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

In article
,
landotter wrote:

On Apr 15, 6:01 pm, Jeff Welch 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:

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

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.