Expanding gear ratio on 3-speed hub?

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Date: 06 Jun 2007 00:59:18
From: dabac
Subject: Expanding gear ratio on 3-speed hub?

Hi guys,

I'm a bit tempted to use a composite('similar to the 24\" Tuff wheel H
spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
rear wheel for a commuter bike, but unfortunately the ones most readily
available tend to come with a 3-speed Torpedo hub and I'd like a wider
range to choose from.
I can probably manage the mechanics of it(I've got a welder and a
lathe), but I'm quite clueless about the consequences of messing around
with the gearing of a 3-speed hub. Adding a derailleur and a few
sprockets to the rear would probably be doable, but what teeth numbers
to use in order not to end up duplicating the gearing already available
internally?

And in what sequence would one use with such a frankenhub to get a
steady increment in gearing? Would one run through all external gears
before gearing up internally, or would one go through all internal
first before gearing up externally, or would a gradual increase require
alternate gear changes?

--
dabac

Date: 12 Jun 2007 10:55:16
From: meb
Subject: Re: Expanding gear ratio on 3-speed hub?

dabac Wrote:
> Hi guys,
>
> I'm a bit tempted to use a composite('similar to the 24\" Tuff wheel H
> spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
> rear wheel for a commuter bike, but unfortunately the ones most readily
> available tend to come with a 3-speed Torpedo hub and I'd like a wider
> range to choose from.
> I can probably manage the mechanics of it(I've got a welder and a
> lathe), but I'm quite clueless about the consequences of messing around
> with the gearing of a 3-speed hub. Adding a derailleur and a few
> sprockets to the rear would probably be doable, but what teeth numbers
> to use in order not to end up duplicating the gearing already available
> internally?
>
> And in what sequence would one use with such a frankenhub to get a
> steady increment in gearing? Would one run through all external gears
> before gearing up internally, or would one go through all internal
> first before gearing up externally, or would a gradual increase require
> alternate gear changes?

Not sure if this would work with 3 speed hub and if so which ones:

http://cgi.ebay.com/Old-School-BMX-Vintage-NOS-JB-Freewheel-Adapter-Shimano_W0QQitemZ190122131766QQihZ009QQcategoryZ64644QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

--
meb

Date: 07 Jun 2007 17:23:22
From: Johnny Sunset
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 7, 12:32 pm, Chalo Colina wrote:
> Bill wrote:
>
> > I wonder if anyone will take this to the point of absurdity and try to
> > mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
> > 240 ratios anyone?
>
> Utmost absurdity would be mounting triple rings to a Schlumpf crank,
> with a 10-speed cluster attached to a 14-speed Rohloff hub. 840
> ratios total, with many redundancies. Drivetrain losses would be
> significant.

Chalo's idea would be relatively easy to set-up on this bike: <http://
mnhpva.org/Mini_Bents/pursuit.jpg >.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Date: 07 Jun 2007 18:16:53
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

Johnny Sunset wrote:
> On Jun 7, 12:32 pm, Chalo Colina wrote:
>> Bill wrote:
>>
>>> I wonder if anyone will take this to the point of absurdity and try to
>>> mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
>>> 240 ratios anyone?
>> Utmost absurdity would be mounting triple rings to a Schlumpf crank,
>> with a 10-speed cluster attached to a 14-speed Rohloff hub. 840
>> ratios total, with many redundancies. Drivetrain losses would be
>> significant.
>
> Chalo's idea would be relatively easy to set-up on this bike: <http://
> mnhpva.org/Mini_Bents/pursuit.jpg>.
>
> --
> Tom Sherman - Holstein-Friesland Bovinia
> The weather is here, wish you were beautiful
>
>
>
At least that is not an **uglycycle**.
A triple up front would make a good start.
Bill Baka

Date: 07 Jun 2007 19:32:57
From: Chalo
Subject: Re: Expanding gear ratio on 3-speed hub?

dabac wrote:
>
> > If you want more gears on the
> > cheap, use an old rear derailleur as a tensioner along with a front
> > derailleur and a triple crank.
>
> That approach would obviously expand the range, but wouldn't the
> increment from one gear to the next be rather large? I'll readily admit
> my utter lack of experience in this area.

Since you get to pick the gears on the crank, you can choose one of
two basic approaches. You can maximize overall range, which will make
the steps between chainrings approximately the same size as the steps
between gears in the 3-speed hub. Or you can abbreviate the steps
between rings in order to gain ratios in between and slightly beyond
what your 3-speed offers.

The ratios in a three-speed hub correspond (more or less) to the
intervals between chainrings of 30-40-53 tooth sizes-- pretty close to
a current road triple. If you added such a crank to a three-speed
rear hub, you'd gain another pair of ratios above and below the range
offered by the hub in the same 3:4 step size. That would make your
low/low and your high/high gears new options, but all the others would
be redundant. The resulting overall range would be over 3:1, about
the same as an 11-34 cluster, a SRAM Spectro 7, a Sturmey Archer 8, or
a Shimano Nexus 8. You'd only have 5 meaningfully different ratios
(jumps are large from gear to gear), but you wouldn't have to worry
about shift sequence.

Another way to go would be to use rings that have approximately
0.866:1 ratios between them, for example 33-38-44. That would put the
shifts on the rings right in the middle of the steps between internal
gears. In this case, some of the "between" gears would still be
redundant, for instance middle hub/large ring would be about the same
as high hub/small ring. The overall range would be approximately
2.35:1. You'd have 7 meaningfully different gears.

To have a range of all discrete, non-redundant ratios, use rings that
have approximately 0.91:1 ratios, for example 40-44-48. That would
get you two basically uniform steps between each of the internal gear
ratios, for 9 different gears. Overall, the range would be in the
vicinity of 2.15:1. Shifting sequence is important with this
configuration, but simple: You work your way up the rings, then shift
up on the hub while jumping all the way back down on the rings to get
the next ratio. Steps between gears with this arrangement are nice
and small, but at the expense of overall range.

Chalo

Date: 07 Jun 2007 10:48:18
From: JennyB
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 7, 10:53 am, dabac <dabac.2rs...@no-
mx.forums.cyclingforums.com > wrote:
> Chalo Wrote:

> > If you want more gears on the
> > cheap, use an old rear derailleur as a tensioner along with a front
> > derailleur and a triple crank.
>
> That approach would obviously expand the range, but wouldn't the
> increment from one gear to the next be rather large? I'll readily admit
> my utter lack of experience in this area.
>
Try experimenting with Sheldon's Gear Ratio Calculator
http://www.sheldonbrown.com/gears/

You should try to arrange that for the most useful gears a change of
rings will produce a gear halfway beteween those on the hub. That
means sometimes changing both on the ring and the hub to get the
'next' gear.

Simplest is "half-step" gearing with two close rings - say 36 and 40.
That only extends the range a little, but gives six evenly-spaced
gears.

Or you could use chainrings where the difference is one-and-a-half
time that of the hub gears, say 46 and 28, which would give a range of
89"-29" on a standard 19 tooth sprocket. The changing sequence is a
little more complex - you have 4 evenly-spaced gears, plus a crawler
gear and an overdrive.

Date: 04 Jul 2007 21:37:52
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

JennyB Wrote:
>
> Try experimenting with Sheldon's Gear Ratio Calculator
> http://www.sheldonbrown.com/gears/

I've done that now, and things aren't looking so peachy. I started b
entering the values for my roadied-up MTB as a reference. But even if
leave the granny gear out of it, assume a triple front and that an
chainring I think of is actually available it's still hard to come u
with a combo that both have a comparable span AND ah high number o
useful gears.

Maybe I'll be better off looking at the home-forged cassette again..

--
dabac

Date: 04 Jul 2007 09:59:46
From: Tim McNamara
Subject: Re: Expanding gear ratio on 3-speed hub?

In article <dabac.2t72zb@no-mx.forums.cyclingforums.com >,
dabac <dabac.2t72zb@no-mx.forums.cyclingforums.com > wrote:

> JennyB Wrote:
> >
> > Try experimenting with Sheldon's Gear Ratio Calculator
> > http://www.sheldonbrown.com/gears/
>
> I've done that now, and things aren't looking so peachy. I started by
> entering the values for my roadied-up MTB as a reference. But even if
> I leave the granny gear out of it, assume a triple front and that any
> chainring I think of is actually available it's still hard to come up
> with a combo that both have a comparable span AND ah high number of
> useful gears.
>
> Maybe I'll be better off looking at the home-forged cassette again...

Or you could use the Sachs 3 x 7 or the Sachs/Sram 3 x 8 hub that
combines a 3 speed internally geared hub with a 7 or 8 speed Shimano
compatible cassette.

Date: 05 Jul 2007 19:35:42
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Tim McNamara Wrote:
>
> Or you could use the Sachs 3 x 7 or the Sachs/Sram 3 x 8 hub that
> combines a 3 speed internally geared hub with a 7 or 8 speed Shimano
> compatible cassette.

Thing is, I'm quite set on using these composite wheels that are mainl
available with the basic 3-speed hub. I have no clue as to how the hu
is mated to the wheel, if it's possible to remove the old hub an
transplant a new or not.
If a transplant IS possible I have some mid-range Shimano stuff that
could use already.
So, while waiting for the right opportunity to buy those wheels I'
researching the options that *I know * are open to me, i.e. how t
expand the ratio of a 3-speed hub.
Would a freewheel be likely to be possible to attach where the ordinar
single sprocket sits today

--
dabac

Date: 07 Jun 2007 17:32:48
From: Chalo
Subject: Re: Expanding gear ratio on 3-speed hub?

Bill wrote:
>
> I wonder if anyone will take this to the point of absurdity and try to
> mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
> 240 ratios anyone?

Utmost absurdity would be mounting triple rings to a Schlumpf crank,
with a 10-speed cluster attached to a 14-speed Rohloff hub. 840
ratios total, with many redundancies. Drivetrain losses would be
significant.

Chalo

Date: 07 Jun 2007 18:10:57
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

Chalo wrote:
> Bill wrote:
>> I wonder if anyone will take this to the point of absurdity and try to
>> mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
>> 240 ratios anyone?
>
> Utmost absurdity would be mounting triple rings to a Schlumpf crank,
> with a 10-speed cluster attached to a 14-speed Rohloff hub. 840
> ratios total, with many redundancies. Drivetrain losses would be
> significant.
>
> Chalo
>
Whoa.
I'm almost sorry I mentioned it. I guess that would give a super-ultra
granny as well as a super high top gear.
That would be good for a brain freeze trying to figure out what to shift.
Bill Baka

Date: 07 Jun 2007 17:27:27
From: Chalo
Subject: Re: Expanding gear ratio on 3-speed hub?

Date: 08 Jun 2007 17:26:35
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Chalo Wrote:
>
> Since you get to pick the gears on the crank, you can choose one of
> two basic approaches. ..
> The ratios in a three-speed hub correspond (more or less) to the
> intervals between chainrings of 30-40-53 tooth sizes-- ....
>
> Another way to go would be to use rings that have approximately
> 0.866:1 ratios between them,..You'd have 7 meaningfully differen
> gears.
>
> To have a range of all discrete, non-redundant ratios, use rings that
> have approximately 0.91:1 ratios, ..Steps between gears with thi
> arrangement are nice
> and small, but at the expense of overall range.

This is great stuff, just what I was looking for, thanks! (listen clos
and you'll hear the printer buzzing...)

>
> I'm curious what the 27" 3-speed composite wheel is that you are
> thinking about using, and where you intend to get one.

Behold the Itera, the plastic bike:

[image
http://img.photobucket.com/albums/v633/dabac/bikes/itera-2.jpg]

A perfect example of clueless engineering consistently applied wit
total disregard for material properties.

Taken as a whole the bike is so flexy to be next to unrideable(an
heavy to boot), but stick the wheels in an ordinary frame (or eve
better, one of those old super-stiff over sized aluminum frames) an
suddenly you have a rather nice commuter combo. The composite wheel
offer good braking in the wet, cushions the ride, don't corrode o
oxidize and are very resilient to abuse.

There was a 10-speed version of it, but that was limited edition onl
and quite rare. The 3-speed version was a lot more common and the loca
ebay-equivalent always have a couple for sale for 70-150 USD

--
dabac

Date: 08 Jun 2007 17:41:05
From: Chalo
Subject: Re: Expanding gear ratio on 3-speed hub?

dabac wrote:
>
> Behold the Itera, the plastic bike:
>
> [image:http://img.photobucket.com/albums/v633/dabac/bikes/itera-2.jpg]
>
> A perfect example of clueless engineering consistently applied with
> total disregard for material properties.

Wow. I'd seen pictures of them, but I didn't assume there would be
any left.

That's actually sort of cool, in a perverse way. I have had a long
term project of collecting all-plastic parts as I come across them,
with the intention of eventially building as plasticky a bicycle as I
can. I reckoned that some of the parts would have to be plastic-clad
steel, like Shimano Exage cranks and brakes.

It looks like the Itera surpassed the limits of what I assumed would
be possible. Plastic cranks and forks! Oddly prophetic, really.

Chalo

Date: 31 Aug 2007 20:28:36
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Chalo Wrote:
> That's actually sort of cool, in a perverse way. I have had a long ter
> project of collecting all-plastic parts as I come across them,
> with the intention of eventially building as plasticky a bicycle as I
> can. I reckoned that some of the parts would have to be plastic-clad
> steel, like Shimano Exage cranks and brakes.
>
> It looks like the Itera surpassed the limits of what I assumed would
> be possible. Plastic cranks and forks! I think they missed the fine line between possible to build an
enjoyable to ride...

I went ahead and bought one of these, and it's really a weird design
The plastic theme is taken to the extreme, with even the chain whee
being non-metallic. The BB is also non-metallic and if you turn th
bike over you can actually see the axle rotate when you turn th
cranks. (OS bearings in the sidewalls of the box-like frame structure)
Front wheel has cartridge bearings. Both fork and rear stays have CLOSE
dropouts, no slots. To remove the front wheel you either pull the axl
clear or you simply spread the fork until the axle is disengaged. Fo
the rear there is no other option than brute force spreading of th
stays to get the wheel out.

Riding the bike is an equally comfortable and scary experience, like
balloon-tired cruiser, only more so.
Braking is impressive, considering the simplicity of the gear, bu
pedalling out of the saddle and particularly steering is pure nightmar
material. If you fake a sudden evasive action you have a VERY visibl
wind-up, or steering delay from when you turn the handlebars to whe
the front wheel is actually pointing in a new direction. There's n
trouble at all to see the whole fork/bar assembly twists in action.
If you overcome the scare of the sagging handlebar and insist on doin
some pedalling standing up the next thing you have to face is th
disconcerting feeling of the cranks dipping to the inside at the botto
of each stroke.

Freight across the pond would cost you some, but they really still ar
quite available over here.

Turned out the the 3-speed hubs were Sturmey-Archer, not Sachs-Torped
and by the looks of it they're simply pressed into the hub from th
right side.
I'm having a hard time deciding whether to use the wheel as it is or t
have a go at replacing it with something that would take an ordinar
Shimano body and cassette. Replacement would make for a more versatil
finished bike, unless disassembly turns destructive..

--
dabac

Date: 09 Jun 2007 05:59:11
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Chalo Wrote:
>
>
> Wow. I'd seen pictures of them, but I didn't assume there would be
> any left.

Well, I haven't bought one yet, so I can't vouch for thei
availability, but I see them auctioned/advertised often enough.
Chalo Wrote:
>
> It looks like the Itera surpassed the limits of what I assumed would
> be possible. Plastic cranks and forks!
The one in the pic is actually a 2nd generation standard version. Th
1st gen. also featured plastic handlebars. Not round or anythin
simple like that, but a pair of box-section high-risers. They were ope
from below so that one could see the "honeycomb" (cantilevered, trussed
lots of diagonally braced squares)structure. A highly touted but od
feature was that the flat top of the handlebar could be used as
writing surface and it even came with a hole to stick the pencil in
You had to provide the eraser yourself though...

If you hade one of those you'd better get all thoughts of riding out o
the saddle out of your mind..

--
dabac

Date: 07 Jun 2007 03:45:35
From: Johnny Sunset
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 7, 1:06 am, Bill <b...@comcast.net > wrote:
> Johnny Sunset wrote:
> >
> > I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direct drive
> > and 1.36:1 overdrive.
>
> Those 2 numbers are reciprocals of each other like I expected so that
> would mean 1 planetary gear being used for everything but reverse.

Reverse? Every Sachs Torpedo 3-speed (the basis of the Sachs/SRAM 3x7)
and SRAM DualDrive hub is freewheeling, without a reverse gear.

> > The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
> > with any Sachs Torpedo 3-speed compatible shifter. These were sold for
> > many years as trigger shifters, but SRAM also sold a twist-grip
> > version.
>
> > The newer DualDrive has a combined rear derailleur/hub gear shifter
> > for flat bars, leaving the left handlebar free for a front chainring
> > shifter (if so desired).
>
> > I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hub adds 6
> > useful ratios (3 at each end of the range) and about 36 near duplicate
> > ratios. I doubt the 3x7 in combination with triple chainrings would be
> > worthwhile for most uprights (other than the novelty factor), but the
> > extra ratios are quite useful on a heavy but aerodynamic bicycle such
> > as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm>.
>
> Could be fun just for the stare factor.

Well, on my bike the 3x7 hub is the last thing people notice.

It should be noted that the SRAM DualDrive has different internals
than the old Sachs Torpedo, and shifts better under load. As far as I
am aware, there have been no reports of the DualDrive going into
"false neutral" the way the Sturmey-Archer AW is claimed to under
heavy load.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Date: 07 Jun 2007 16:17:50
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

Johnny Sunset wrote:
> On Jun 7, 1:06 am, Bill <b...@comcast.net> wrote:
>> Johnny Sunset wrote:
>>> I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direct drive
>>> and 1.36:1 overdrive.
>> Those 2 numbers are reciprocals of each other like I expected so that
>> would mean 1 planetary gear being used for everything but reverse.
>
> Reverse? Every Sachs Torpedo 3-speed (the basis of the Sachs/SRAM 3x7)
> and SRAM DualDrive hub is freewheeling, without a reverse gear.

I only mentioned reverse because cars use the same gear set for reverse.
There are quite a lot of combinations that can be done with one
planetary gear cluster.
>
>>> The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
>>> with any Sachs Torpedo 3-speed compatible shifter. These were sold for
>>> many years as trigger shifters, but SRAM also sold a twist-grip
>>> version.
>>> The newer DualDrive has a combined rear derailleur/hub gear shifter
>>> for flat bars, leaving the left handlebar free for a front chainring
>>> shifter (if so desired).
>>> I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hub adds 6
>>> useful ratios (3 at each end of the range) and about 36 near duplicate
>>> ratios. I doubt the 3x7 in combination with triple chainrings would be
>>> worthwhile for most uprights (other than the novelty factor), but the
>>> extra ratios are quite useful on a heavy but aerodynamic bicycle such
>>> as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm>.
>> Could be fun just for the stare factor.
>
> Well, on my bike the 3x7 hub is the last thing people notice.
>
> It should be noted that the SRAM DualDrive has different internals
> than the old Sachs Torpedo, and shifts better under load. As far as I
> am aware, there have been no reports of the DualDrive going into
> "false neutral" the way the Sturmey-Archer AW is claimed to under
> heavy load.
>
> --
> Tom Sherman - Holstein-Friesland Bovinia
> The weather is here, wish you were beautiful
>
I wonder if anyone will take this to the point of absurdity and try to
mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
240 ratios anyone?
Bill Baka

Date: 08 Jun 2007 09:29:10
From: meb
Subject: Re: Expanding gear ratio on 3-speed hub?

Bill Wrote:
> Johnny Sunset wrote:
> > On Jun 7, 1:06 am, Bill <b...@comcast.net> wrote:
> >> Johnny Sunset wrote:
> >>> I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direc
> drive
> >>> and 1.36:1 overdrive.
> >> Those 2 numbers are reciprocals of each other like I expected s
> that
> >> would mean 1 planetary gear being used for everything but reverse.
> >
> > Reverse? Every Sachs Torpedo 3-speed (the basis of the Sachs/SRA
> 3x7)
> > and SRAM DualDrive hub is freewheeling, without a reverse gear.
>
> I only mentioned reverse because cars use the same gear set fo
> reverse.
> There are quite a lot of combinations that can be done with one
> planetary gear cluster.
> >
> >>> The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
> >>> with any Sachs Torpedo 3-speed compatible shifter. These were sol
> for
> >>> many years as trigger shifters, but SRAM also sold a twist-grip
> >>> version.
> >>> The newer DualDrive has a combined rear derailleur/hub gea
> shifter
> >>> for flat bars, leaving the left handlebar free for a fron
> chainring
> >>> shifter (if so desired).
> >>> I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hu
> adds 6
> >>> useful ratios (3 at each end of the range) and about 36 nea
> duplicate
> >>> ratios. I doubt the 3x7 in combination with triple chainrings woul
> be
> >>> worthwhile for most uprights (other than the novelty factor), bu
> the
> >>> extra ratios are quite useful on a heavy but aerodynamic bicycl
> such
> >>> as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm>.
> >> Could be fun just for the stare factor.
> >
> > Well, on my bike the 3x7 hub is the last thing people notice.
> >
> > It should be noted that the SRAM DualDrive has different internals
> > than the old Sachs Torpedo, and shifts better under load. As far a
> I
> > am aware, there have been no reports of the DualDrive going into
> > "false neutral" the way the Sturmey-Archer AW is claimed to under
> > heavy load.
> >
> > --
> > Tom Sherman - Holstein-Friesland Bovinia
> > The weather is here, wish you were beautiful
> >
> I wonder if anyone will take this to the point of absurdity and try to
> mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
> 240 ratios anyone?
> Bill Baka

I have a 42 speed on one of my recumbents, Sachs 3x7 and 53 and 4
front ring.

Queztel, a Canadian recumbent manufacturer (I think they may hav
recently gone out of business) has a 105 speed bike using a middriv
and conventional front and rear ders.

However, Guinness recordholder Leon Chassman has the hypo you propos
beat more than sixfold:

http://www.popularmechanics.com/technology/industry/1284291.htm

--
meb

Date: 07 Jun 2007 18:13:52
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

meb wrote:
> Bill Wrote:
>> Johnny Sunset wrote:
>>> On Jun 7, 1:06 am, Bill <b...@comcast.net> wrote:
>>>> Johnny Sunset wrote:
>>>>> I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direct
>> drive
>>>>> and 1.36:1 overdrive.
>>>> Those 2 numbers are reciprocals of each other like I expected so
>> that
>>>> would mean 1 planetary gear being used for everything but reverse.
>>> Reverse? Every Sachs Torpedo 3-speed (the basis of the Sachs/SRAM
>> 3x7)
>>> and SRAM DualDrive hub is freewheeling, without a reverse gear.
>> I only mentioned reverse because cars use the same gear set for
>> reverse.
>> There are quite a lot of combinations that can be done with one
>> planetary gear cluster.
>>>>> The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
>>>>> with any Sachs Torpedo 3-speed compatible shifter. These were sold
>> for
>>>>> many years as trigger shifters, but SRAM also sold a twist-grip
>>>>> version.
>>>>> The newer DualDrive has a combined rear derailleur/hub gear
>> shifter
>>>>> for flat bars, leaving the left handlebar free for a front
>> chainring
>>>>> shifter (if so desired).
>>>>> I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hub
>> adds 6
>>>>> useful ratios (3 at each end of the range) and about 36 near
>> duplicate
>>>>> ratios. I doubt the 3x7 in combination with triple chainrings would
>> be
>>>>> worthwhile for most uprights (other than the novelty factor), but
>> the
>>>>> extra ratios are quite useful on a heavy but aerodynamic bicycle
>> such
>>>>> as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm>.
>>>> Could be fun just for the stare factor.
>>> Well, on my bike the 3x7 hub is the last thing people notice.
>>>
>>> It should be noted that the SRAM DualDrive has different internals
>>> than the old Sachs Torpedo, and shifts better under load. As far as
>> I
>>> am aware, there have been no reports of the DualDrive going into
>>> "false neutral" the way the Sturmey-Archer AW is claimed to under
>>> heavy load.
>>>
>>> --
>>> Tom Sherman - Holstein-Friesland Bovinia
>>> The weather is here, wish you were beautiful
>>>
>> I wonder if anyone will take this to the point of absurdity and try to
>> mate a triple crank, 10 speed cluster, and a 7 or 8 speed hub. 210 or
>> 240 ratios anyone?
>> Bill Baka
>
> I have a 42 speed on one of my recumbents, Sachs 3x7 and 53 and 42
> front ring.
>
> Queztel, a Canadian recumbent manufacturer (I think they may have
> recently gone out of business) has a 105 speed bike using a middrive
> and conventional front and rear ders.
>
> However, Guinness recordholder Leon Chassman has the hypo you propose
> beat more than sixfold:
>
>
> http://www.popularmechanics.com/technology/industry/1284291.html
>
>
I concede. Even Rube Goldberg would do a double take on that one.
It looks ugly in the picture though, like maybe add some chrome..?
Bill Baka

Date: 07 Jun 2007 18:13:14
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

Date: 06 Jun 2007 22:09:13
From: JeffWills
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 6, 6:17 am, wantzeliusp <paul.o.wantzel...@boeing.com > wrote:
> I was not aware of this model; it's not the same model I was thinking
> of. This one requires a special shifter and derailleur to work. The
> older model works with any standard shifter and derailleur. But it does
> indeed consist of a 3-speed hub with a cassette.
>

Not true. The 3x8/3x9 hub accepts a standard SRAM cassette, which is
to say it will take any 8- or 9-speed Shimano Hyperglide-style
cassette. The derailleur can be a standard SRAM or Shimano unit, and
the shifter only has to match the derailleur. The only "special"
shifter is the 3-speed unit that operates the Clickbox.

Jeff

Date: 07 Jun 2007 02:57:33
From: mike.a.schwab@gmail.com
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 6, 9:17 am, wantzeliusp <paul.o.wantzel...@boeing.com > wrote:
> I was not aware of this model; it's not the same model I was thinking
> of. This one requires a special shifter and derailleur to work. The
> older model works with any standard shifter and derailleur. But it does
> indeed consist of a 3-speed hub with a cassette.
>
> Marcus Coles wrote:
>
> > Dane Buson wrote:
> > > wantzeliusp <paul.o.wantzel...@boeing.com> wrote:
> > >> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
> > >> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
> > >> can probably find one somewhere (Ebay??)
>
> > > Are you sure they're not produced anymore? I've seen them recently on sale.
>
> > >http://www.universalcycles.com/shopping/index.php?category=2713
> > >http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
> > >http://www.sheldonbrown.com/harris/sram.html
>
> > Yes, they are in their comfort bike range of components called
> > "Dual Drive II" 3x8 and 3x9 these days.
>
> >http://www.sram.com

My LBS had one from a broken wheel, I had them put on a 20 inch rim
for my EZ-1 and a thumb shifter. Now I have a 3*3*7 63 speed. But I
always use the middle hub gear except for hills when I get to the
bottom of the ring and cog. When I hit the top of the ring and cog
and try the high hub gear, I slow down about 15% due to the
inefficiency.

Date: 06 Jun 2007 18:40:00
From: Johnny Sunset
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 5, 9:59 am, "dabac" wrote:
> Hi guys,
>
> I'm a bit tempted to use a composite('similar to the 24\" Tuff wheel H
> spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
> rear wheel for a commuter bike,...

Are the spokes pre-tensioned or pre-compressed?

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Date: 07 Jun 2007 19:35:57
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Johnny Sunset Wrote:
> On Jun 5, 9:59 am, "dabac" wrote:
> > Hi guys,
> >
> > I'm a bit tempted to use a composite('similar to the 24\" Tuff whee
> H
> > spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
> > rear wheel for a commuter bike,...
>
> Are the spokes pre-tensioned or pre-compressed?

The only things I feel confident in stating with certainty is that the
come pre-assembled (and in my case, pre-owned...

--
dabac

Date: 06 Jun 2007 18:37:33
From: Johnny Sunset
Subject: Re: Expanding gear ratio on 3-speed hub?

On Jun 6, 2:02 pm, Bill Baka wrote:
> wantzeliusp wrote:
> > I was not aware of this model; it's not the same model I was thinking
> > of. This one requires a special shifter and derailleur to work. The
> > older model works with any standard shifter and derailleur. But it does
> > indeed consist of a 3-speed hub with a cassette.
>
> > Marcus Coles wrote:
> >> Dane Buson wrote:
> >>> wantzeliusp <paul.o.wantzel...@boeing.com> wrote:
> >>>> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
> >>>> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
> >>>> can probably find one somewhere (Ebay??)
> >>> Are you sure they're not produced anymore? I've seen them recently on sale.
>
> >>>http://www.universalcycles.com/shopping/index.php?category=2713
> >>>http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
> >>>http://www.sheldonbrown.com/harris/sram.html
>
> >> Yes, they are in their comfort bike range of components called
> >> "Dual Drive II" 3x8 and 3x9 these days.
>
> >>http://www.sram.com
>
> Neat stuff. A bit pricey but still would be a great conversation
> starter. I'm wondering how well they might hold up for climbing with a
> 30/28 combo or if they would help on a downhill where you are already in
> a 52/11. Too bad I didn't find the ratios listed.
> I can envision a whole Saturday devoted to lacing a wheel and truing it,
> then taking a just before sunset test ride.
> Good stuff still exists.
> Yeah.

I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direct drive
and 1.36:1 overdrive.

The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
with any Sachs Torpedo 3-speed compatible shifter. These were sold for
many years as trigger shifters, but SRAM also sold a twist-grip
version.

The newer DualDrive has a combined rear derailleur/hub gear shifter
for flat bars, leaving the left handlebar free for a front chainring
shifter (if so desired).

I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hub adds 6
useful ratios (3 at each end of the range) and about 36 near duplicate
ratios. I doubt the 3x7 in combination with triple chainrings would be
worthwhile for most uprights (other than the novelty factor), but the
extra ratios are quite useful on a heavy but aerodynamic bicycle such
as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm >.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Date: 07 Jun 2007 06:06:24
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

Johnny Sunset wrote:
> On Jun 6, 2:02 pm, Bill Baka wrote:
>> wantzeliusp wrote:
>>> I was not aware of this model; it's not the same model I was thinking
>>> of. This one requires a special shifter and derailleur to work. The
>>> older model works with any standard shifter and derailleur. But it does
>>> indeed consist of a 3-speed hub with a cassette.
>>> Marcus Coles wrote:
>>>> Dane Buson wrote:
>>>>> wantzeliusp <paul.o.wantzel...@boeing.com> wrote:
>>>>>> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
>>>>>> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
>>>>>> can probably find one somewhere (Ebay??)
>>>>> Are you sure they're not produced anymore? I've seen them recently on sale.
>>>>> http://www.universalcycles.com/shopping/index.php?category=2713
>>>>> http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
>>>>> http://www.sheldonbrown.com/harris/sram.html
>>>> Yes, they are in their comfort bike range of components called
>>>> "Dual Drive II" 3x8 and 3x9 these days.
>>>> http://www.sram.com
>> Neat stuff. A bit pricey but still would be a great conversation
>> starter. I'm wondering how well they might hold up for climbing with a
>> 30/28 combo or if they would help on a downhill where you are already in
>> a 52/11. Too bad I didn't find the ratios listed.
>> I can envision a whole Saturday devoted to lacing a wheel and truing it,
>> then taking a just before sunset test ride.
>> Good stuff still exists.
>> Yeah.
>
> I believe the SRAM hub ratios are 0.73:1 underdrive, 1:1 direct drive
> and 1.36:1 overdrive.

Those 2 numbers are reciprocals of each other like I expected so that
would mean 1 planetary gear being used for everything but reverse.
>
> The older Sachs/SRAM Spectro 3x7 hub internal gears can be shifted
> with any Sachs Torpedo 3-speed compatible shifter. These were sold for
> many years as trigger shifters, but SRAM also sold a twist-grip
> version.
>
> The newer DualDrive has a combined rear derailleur/hub gear shifter
> for flat bars, leaving the left handlebar free for a front chainring
> shifter (if so desired).
>
> I have a 63-speed setup with a SRAM 3x7 hub. Basically, the hub adds 6
> useful ratios (3 at each end of the range) and about 36 near duplicate
> ratios. I doubt the 3x7 in combination with triple chainrings would be
> worthwhile for most uprights (other than the novelty factor), but the
> extra ratios are quite useful on a heavy but aerodynamic bicycle such
> as <http://www.ransbikes.com/Gallery/Archive/Sherman.htm>.

Could be fun just for the stare factor.
Bill Baka
>
> --
> Tom Sherman - Holstein-Friesland Bovinia
> The weather is here, wish you were beautiful
>

Date: 06 Jun 2007 19:26:53
From: Chalo
Subject: Re: Expanding gear ratio on 3-speed hub?

dabac wrote:
>
> I'm a bit tempted to use a composite('similar to the 24\" Tuff wheel H
> spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
> rear wheel for a commuter bike, but unfortunately the ones most readily
> available tend to come with a 3-speed Torpedo hub and I'd like a wider
> range to choose from.
> I can probably manage the mechanics of it(I've got a welder and a
> lathe), but I'm quite clueless about the consequences of messing around
> with the gearing of a 3-speed hub. Adding a derailleur and a few
> sprockets to the rear would probably be doable, but what teeth numbers
> to use in order not to end up duplicating the gearing already available
> internally?

My advice? Don't mess with the hub. If you want more gears on the
cheap, use an old rear derailleur as a tensioner along with a front
derailleur and a triple crank. If cost is not an impediment, use a
Schlumpf crank.

Chalo

Date: 07 Jun 2007 19:53:29
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

Chalo Wrote:
>
> My advice? Don't mess with the hub. Quite probably an excellent piece of advice from a strictly practica
standpoint.

Chalo Wrote:
>
> If you want more gears on the
> cheap, use an old rear derailleur as a tensioner along with a front
> derailleur and a triple crank.

That approach would obviously expand the range, but wouldn't th
increment from one gear to the next be rather large? I'll readily admi
my utter lack of experience in this area.

Chalo Wrote:
>
> If cost is not an impediment, use a
> Schlumpf crank.

Cost is a so-so issue. First I don't really know if either my dail
schedule or my knees will stand up to the commute I've been thinkin
about. Secondly it's also about the fun and the challenge of the build
I'd be more open to the suggestion of a Schlumpf if I felt more certai
about the final outcome of this idea

--
dabac

Date: 08 Jun 2007 09:41:47
From: meb
Subject: Re: Expanding gear ratio on 3-speed hub?

dabac Wrote:
> Quite probably an excellent piece of advice from a strictly practica
> standpoint.
>
>
>
> That approach would obviously expand the range, but wouldn't th
> increment from one gear to the next be rather large? I'll readily admi
> my utter lack of experience in this area.
>
>
>
> Cost is a so-so issue. First I don't really know if either my dail
> schedule or my knees will stand up to the commute I've been thinkin
> about. Secondly it's also about the fun and the challenge of the build
> I'd be more open to the suggestion of a Schlumpf if I felt more certai
> about the final outcome of this idea.

The Schlumpf mountain drive has a 2.5:1 reduction. Not much chance o
duplicate ratios with a 3 speed. If you went to a larger ring, you'
have higher and lower ratios covered. It's a proven approach, s
likelihood of success is not an issue-expense might be.

You could even expand the project later with a front der on th
Schlumpf.

The Schlumpf is the Cadilac approach, the triple front rings Chalo i
the budget approach, or remachined gears is the techno machinis
challenge

--
meb

Date: 04 Jul 2007 20:47:27
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

meb Wrote:
> ..remachined gears is the techno machinist challenge.
I really would love it if I had the machinery or the skills t
manufacture my own cogs for a planetary gear, but that is far beyond m
reach. However, building up a sort of body by sticking a few extr
sprockets on to the existing one would be a fairly manageable task

--
dabac

Date: 08 Jun 2007 17:28:27
From: dabac
Subject: Re: Expanding gear ratio on 3-speed hub?

meb Wrote:
>
> The Schlumpf is the Cadilac approach, the triple front rings Chalo i
> the budget approach, or remachined gears is the techno machinis
> challenge.

So many choices, so little need! :

--
dabac

Date: 05 Jun 2007 16:42:45
From: wantzeliusp
Subject: Re: Expanding gear ratio on 3-speed hub?

SRAM used to make a combination of a 3-speed hub that took a 7-speed or
8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
can probably find one somewhere (Ebay??)

I have a bike with one. I use the middle hub gear mostly, changing to
the big or small gear in the hub only when necessary.

dabac wrote:
>
> Hi guys,
>
> I'm a bit tempted to use a composite('similar to the 24\" Tuff wheel H
> spoke but in 27\"' (http://www.skywaywheels.com/products_003.htm))
> rear wheel for a commuter bike, but unfortunately the ones most readily
> available tend to come with a 3-speed Torpedo hub and I'd like a wider
> range to choose from.
> I can probably manage the mechanics of it(I've got a welder and a
> lathe), but I'm quite clueless about the consequences of messing around
> with the gearing of a 3-speed hub. Adding a derailleur and a few
> sprockets to the rear would probably be doable, but what teeth numbers
> to use in order not to end up duplicating the gearing already available
> internally?
>
> And in what sequence would one use with such a frankenhub to get a
> steady increment in gearing? Would one run through all external gears
> before gearing up internally, or would one go through all internal
> first before gearing up externally, or would a gradual increase require
> alternate gear changes?
>
> --
> dabac

Date: 05 Jun 2007 10:10:05
From: Dane Buson
Subject: Re: Expanding gear ratio on 3-speed hub?

wantzeliusp <paul.o.wantzelius@boeing.com > wrote:
> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
> can probably find one somewhere (Ebay??)

Are you sure they're not produced anymore? I've seen them recently on sale.

http://www.universalcycles.com/shopping/index.php?category=2713
http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
http://www.sheldonbrown.com/harris/sram.html

--
Dane Buson - sigdane@unixbigots.org
"I have sworn upon the altar of God eternal hostility against
every form of tyranny over the mind of man."
-Thomas Jefferson-1800 A.D.

Date: 05 Jun 2007 14:39:33
From: Marcus Coles
Subject: Re: Expanding gear ratio on 3-speed hub?

Dane Buson wrote:
> wantzeliusp <paul.o.wantzelius@boeing.com> wrote:
>> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
>> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
>> can probably find one somewhere (Ebay??)
>
> Are you sure they're not produced anymore? I've seen them recently on sale.
>
> http://www.universalcycles.com/shopping/index.php?category=2713
> http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
> http://www.sheldonbrown.com/harris/sram.html
>
Yes, they are in their comfort bike range of components called
"Dual Drive II" 3x8 and 3x9 these days.

http://www.sram.com

Date: 06 Jun 2007 14:17:20
From: wantzeliusp
Subject: Re: Expanding gear ratio on 3-speed hub?

I was not aware of this model; it's not the same model I was thinking
of. This one requires a special shifter and derailleur to work. The
older model works with any standard shifter and derailleur. But it does
indeed consist of a 3-speed hub with a cassette.

Marcus Coles wrote:
>
> Dane Buson wrote:
> > wantzeliusp <paul.o.wantzelius@boeing.com> wrote:
> >> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
> >> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
> >> can probably find one somewhere (Ebay??)
> >
> > Are you sure they're not produced anymore? I've seen them recently on sale.
> >
> > http://www.universalcycles.com/shopping/index.php?category=2713
> > http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
> > http://www.sheldonbrown.com/harris/sram.html
> >
> Yes, they are in their comfort bike range of components called
> "Dual Drive II" 3x8 and 3x9 these days.
>
> http://www.sram.com

Date: 06 Jun 2007 12:02:50
From: Bill
Subject: Re: Expanding gear ratio on 3-speed hub?

wantzeliusp wrote:
> I was not aware of this model; it's not the same model I was thinking
> of. This one requires a special shifter and derailleur to work. The
> older model works with any standard shifter and derailleur. But it does
> indeed consist of a 3-speed hub with a cassette.
>
> Marcus Coles wrote:
>> Dane Buson wrote:
>>> wantzeliusp <paul.o.wantzelius@boeing.com> wrote:
>>>> SRAM used to make a combination of a 3-speed hub that took a 7-speed or
>>>> 8-speed cassette. Called a 3x7 or 3x8 IIRC. Not made anymore but you
>>>> can probably find one somewhere (Ebay??)
>>> Are you sure they're not produced anymore? I've seen them recently on sale.
>>>
>>> http://www.universalcycles.com/shopping/index.php?category=2713
>>> http://aebike.com/page.cfm?action=details&PageID=30&SKU=HU2594
>>> http://www.sheldonbrown.com/harris/sram.html
>>>
>> Yes, they are in their comfort bike range of components called
>> "Dual Drive II" 3x8 and 3x9 these days.
>>
>> http://www.sram.com

Neat stuff. A bit pricey but still would be a great conversation
starter. I'm wondering how well they might hold up for climbing with a
30/28 combo or if they would help on a downhill where you are already in
a 52/11. Too bad I didn't find the ratios listed.
I can envision a whole Saturday devoted to lacing a wheel and truing it,
then taking a just before sunset test ride.
Good stuff still exists.
Yeah.
Bill Baka