built into it.
> > If something jammed the chain, this would allow the rear wheel to
> > continue to turn. It felt like a conventional freewheel with *really*
> > tight bearings.
> > Jeff
>
> Am I correct in assuming this limitted freewheel action would preclude
> the rear cogset from being used for a 5 speed fixie?
>

Aside from the fact a "5-speed fixie" would make a hash of any
conventional rear derailleur, yes. I think the purpose of the limited
freewheel was to allow the rear wheel to keep turning if something (a
pants cuff, for instance) caught in the the chain.


> Was this limitted freewheel action limitted enough to provide
> significant braking?
>

No.

> Was there any weight difference on the FF rear 5 speed cogset from a 5
> speed freewheel or were they comparable?
>

AFAIK, they were comparable. They were both solid chunks of steel.

Jeff

 

[A Muzi]

> Jeff Wills wrote:
> > > > Also, where is the front freewheel exactly? Is
the BB shell the
> > > > standard size, or is there something special
about it?


> > Sheldon Brown <[email protected]> wrote in message
> > news:<[email protected]>...
> > >
> > > It's attached to the bottom bracket spindle. This precluded use of a
> > > standard square taper BB for clearance reasons, so they use an early
> > > "Octalink" splined setup that turned out to be rather unsatisfactory.
-snip informative stuff-

meb wrote:
> Am I correct in assuming this limitted freewheel action would preclude
> the rear cogset from being used for a 5 speed fixie?
> Was this limitted freewheel action limitted enough to provide
> significant braking?
> Was there any weight difference on the FF rear 5 speed cogset from a 5
> speed freewheel or were they comparable?

The freewheel for an FFS/PPS has stiffer than normal
resistance and will allow a chain to bunch up when coasting
if you remove the FFS/PPS crank system.

If you set it up as a single speed ( You misuse the term
"fixie") by shortening the chain to one of the five
sprockets, yes, you can ride it effectively. Just don't
include a derailleur or tensioner unless you have the
special crank assembly.

The crank spline is the "Selecta" pattern which started the
early "standard" called "Octa-8" long before "octalink."

No, you will get no noticeable braking effect. Keep your
front caliper.

On a hi-ten frame with steel hubs, cranks and rims the
freewheel weight, while substantial, isn't all that
significant.

You may substitute a normal 5 or 6 freewheel ( or even a
single for that matter) on the hub you have.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[meb]

A Muzi wrote:
> > Jeff Wills wrote:
> > > > > Also, where is the front freewheel exactly? Is
> the BB shell the
> > > > > standard size, or is there something special
> about it?
> > > Sheldon Brown <[email protected]> wrote in message
> > > news:<[email protected]>...
> > > >
> > > > It's attached to the bottom bracket spindle. This precluded use
> > > > of a standard square taper BB for clearance reasons, so they use
> > > > an early "Octalink" splined setup that turned out to be rather
> > > > unsatisfactory.
> -snip informative stuff-
> meb wrote:
> > Am I correct in assuming this limitted freewheel action would preclude
> > the rear cogset from being used for a 5 speed fixie? Was this limitted
> > freewheel action limitted enough to provide significant braking? Was
> > there any weight difference on the FF rear 5 speed cogset from a 5
> > speed freewheel or were they comparable?
> The freewheel for an FFS/PPS has stiffer than normal resistance and
> will allow a chain to bunch up when coasting if you remove the FFS/PPS
> crank system.
> If you set it up as a single speed ( You misuse the term "fixie") by
> shortening the chain to one of the five sprockets, yes, you can ride it
> effectively. Just don't include a derailleur or tensioner unless you
> have the special crank assembly.
> The crank spline is the "Selecta" pattern which started the early
> "standard" called "Octa-8" long before "octalink."
> No, you will get no noticeable braking effect. Keep your front caliper.
> On a hi-ten frame with steel hubs, cranks and rims the freewheel weight,
> while substantial, isn't all that significant.
> You may substitute a normal 5 or 6 freewheel ( or even a single for that
> matter) on the hub you have.
> --
> Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971



Not sure why the term fixie is missused. Is it because a 5 speed non-
freewheeling drive (times any crankset ring quantities) is not a “fixie”
if gears can be changed?

Regarding the tensioner issue raised: I was considering constructing a
tensioner from the RANS double idler assembly
http://www.shoprans.com/DriveLine.asp configured to move to take in
tension from sprocket changes as well as allow the return chain side to
switch to tension when the crank speeds slow below wheel speed. The
double idlers are designed to work on the chain drive side as well as
return side. Is there a nonobvious tensioner issue with “fixies”
overlooked?

This would be tried on a recumbent.



--

 

[A Muzi]

-snip much-
> > meb wrote:
> > > Am I correct in assuming this limitted freewheel action would preclude
> > > the rear cogset from being used for a 5 speed fixie? Was this limitted
> > > freewheel action limitted enough to provide significant braking? Was
> > > there any weight difference on the FF rear 5 speed cogset from a 5
> > > speed freewheel or were they comparable?

> A Muzi wrote:
> > The freewheel for an FFS/PPS has stiffer than normal resistance and
> > will allow a chain to bunch up when coasting if you remove the FFS/PPS
> > crank system.
> > If you set it up as a single speed ( You misuse the term "fixie") by
> > shortening the chain to one of the five sprockets, yes, you can ride it
> > effectively. Just don't include a derailleur or tensioner unless you
> > have the special crank assembly.
-snip-

meb wrote:
> Not sure why the term fixie is missused. Is it because a 5 speed non-
> freewheeling drive (times any crankset ring quantities) is not a “fixie”
> if gears can be changed?
-snip-

The FFS freewheels coasts. It's a freewheel, not fixed.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[meb]

A Muzi wrote:
> -snip much-
> > > meb wrote:
> > > > Am I correct in assuming this limitted freewheel action would
> > > > preclude the rear cogset from being used for a 5 speed fixie?
> > > > Was this limitted freewheel action limitted enough to provide
> > > > significant braking? Was there any weight difference on the FF
> > > > rear 5 speed cogset from a 5 speed freewheel or were they
> > > > comparable?
> > A Muzi wrote:
> > > The freewheel for an FFS/PPS has stiffer than normal resistance
> > > and will allow a chain to bunch up when coasting if you remove the
> > > FFS/PPS crank system. If you set it up as a single speed ( You
> > > misuse the term "fixie") by shortening the chain to one of the
> > > five sprockets, yes, you can ride it effectively. Just don't
> > > include a derailleur or tensioner unless you have the special
> > > crank assembly.
> -snip-
> meb wrote:
> > Not sure why the term fixie is missused. Is it because a 5 speed non-
> > freewheeling drive (times any crankset ring quantities) is not a
> > “fixie” if gears can be changed?
> -snip-
> The FFS freewheels coasts. It's a freewheel, not fixed.
> --
> Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971



So a Schlumpf BB drive with fixie hub is semantically a fixie even
though multi speed.



--

 

[Adam Rush]

> So a Schlumpf BB drive with fixie hub is semantically a fixie even
> though multi speed.

Schlumpf themselves say that is it right out. From their FAQ:

"9. Can speed-drive be used with a fixed wheel cycle?

"No. In reverse direction, there musn't be full load. It's o.k. for
actuating a coaster brake, but not for high torques during long
operation periods."


If anybody could give me some technical reasons for this FAQ answer,
other than that they are covering their asses, I would appereciate it.

 

[A Muzi]

> > -snip much-
> > > > meb wrote:
> > > > > Am I correct in assuming this limitted freewheel action would
> > > > > preclude the rear cogset from being used for a 5 speed fixie?

note use of "freewheel" and "fixed gear" together.

> > > A Muzi wrote:
> > > > The freewheel for an FFS/PPS has stiffer than normal resistance
> > > > and will allow a chain to bunch up when coasting if you remove the
> > > > FFS/PPS crank system. If you set it up as a single speed ( You
> > > > misuse the term "fixie") by shortening the chain to one of the
> > > > five sprockets, yes, you can ride it effectively. Just don't
> > > > include a derailleur or tensioner unless you have the special
> > > > crank assembly.
> > -snip-

> > meb wrote:
> > > Not sure why the term fixie is missused. Is it because a 5 speed non-
> > > freewheeling drive (times any crankset ring quantities) is not a
> > > “fixie” if gears can be changed?
> > -snip-

> A Muzi wrote:
> > The FFS freewheels coasts. It's a freewheel, not fixed.

meb wrote:
> So a Schlumpf BB drive with fixie hub is semantically a fixie even
> though multi speed.

Yes, I think we agree. "Fixed" implies no coasting.
Freewheels, whether one or eight speeds, are not fixed.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[David Damerell]

Adam Rush <[email protected]> wrote:
>Schlumpf themselves say that is it right out. From their FAQ:
>"9. Can speed-drive be used with a fixed wheel cycle?
>"No. In reverse direction, there musn't be full load. It's o.k. for
>actuating a coaster brake, but not for high torques during long
>operation periods."
>If anybody could give me some technical reasons for this FAQ answer,
>other than that they are covering their asses, I would appereciate it.

I'm not sure what you mean; manifestly it's harder to design a planetary
gear that must withstand high torque in both directions.
--
David Damerell <[email protected]> flcl?

 

[Benjamin Lewis]

David Damerell wrote:

> Adam Rush <[email protected]> wrote:
>> Schlumpf themselves say that is it right out. From their FAQ:
>> "9. Can speed-drive be used with a fixed wheel cycle?
>> "No. In reverse direction, there musn't be full load. It's o.k. for
>> actuating a coaster brake, but not for high torques during long
>> operation periods."
>> If anybody could give me some technical reasons for this FAQ answer,
>> other than that they are covering their asses, I would appereciate it.
>
> I'm not sure what you mean; manifestly it's harder to design a planetary
> gear that must withstand high torque in both directions.

Maybe if you know the details of how they are designed. I never realized
they were not symmetrical.

--
Benjamin Lewis

Amoebit:
Amoeba/rabbit cross; it can multiply and divide at the same time.