Can you disable the freewheel in a cassette hub?



M

Mark Janeba

Guest
[email protected] wrote:
> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?


If by that you mean "cause the cogs to freewheel in *both* directions,"
I know the answer is yes with Campy, and probably with Shimano too. The
question is, why would you want to? Just take the chain off the bike.

If you mean "stop the cogs from freewheeling at all," there may be ways
to do it, but removing the pawls isn't one of them.

Mark
 
P

Phil, Squid-in-Training

Guest
"Mark Janeba" <[email protected]> wrote in message
news:[email protected]
> [email protected] wrote:
>> I know you can take the pawls out of a real freewheel - can you do the
>> same to cassettes?

>
> If by that you mean "cause the cogs to freewheel in *both* directions," I
> know the answer is yes with Campy, and probably with Shimano too. The
> question is, why would you want to? Just take the chain off the bike.
>
> If you mean "stop the cogs from freewheeling at all," there may be ways to
> do it, but removing the pawls isn't one of them.
>
> Mark
>


I think the OP may have meant fixed.

--
Phil, Squid-in-Training
 
M

MSeries

Guest
[email protected] wrote:
> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?


There are no pawls in a cassette. The ratchet mechanism is in the
freehub body.
 
D

DD

Guest
[email protected] wrote:
> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?
>


Yes you can, the freehub body on which the cassette sits and is bolted
to is itself bolted to the rear hub by way of a 10mm allen bolt. It is
by this arrangement that you can also swap Campy, whatever and Shimano
freehubs if you wish. From memory you have to remove the freehub from
the rear hub to open it up. Not much different then from operating on a
freewheel.
I did this some time ago so that I could make a mid-drive for a
recumbent, I needed a desexed freehub body to hold my cogset. The only
good reason to do butcher a cassette hub.

If you have this in mind then your local LBS might have some of the
older Shimano freehubs from before they changed to the current irregular
spline pattern, these will be cheap, almost throwaways.
 
Martin Skank writes:

>> I know you can take the pawls out of a real freewheel - can you do
>> the same to cassettes?


> There are no pawls in a cassette. The ratchet mechanism is in the
> freehub body.


What you mean no ratchet. What do you think goes click-click when you
backpedal? Hugi used a face spline that went CLACK-CLACK and that
piece of hardware can be replaced by a solid block to make a multi
speed fixed cluster... or for that matter left out to make a freely
rotating sprocket cluster. With Pawls removed, any freewheel can be
made to rotate in both directions. I take it this is to be a
multi-speed idler or the like? Sounds odd. Let's hear more about this.

Jobst Brandt
 
[email protected] wrote:
> Martin Skank writes:
>
> >> I know you can take the pawls out of a real freewheel - can you do
> >> the same to cassettes?

>
> > There are no pawls in a cassette. The ratchet mechanism is in the
> > freehub body.

>
> What you mean no ratchet. What do you think goes click-click when you
> backpedal? Hugi used a face spline that went CLACK-CLACK and that
> piece of hardware can be replaced by a solid block to make a multi
> speed fixed cluster... or for that matter left out to make a freely
> rotating sprocket cluster. With Pawls removed, any freewheel can be
> made to rotate in both directions. I take it this is to be a
> multi-speed idler or the like? Sounds odd. Let's hear more about this.
>
> Jobst Brandt


jb (the real jb), this "Martin Skank" is being pedantic. If you refer
to the assemblage of cogs as a cassette, then yes there are no pawls in
it. What I'm after is a freely rotating assemblage of cogs, and the
outboard bearing of a cassette hub may be an advantage.

Yes, it's for a multi-speed idler, for an in-line tricycle.
 
Z

Zog The Undeniable

Guest
[email protected] wrote:

> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?
>

You can weld one up or buy one of the (expensive) adaptors that change
your hub into a fixed.
 
P

Peter Cole

Guest
[email protected] wrote:
> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?
>


Yes. A Shimano freehub body is attached to the freehub shell with a 10mm
bolt, and the cup (has to be removed to get to pawls) has notches for a
special tool (I put FHB in a vise and used a trimmed piece of bar
stock). The FHB has lots of tiny ball bearings, but the the pawls (2)
are retained with a light spring clip, simple to remove.
 
J

JeffWills

Guest
[email protected] wrote:

>
> jb (the real jb), this "Martin Skank" is being pedantic. If you refer
> to the assemblage of cogs as a cassette, then yes there are no pawls in
> it. What I'm after is a freely rotating assemblage of cogs, and the
> outboard bearing of a cassette hub may be an advantage.
>
> Yes, it's for a multi-speed idler, for an in-line tricycle.


Here's a couple different ways of doing this:
http://www.recumbents.com/wisil/jackshaft/jackshaft.htm
(both conventional freewheel and cassette)

These are somewhat common on recumbent bikes equipped with mid-drive
arrangements.

Jeff
 
S

Sheldon Brown

Guest
[email protected] wrote:

> Yes, it's for a multi-speed idler, for an in-line tricycle.


This will work, but you would be better off, if your frame design
permits, using the main bearings of an actual rear hub/axle, rather than
the coasting bearings of the Freehub body.

The main axle bearings are designed to handle much greater loads. The
coasting bearings use tiny little 1/8" balls, and are not normally under
any significant load when they are turning.

For those who understood the question to deal with making a fixed gear,
I can say that I've done this by brazing, running a bead of brass around
the back side of the Freehub body. Works great, gives me a two speed
fixed gear that I can change without needing to slide the wheel out of
the stupid backwards fork ends of my Bianchi B.a.S.S.

Sheldon "http://sheldonbrown.com/bass" Brown
+--------------------------------------------------------------+
| When I think back on all the **** I learned in high school |
| It's a wonder I can think at all |
| And though my lack of education hasn't hurt me none |
| I can read the writing on the wall --Paul Simon |
+--------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
 
R

ron

Guest
On Tue, 29 Nov 2005 06:40:03 -0800, mbn wrote:

> I know you can take the pawls out of a real freewheel - can you do the
> same to cassettes?


If what you want is to make it fixed, yes. You can braze it solid.
Sheldon Brown has an article that touches on this, but it doesn't go into
complete detail. There was a real good article on it elsewhere, but I
can't find it any more. There are, however, some articles about tearing
one of these down, e.g.,

http://www.icebike.org/Equipment/freehub.htm

I studied up on this and ended up doing it - brazing a freehub body to
make it fixed, and refitting the hub with a solid axle and track nuts.

One trick was to put back the little 1/8" ball bearings (completely clean
and dry, though) inside the freehub body before brazing, so as to get
everything into proper alignment before locking it up for good.

Some people have reported the brazed freehub body not being quite square
with the axle. Putting the bearings back in before brazing helps avoid
this.

Another issue is understanding that the outer bearing cup is attached with
left-handed threads (while the 10mm fixing bolt that holds on the entire
freehub body is right-handed).

Yet another issue is getting enough grip to remove the fixing bolt -
doing this while the hub is still spoked to the rim makes it a LOT easier.

The brazing is done around the back of the freehub body (but avoiding
getting braze onto the splines).

The brazing did kill some of the temper on the freehub body, but not far
enough down the splines to be close to where the cog engages. It is
working great. I have not babied it at all.

One advantage of this solution over a Surly Fixer is that you can run a
smaller cog (down to 12T) - so you get much more choice of gearing. It is
also dirt cheap, and the dishing situation is no worse than a geared
wheel, which is certainly no real problem. Works great with a 14T BMX cog
and PVC spacers.
 
S

Sheldon Brown

Guest
ron wrote:

> On Tue, 29 Nov 2005 06:40:03 -0800, mbn wrote:
>
>
>>I know you can take the pawls out of a real freewheel - can you do the
>>same to cassettes?

>
>
> If what you want is to make it fixed, yes. You can braze it solid.
> Sheldon Brown has an article that touches on this, but it doesn't go into
> complete detail.


There's as much detail as anybody needs at:

http://sheldonbrown.com/bass

> There was a real good article on it elsewhere, but I
> can't find it any more. There are, however, some articles about tearing
> one of these down, e.g.,
>
> http://www.icebike.org/Equipment/freehub.htm
>
> I studied up on this and ended up doing it - brazing a freehub body to
> make it fixed, and refitting the hub with a solid axle and track nuts.
>
> One trick was to put back the little 1/8" ball bearings (completely clean
> and dry, though) inside the freehub body before brazing, so as to get
> everything into proper alignment before locking it up for good.


Yes, that's essential. That's why I never even bothered to take mine apart.

It's not clear to me why you replaced the axle...I find quick release
much more convenient.

> Some people have reported the brazed freehub body not being quite square
> with the axle. Putting the bearings back in before brazing helps avoid
> this.


Yep, also being careful not to get lumps of brass on the backside or
into the mounting splines.

> Another issue is understanding that the outer bearing cup is attached with
> left-handed threads (while the 10mm fixing bolt that holds on the entire
> freehub body is right-handed).


Not an issue if you don't disassemble the Freehub body.

> Yet another issue is getting enough grip to remove the fixing bolt -
> doing this while the hub is still spoked to the rim makes it a LOT easier.
>
> The brazing is done around the back of the freehub body (but avoiding
> getting braze onto the splines).
>
> The brazing did kill some of the temper on the freehub body, but not far
> enough down the splines to be close to where the cog engages. It is
> working great. I have not babied it at all.


Even annealed, a steel body is going to be way harder than an aluminum
one. Besides, for fixed gear you don't generally run low enough ratios
to put serious stress on the splines.
>
> One advantage of this solution over a Surly Fixer is that you can run a
> smaller cog (down to 12T) - so you get much more choice of gearing. It is
> also dirt cheap, and the dishing situation is no worse than a geared
> wheel, which is certainly no real problem.


Actually, you can get track hubs down to 12 also, but they are 'spensive.

Another advantage of this setup, as opposed to the Fixxer, is that you
can achieve any desired chainline by re-arranging the spacers.

> Works great with a 14T BMX cog


Yep. Mine has a 14 and an 18, with a 38-42 double crankset. I commuted
on it today, using the 42/14. I'll prob'ly switch it to the 38/18
tomorrow on accounta we're expecting serious snow...

Details at: http://sheldonbrown.com/bass

Sheldon "Ugly Green Bike" Brown
+------------------------------------------------+
| How about a Harris Cyclery gift certificate? |
| http://harriscyclery.com/gift |
+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
 

>jb (the real jb), this "Martin Skank" is being pedantic. If you refer
>to the assemblage of cogs as a cassette, then yes there are no pawls in
>it. What I'm after is a freely rotating assemblage of cogs, and the
>outboard bearing of a cassette hub may be an advantage.
>
>Yes, it's for a multi-speed idler, for an in-line tricycle.


You can do it and it works. I have done it. Here is a photo of my
bike: http://tinyurl.com/7wvns

I embedded a rear wheel hub in the frame and use a free-spinning
free-hub body and restacked 8-speed cassette as a mid drive and I use
the hubs original wheel axle as the suspension pivot.

There are a few things to watch out for when using a casette this
way...

1) The cogs of a typical cassette are designed to be driven and to
shift easily, not to drive. In order to make this type of mid-drive
work, you must restack the cogs, with the one that drives the rear
wheel flipped over (that means about 3 minutes of work with a hand
file to make it fit back on the free-hub body). If you don't flip the
rear wheel drive cog, you'll find as I did, that when you pedal hard
the rear chain will just slip over the teeth of the drive cog.

2) The chain line will require careful attention. On my bike the
rear wheel cassette and mid drive cassette are in exact alignment
because I used parallel stays and a rear wheel axle as the suspension
pivot. The rear drive cog is the largest on the mid-drive and is
closest to the bike frame. This works fine for driving all 8 cogs at
the rear wheel but there is one bugaboo. When the rear chain is on
any but the largest 3 cogs at the rear wheel, if I pedal backwards (as
one might do to adjust pedal position when stopped at a traffic
signal) the chain will throw itself off the drive cog at the mid-drive
(it is doing what it was designed to do- trying to shift gears). I
have solved that problem by adding a plastic disc about 7" in
diameter, cut from the lid of a plastic bucket and installed between
the rear drive cog and the next one on the mid-drive. The plastic
applies just enough side pressure to the chain to keep it from coming
off when I pedal backwards. I have since come to realize that if I
try to start the bike up from a stop on level ground in any but the
largest 3 cogs on the rear wheel I am in trouble anyway, so if you
develop the habit of downshifting the rear derailleur before stopping
(which is sort of normal anyway), you may not need to bother with such
a disc. A better solution would be to buy or make a rear wheel drive
cog without and easy-shift ramping. You might also try offsetting the
mid drive so the rear drive cog lines up with the middle of the rear
wheel cassette.

Some bike dealer in Wisconsin was selling off a bunch of Trek R200
mid-drives on ebay a while back. Those units had a plain, unramped
cog to drive the rear wheel.

3) Instead of using a rear wheel hub to hold the thing in place you
can use a standard bottom bracket shell (with a freewheel- NOT a
freehub body/cassette). A little known fact is that the threads that
mount a freewheel on a rear hub are exactly the same as the threads in
a BB shell. You can mount a mid-drive by attaching a BB shell to your
frame. Screw a BB end cap part way into the shell, then screw the
freewheel onto the the exposed part of the end cap. Use an alumnum BB
shell instead of a steel one to save a bunch of weight. If you want
to shift gears you'l have to figure out how to mount a derailleur in
the right position, of course.
 
J

Jasper Janssen

Guest
On Tue, 06 Dec 2005 08:55:48 -0600, [email protected] wrote:

>1) The cogs of a typical cassette are designed to be driven and to
>shift easily, not to drive. In order to make this type of mid-drive
>work, you must restack the cogs, with the one that drives the rear
>wheel flipped over (that means about 3 minutes of work with a hand
>file to make it fit back on the free-hub body). If you don't flip the
>rear wheel drive cog, you'll find as I did, that when you pedal hard
>the rear chain will just slip over the teeth of the drive cog.


Shimano makes full-teeth cogs for their BMX cassette hub that are not
shifter-designed but will fit standard Shimano cassette hub splines.
Available IIRC in something like 14/15/16/18 or so, at $5 each from
Harris. If you're not looking for a huge gear ratio, it may be an option,
or you could at least use it on one of the two cogs.

Jasper