interchangeable hubs?

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's. I'm just learning how to maintain and repair my own bike, and
was wondering if it is possible to convert the current Shimano 3-speed
hub to one of their new Nexus 7-speed hubs. Where would I start to
figure out if it's even possible? (Tire size, frame fork, something
else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

In article
<[email hidden]>,

landotter said:

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's. I'm just learning how to maintain and repair my own bike, and
was wondering if it is possible to convert the current Shimano 3-speed
hub to one of their new Nexus 7-speed hubs. Where would I start to
figure out if it's even possible? (Tire size, frame fork, something
else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

The Nexus 7 hubs can be built with rim, roller, or coaster brake setups,
so you can preserve the present braking setup or change it as you prefer.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have. I doubt you'll notice,
and if you might, you'll probably want one of the even spiffier 8-speed
Nexus/Alfine hubs, or the also-spiffy SRAM iMotion 9 hub.

For any of those not-Sturmey hubs, respacing is a mildly unusual
mechanical challenge that will require either an enthusiastic amateur or
a mostly-competent LBS.

If you're taking a DIY approach, you'll need a new rear wheel, spec the
brake properly, a new shifter, and the various small parts. Plus you'll
need to re-space the frame if you don't go for the S-A 7.

Dealing with a shop that has done such a conversion before will help you
avoid one of my minor mistakes: if you order, for example, an Alfine
hub, the standard Shimano part number (at least around here) gets you a
bare hub, but no shifter or cabling (they come together as a separate
part number), no cog (your old 3-speed cog will work fine,
surprisingly), and no cable attachment thingy, magic lockring thingy, or
anti-turn nuts (again, the distributors in my country pack those three
pieces into a different part number).

Logically ordering just the shifter and the hub will get you a set of
elegant-looking mechanical lumps and a bit of research and waiting to
find the complete finishing bits.

I'd like to thank Dan Burkhart of Boomer Cycle (Ontario) for helping out
with that part. In the US, Harris Cyclery is the canonical source
knowledge and hubs-in-stock, and their prices are a benchmark, if a
beatable one.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

Ryan Cousineau said:

In article
<[email hidden]>,

landotter said:

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's.  I'm just learning how to maintain and repair my own bike, and
was wondering if it is possible to convert the current Shimano 3-speed
hub to one of their new Nexus 7-speed hubs.  Where would I start to
figure out if it's even possible?  (Tire size, frame fork, something
else?)

Quoted message said:

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

To elaborate tangentially from there, the rim is likely an "26 x 1
3/8" EA3 size, or 590mm, which is right inbetween "road" and "mtb"
size wheels. A common and good version is the Sun Cr-18. It's polished
aluminum, and looks great on restored rides:
http://www.bikemannetwork.com/biking/p/RM8494

27" rims are also readily available.

If you're super lucky, though, and the bike is an actual mtb size
26" (559mm), then you can purchase a pre-built Nexus wheel for less
than the sum of the parts.

One last thing to consider if you want retro with zero work, you can
get the really cool Schwinn "Coffee" for $250 in a single speed, and
the three speed retails for around $370. Checked one out at my LBS.
Looks retro from a distance, but rides like a modern bike. Sweet!

http://bikesfortherestofus.blogspot.com/2008/02/schwinn-coffee-cruiser.html

Ryan Cousineau said:

In article
<[email hidden]>,

landotter said:

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's. I'm just learning how to maintain and repair my own bike,
and was wondering if it is possible to convert the current Shimano
3-speed hub to one of their new Nexus 7-speed hubs. Where would I
start to figure out if it's even possible? (Tire size, frame fork,
something else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

The Nexus 7 hubs can be built with rim, roller, or coaster brake setups,
so you can preserve the present braking setup or change it as you
prefer.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have.

Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
not be a good choice for the OP because the gearing is better suited to
small-wheeled bikes:

http://sheldonbrown.com/harris/sturmey-archer-hubs.html

Quoted message said:

I doubt you'll notice,
and if you might, you'll probably want one of the even spiffier 8-speed
Nexus/Alfine hubs, or the also-spiffy SRAM iMotion 9 hub.

For any of those not-Sturmey hubs, respacing is a mildly unusual
mechanical challenge that will require either an enthusiastic amateur or
a mostly-competent LBS.

If you're taking a DIY approach, you'll need a new rear wheel, spec the
brake properly, a new shifter, and the various small parts. Plus you'll
need to re-space the frame if you don't go for the S-A 7.

Dealing with a shop that has done such a conversion before will help you
avoid one of my minor mistakes: if you order, for example, an Alfine
hub, the standard Shimano part number (at least around here) gets you a
bare hub, but no shifter or cabling (they come together as a separate
part number), no cog (your old 3-speed cog will work fine,
surprisingly), and no cable attachment thingy, magic lockring thingy, or
anti-turn nuts (again, the distributors in my country pack those three
pieces into a different part number).

Logically ordering just the shifter and the hub will get you a set of
elegant-looking mechanical lumps and a bit of research and waiting to
find the complete finishing bits.

I'd like to thank Dan Burkhart of Boomer Cycle (Ontario) for helping out
with that part. In the US, Harris Cyclery is the canonical source
knowledge and hubs-in-stock, and their prices are a benchmark, if a
beatable one.

In article
<[email hidden]>,

landotter said:

One last thing to consider if you want retro with zero work, you can
get the really cool Schwinn "Coffee" for $250 in a single speed, and
the three speed retails for around $370. Checked one out at my LBS.
Looks retro from a distance, but rides like a modern bike. Sweet!

http://bikesfortherestofus.blogspot.com/2008/02/schwinn-coffee-cruiser.html

That is a gracefully retro bike!

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

In article <[email hidden]>,

Gary Young said:

Ryan Cousineau said:

In article
<[email hidden]>,

landotter said:

On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
> I have an old huffy 3-speed, my best guess is that it is from the
> 1970's. I'm just learning how to maintain and repair my own bike,
> and was wondering if it is possible to convert the current Shimano
> 3-speed hub to one of their new Nexus 7-speed hubs. Where would I
> start to figure out if it's even possible? (Tire size, frame fork,
> something else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have.

Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
not be a good choice for the OP because the gearing is better suited to
small-wheeled bikes:

http://sheldonbrown.com/harris/sturmey-archer-hubs.html

Argh yes, that's the one. My excuse is that they used to make a 7-speed.
Or perhaps I'm just going senile.

Nonetheless, while you're roughly right about the gearing (it's really
just a matter of the direct-drive gear being the lowest gear; not a
fatal issue), the hub's claim to fame is that it can be put into a frame
as narrow as 115 mm.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's. I'm just learning how to maintain and repair my own bike, and
was wondering if it is possible to convert the current Shimano 3-speed
hub to one of their new Nexus 7-speed hubs. Where would I start to
figure out if it's even possible? (Tire size, frame fork, something
else?)

A point to consider is that the Nexus hubs have a control-cable arrangement
that runs inside the chainstay, while the SA hubs have the control-cable
running through the axle nut.

This means that you may need an anti-rotation washer for the Nexus
different than what may be supplied, in order to get the control-cable to
run in the direction you wish. These washers have varying degrees of
offset between the axle flats and the dropout tangs; I think they are
available separately, but you may have to look hard.

Gary Young said:

Ryan Cousineau said:

In article
<[email hidden]>,

landotter said:

On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
> I have an old huffy 3-speed, my best guess is that it is from the
> 1970's. I'm just learning how to maintain and repair my own bike,
> and was wondering if it is possible to convert the current Shimano
> 3-speed hub to one of their new Nexus 7-speed hubs. Where would I
> start to figure out if it's even possible? (Tire size, frame fork,
> something else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

The Nexus 7 hubs can be built with rim, roller, or coaster brake setups,
so you can preserve the present braking setup or change it as you
prefer.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have.

Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
not be a good choice for the OP because the gearing is better suited to
small-wheeled bikes:

Nonsense.

The only difference between a small-wheeled version and a large-wheeled
version of a successful Nexus conversion are the sizes of the chainring and
rear cog; the internal arrangements of the gearhub have no increased
suitablilty for wheels of any size. The only considerations of this order
that would be of importance are range of gearing available and maximum
torque allowed.

_ said:

Gary Young said:

Ryan Cousineau said:

In article
<[email hidden]>,
landotter <[email hidden]> wrote:

> On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
> > I have an old huffy 3-speed, my best guess is that it is from the
> > 1970's. I'm just learning how to maintain and repair my own bike,
> > and was wondering if it is possible to convert the current Shimano
> > 3-speed hub to one of their new Nexus 7-speed hubs. Where would I
> > start to figure out if it's even possible? (Tire size, frame fork,
> > something else?)
>
> Sure, it's possible. A Sturmey Archer hub might be a better choice
> for that frame spacing, if you don't want to spread it. Plenty of
> options with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

The Nexus 7 hubs can be built with rim, roller, or coaster brake
setups, so you can preserve the present braking setup or change it as
you prefer.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have.

Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
not be a good choice for the OP because the gearing is better suited to
small-wheeled bikes:

Nonsense.

The only difference between a small-wheeled version and a large-wheeled
version of a successful Nexus conversion are the sizes of the chainring
and rear cog; the internal arrangements of the gearhub have no increased
suitablilty for wheels of any size. The only considerations of this
order that would be of importance are range of gearing available and
maximum torque allowed.

Take a look at Sheldon Brown's internal gear calculator:

http://sheldonbrown.com/gears/internal.html

If the OP has 26-inch wheels, a 170mm crank, and a 40-tooth chainring,
then adding the Sturmey-Archer 8-speed hub with its stock 25-tooth
sprocket would give him a range of 41.6 to 126.9 gear inches. That
strikes me as pretty high for a typical gearhub bike.

Now try the Shimano Nexus 8-speed hub with its stock 19-tooth sprocket
(all else held equal) and you get a range of 28.8 to 88.4 gear inches.

It's true that you could get the Sturmey-Archer down into the Nexus
territory with a 28-tooth chainring, but it's my understanding that such
a small ring would probably result in rapid wear of the ring and chain
(though perhaps I'm mistaken about that). Moreover, the OP, who has an
old 3-speed, probably doesn't have a crank with replaceable rings and
thus would have to buy a new crank and maybe a new bottom bracket.

This problem would be exacerbated if the OP's wheels are larger than 26
inches.

So, I don't think it's nonsense to say that the Sturmey-Archer hub is
better suited to small-wheeled bicycles (and actually I was just echoing
Sheldon Brown's judgment on that).

Gary Young said:

_ said:

Gary Young said:

On Wed, 16 Apr 2008 02:30:10 +0000, Ryan Cousineau wrote:

> In article
> <[email hidden]>,
> landotter <[email hidden]> wrote:
>
>> On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
>> > I have an old huffy 3-speed, my best guess is that it is from the
>> > 1970's. I'm just learning how to maintain and repair my own bike,
>> > and was wondering if it is possible to convert the current Shimano
>> > 3-speed hub to one of their new Nexus 7-speed hubs. Where would I
>> > start to figure out if it's even possible? (Tire size, frame fork,
>> > something else?)
>>
>> Sure, it's possible. A Sturmey Archer hub might be a better choice
>> for that frame spacing, if you don't want to spread it. Plenty of
>> options with and without brakes.
>
> To elaborate, you'll almost certainly want to build a new wheel around
> the Nexus hub, so just find out what the old wheel size was (you can
> easily determine that from the tire markings or by taking it to a
> half-competent LBS), and spec the necessary rim from there.
>
> The Nexus 7 hubs can be built with rim, roller, or coaster brake
> setups, so you can preserve the present braking setup or change it as
> you prefer.
>
> As Landotter suggests, an S-A 7-speed will fit in your frame without
> changing the rear spacing, though potentially at the cost of a bit of
> efficiency and niceness that the Nexus hubs have.

Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
not be a good choice for the OP because the gearing is better suited to
small-wheeled bikes:

Nonsense.

The only difference between a small-wheeled version and a large-wheeled
version of a successful Nexus conversion are the sizes of the chainring
and rear cog; the internal arrangements of the gearhub have no increased
suitablilty for wheels of any size. The only considerations of this
order that would be of importance are range of gearing available and
maximum torque allowed.

Take a look at Sheldon Brown's internal gear calculator:

http://sheldonbrown.com/gears/internal.html

If the OP has 26-inch wheels, a 170mm crank, and a 40-tooth chainring,
then adding the Sturmey-Archer 8-speed hub with its stock 25-tooth
sprocket would give him a range of 41.6 to 126.9 gear inches. That
strikes me as pretty high for a typical gearhub bike.

Now try the Shimano Nexus 8-speed hub with its stock 19-tooth sprocket
(all else held equal) and you get a range of 28.8 to 88.4 gear inches.

It's true that you could get the Sturmey-Archer down into the Nexus
territory with a 28-tooth chainring, but it's my understanding that such
a small ring would probably result in rapid wear of the ring and chain
(though perhaps I'm mistaken about that). Moreover, the OP, who has an
old 3-speed, probably doesn't have a crank with replaceable rings and
thus would have to buy a new crank and maybe a new bottom bracket.

This problem would be exacerbated if the OP's wheels are larger than 26
inches.

So, I don't think it's nonsense to say that the Sturmey-Archer hub is
better suited to small-wheeled bicycles (and actually I was just echoing
Sheldon Brown's judgment on that).

But it is not the HUB that is unsuited to small wheels, it's the rest of
the kit.

(And chain wear is not made worse by small sprockets until you get into the
11-12-13 tooth range; though 11's have been used on SA multi-gear hubs, and
I run a 13 on the Nexus.)

_ said:

Gary Young said:

_ said:

On Tue, 15 Apr 2008 22:22:36 -0500, Gary Young wrote:

> On Wed, 16 Apr 2008 02:30:10 +0000, Ryan Cousineau wrote:
>
>> In article
>> <[email hidden]>,
>> landotter <[email hidden]> wrote:
>>
>>> On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
>>> > I have an old huffy 3-speed, my best guess is that it is from the
>>> > 1970's. I'm just learning how to maintain and repair my own
>>> > bike, and was wondering if it is possible to convert the current
>>> > Shimano 3-speed hub to one of their new Nexus 7-speed hubs.
>>> > Where would I start to figure out if it's even possible? (Tire
>>> > size, frame fork, something else?)
>>>
>>> Sure, it's possible. A Sturmey Archer hub might be a better choice
>>> for that frame spacing, if you don't want to spread it. Plenty of
>>> options with and without brakes.
>>
>> To elaborate, you'll almost certainly want to build a new wheel
>> around the Nexus hub, so just find out what the old wheel size was
>> (you can easily determine that from the tire markings or by taking
>> it to a half-competent LBS), and spec the necessary rim from there.
>>
>> The Nexus 7 hubs can be built with rim, roller, or coaster brake
>> setups, so you can preserve the present braking setup or change it
>> as you prefer.
>>
>> As Landotter suggests, an S-A 7-speed will fit in your frame without
>> changing the rear spacing, though potentially at the cost of a bit
>> of efficiency and niceness that the Nexus hubs have.
>
> Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that
> may not be a good choice for the OP because the gearing is better
> suited to small-wheeled bikes:
>
>
Nonsense.

The only difference between a small-wheeled version and a
large-wheeled version of a successful Nexus conversion are the sizes
of the chainring and rear cog; the internal arrangements of the
gearhub have no increased suitablilty for wheels of any size. The
only considerations of this order that would be of importance are
range of gearing available and maximum torque allowed.

Take a look at Sheldon Brown's internal gear calculator:

http://sheldonbrown.com/gears/internal.html

If the OP has 26-inch wheels, a 170mm crank, and a 40-tooth chainring,
then adding the Sturmey-Archer 8-speed hub with its stock 25-tooth
sprocket would give him a range of 41.6 to 126.9 gear inches. That
strikes me as pretty high for a typical gearhub bike.

Now try the Shimano Nexus 8-speed hub with its stock 19-tooth sprocket
(all else held equal) and you get a range of 28.8 to 88.4 gear inches.

It's true that you could get the Sturmey-Archer down into the Nexus
territory with a 28-tooth chainring, but it's my understanding that
such a small ring would probably result in rapid wear of the ring and
chain (though perhaps I'm mistaken about that). Moreover, the OP, who
has an old 3-speed, probably doesn't have a crank with replaceable
rings and thus would have to buy a new crank and maybe a new bottom
bracket.

This problem would be exacerbated if the OP's wheels are larger than 26
inches.

So, I don't think it's nonsense to say that the Sturmey-Archer hub is
better suited to small-wheeled bicycles (and actually I was just
echoing Sheldon Brown's judgment on that).

But it is not the HUB that is unsuited to small wheels, it's the rest of
the kit.

The OP wants to revamp an old Huffy. I suspect that means he's either not
willing or financially able to swap out his entire kit. Besides, at that
point he would probably be better off buying a new bike.

Quoted message said:

(And chain wear is not made worse by small sprockets until you get into
the 11-12-13 tooth range; though 11's have been used on SA multi-gear
hubs, and I run a 13 on the Nexus.)

The issue is the size of the chainring, not the sprocket. You don't think
a 28-tooth chainring would wear more quickly than a 40-tooth chainring?
28 teeth is getting into granny-gear territory. It was my understanding
that granny gears are typically made of steel and not aluminum precisely
because they're more prone to wear. Here's an old posting from Jobst that
I believe bears that out:

http://groups.google.com/group/rec.bicycles.tech/msg/28146c8f64ca1dc3

Ryan Cousineau said:

In article
<[email hidden]>,

landotter said:

Jeff Welch said:

I have an old huffy 3-speed, my best guess is that it is from the
1970's. I'm just learning how to maintain and repair my own bike, and
was wondering if it is possible to convert the current Shimano 3-speed
hub to one of their new Nexus 7-speed hubs. Where would I start to
figure out if it's even possible? (Tire size, frame fork, something
else?)

Sure, it's possible. A Sturmey Archer hub might be a better choice for
that frame spacing, if you don't want to spread it. Plenty of options
with and without brakes.

To elaborate, you'll almost certainly want to build a new wheel around
the Nexus hub, so just find out what the old wheel size was (you can
easily determine that from the tire markings or by taking it to a
half-competent LBS), and spec the necessary rim from there.

The Nexus 7 hubs can be built with rim, roller, or coaster brake setups,
so you can preserve the present braking setup or change it as you prefer.

As Landotter suggests, an S-A 7-speed will fit in your frame without
changing the rear spacing, though potentially at the cost of a bit of
efficiency and niceness that the Nexus hubs have. I doubt you'll notice,
and if you might, you'll probably want one of the even spiffier 8-speed
Nexus/Alfine hubs, or the also-spiffy SRAM iMotion 9 hub.

For any of those not-Sturmey hubs, respacing is a mildly unusual
mechanical challenge that will require either an enthusiastic amateur or
a mostly-competent LBS.

If you're taking a DIY approach, you'll need a new rear wheel, spec the
brake properly, a new shifter, and the various small parts. Plus you'll
need to re-space the frame if you don't go for the S-A 7.

Dealing with a shop that has done such a conversion before will help you
avoid one of my minor mistakes: if you order, for example, an Alfine
hub, the standard Shimano part number (at least around here) gets you a
bare hub, but no shifter or cabling (they come together as a separate
part number), no cog (your old 3-speed cog will work fine,
surprisingly), and no cable attachment thingy, magic lockring thingy, or
anti-turn nuts (again, the distributors in my country pack those three
pieces into a different part number).

Logically ordering just the shifter and the hub will get you a set of
elegant-looking mechanical lumps and a bit of research and waiting to
find the complete finishing bits.

I'd like to thank Dan Burkhart of Boomer Cycle (Ontario) for helping out
with that part. In the US, Harris Cyclery is the canonical source
knowledge and hubs-in-stock, and their prices are a benchmark, if a
beatable one.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

I like that Sturmey Archer hubs come with all the hardware neccessary to fit it into a bike. Shifter, cable, indicator chain, nuts, no-turn washers,everything comes in the package.
SA no longer makes a 7 speed, but the 5 speed is an excellent choice for most urban applications. I used one all winter. Works great.
The Shimano Nexus and Alfine hubs are a superb unit, but as Ryan says, the buyer must be aware that all the do-dads needed to fit and control them need to be ordered extra.
Hope you get your kit soon Ryan. You'll probably have it three days before the Canada Post tracking system realizes it's left Mississauga.
Dan Burkhart
www.boomerbicycle.ca

In article <[email hidden]>,

_ said:

Gary Young said:

_ said:

On Tue, 15 Apr 2008 22:22:36 -0500, Gary Young wrote:

> On Wed, 16 Apr 2008 02:30:10 +0000, Ryan Cousineau wrote:
>
>> In article
>> <[email hidden]>,
>> landotter <[email hidden]> wrote:
>>
>>> On Apr 15, 6:01 pm, Jeff Welch <[email hidden]> wrote:
>>> > I have an old huffy 3-speed, my best guess is that it is from the
>>> > 1970's. I'm just learning how to maintain and repair my own bike,
>>> > and was wondering if it is possible to convert the current Shimano
>>> > 3-speed hub to one of their new Nexus 7-speed hubs. Where would I
>>> > start to figure out if it's even possible? (Tire size, frame fork,
>>> > something else?)
>>>
>>> Sure, it's possible. A Sturmey Archer hub might be a better choice
>>> for that frame spacing, if you don't want to spread it. Plenty of
>>> options with and without brakes.
>>
>> To elaborate, you'll almost certainly want to build a new wheel around
>> the Nexus hub, so just find out what the old wheel size was (you can
>> easily determine that from the tire markings or by taking it to a
>> half-competent LBS), and spec the necessary rim from there.
>>
>> The Nexus 7 hubs can be built with rim, roller, or coaster brake
>> setups, so you can preserve the present braking setup or change it as
>> you prefer.
>>
>> As Landotter suggests, an S-A 7-speed will fit in your frame without
>> changing the rear spacing, though potentially at the cost of a bit of
>> efficiency and niceness that the Nexus hubs have.
>
> Does Sturmey make a 7-speed hub? If you mean the 8-speed hub, that may
> not be a good choice for the OP because the gearing is better suited to
> small-wheeled bikes:
>
>
Nonsense.

The only difference between a small-wheeled version and a large-wheeled
version of a successful Nexus conversion are the sizes of the chainring
and rear cog; the internal arrangements of the gearhub have no increased
suitablilty for wheels of any size. The only considerations of this
order that would be of importance are range of gearing available and
maximum torque allowed.

Take a look at Sheldon Brown's internal gear calculator:

http://sheldonbrown.com/gears/internal.html

If the OP has 26-inch wheels, a 170mm crank, and a 40-tooth chainring,
then adding the Sturmey-Archer 8-speed hub with its stock 25-tooth
sprocket would give him a range of 41.6 to 126.9 gear inches. That
strikes me as pretty high for a typical gearhub bike.

Now try the Shimano Nexus 8-speed hub with its stock 19-tooth sprocket
(all else held equal) and you get a range of 28.8 to 88.4 gear inches.

It's true that you could get the Sturmey-Archer down into the Nexus
territory with a 28-tooth chainring, but it's my understanding that such
a small ring would probably result in rapid wear of the ring and chain
(though perhaps I'm mistaken about that). Moreover, the OP, who has an
old 3-speed, probably doesn't have a crank with replaceable rings and
thus would have to buy a new crank and maybe a new bottom bracket.

This problem would be exacerbated if the OP's wheels are larger than 26
inches.

So, I don't think it's nonsense to say that the Sturmey-Archer hub is
better suited to small-wheeled bicycles (and actually I was just echoing
Sheldon Brown's judgment on that).

But it is not the HUB that is unsuited to small wheels, it's the rest of
the kit.

(And chain wear is not made worse by small sprockets until you get into the
11-12-13 tooth range; though 11's have been used on SA multi-gear hubs, and
I run a 13 on the Nexus.)

The OP would like to run a 8ish-speed gearhub on a large-wheeled
(26"-29"😉 bike. If they choose a Sturmey-Archer hub, they will have to
use a strangely large cog or a strangely small ring to get the usual
sort of gearing.

On a small-wheeled bike, that same hub gives gearing in a pretty typical
range using cogs and rings in quite mainstream sizes.

Indeed, the gearing issue for small-wheel bikes is such that Shimano
actually built a special hub and cassette with the ability to run a
9-tooth small cog:

http://www.sheldonbrown.com/capreo/index.html

So in short, the Sturmey-Archer 8 hub is well-suited to small-wheel
bikes because it allows use of readily available gearing sizes. On bikes
with larger wheels, normal sorts of gearing options require weird gears.

I do have a 64-tooth ring in my Pile, but it's hardly the sort of thing
I expect the local shop to stock.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."