Bicycle Mechanics - 20" wheel internal gear question

Looking for an affordable option to add gears to my daughter's ss bike with 20" wheels. Three speed is plenty. Any suggestions?

Affordable is the operative word.
In a nutshell ... NO.

There are many 20" wheel configurations, especially with the rising interest in recumbent type cycles.
But a 20" wheel with only 3 speeds, you'd likely have to lace one up.
And get all the hardware to make it function.

It'd probably be cheaper & easier to find a 2nd hand 20" wheeled kids mtn bike at a garage sale.
And that would probably be at least 6 speeds.

Just look for an old Schwinn (or post 1973 English) Sturmey Archer 3 speed with a working hub and shifter. Schwinns and later English bikes have 36 hole hubs and rims. It's almost imppossible to find 20" 40h rims.

I have several rebuilt SA hubs and usable shifters for sale, but in most areas you can still pick up a whole 3 speed bike for $35.

If you want to build it yourself--which isn't hard given the excellent instructions available from Sheldon Brown et al.--you could probably find a used Sturmey Archer 3sp hub, and pair it with any BMX rim, maybe even the rim currently on the bike. The short spokes are the biggest issue, but J. at Gaerlan (http://www.gaerlan.com/) can custom cut them for you at a reasonable price, if you don't have an LBS capable of doing it.

Good luck!

Jack

Probably not an economical plan.

Having a wheel rebuilt, buying hand cut and threaded spokes, not to mention figuring the shift cable routing. Sounds like a pretty expensive project to me.

Economical? Yes!

The last garage sale Schwinn 3 speed I bought cost me $10. No need for hand cut spokes to lace a 20" rim to an SA hub. You can even buy the right sizes double butted. Cables are cheap, zip tie 'em to the frame or find some old SA fulcrum clips. Anyone who pays someone else to build their wheels must have plenty of money to throw around.

No need for hand cut spokes to lace a 20" rim to an SA hub. You can even buy the right sizes double butted.

In quantities suitable for building just one wheel? Where??

I did this for an old folding bike that I have. I used a Shimano 333 hub instead of a Sturmey-Archer AW because the Shimano is 36-hole hub (probably the most common drilling #).

For the rim, I unlaced a 20" alloy rim from a girl's bike that had a coaster brake hub in it. I reused all of the spokes and nipples and laced in the Shimano 333 hub. I ran the cable all the way down from the shifter to the chainstay fulcrum clip. So, all of this ended up being relatively cheap in terms of cash but costly in terms of time and luck (finding all of these things).

The spoke length was around 7.25", and I have heard this is generally the right spoke length for lacing 36 hole Sturmey Archer hubs to 20" wheels.

I'd double check the following:
1. the dropout spacing on your bike is 110mm (if the dropout spacing is greater then you may need a longer axle on your hub or you will have to cold set the frame)
2. the dropout size (the slot for the axle) needs to be big enough for the axle.
3. make sure the anti-rotation washers fit in the dropout

P.S. I took the coaster brake hub and laced that into a 26" rim. If you're lucky the coaster brake hub will be the same size as your 3-speed hub allowing you to reuse the spokes and nipples.

Many thanks!

In quantities suitable for building just one wheel? Where??
http://www.gaerlan.com/bikeparts/parts/406wheel/wheelbmx.html Scroll down.

I should also think any BMX shop will stock appropriate lengths.

One of the bikes I've found out on large item trash day had a nice Shimano three speed hub & shift stuff. I gave it to my brother who put it on his son's 20" SS bike. Finished machine was a schweet little ride.

TCS

http://www.gaerlan.com/bikeparts/parts/406wheel/wheelbmx.html Scroll down.

Sure (I cited gaerlan as my source for spokes in my post above), but these are custom cut, and not double butted in the traditional 14-15-14 (or 2.0 mm - 1.8 mm - 2.0 mm) sense. No complaints though, as their prices are reasonable, turnaround quick, and the quality is first rate. I've built three wheels with spokes from Gaerlan and recommend them highly.

Jack

Any shop can get DT competition 14-15-14 (or 2.0 mm - 1.8 mm - 2.0 mm) spokes from QBP, in odd lengths from 183 to 195. Finding the shop that has them might be tricky. I suspect mail order BMX shops would be a good source.

Doesn't just about any shop have a Phil Wood spoke cutting jig? They can make any length you want. Mine charges 45 cents per spoke, total.

And, in a related coincidence, I just happened to have picked up a 20" wheel yesterday with a 3 speed hub on it. I have not looked at it closely, so I cannot even vouch for its integrity, but it seemed to work when I played with it. PM me if interested.

jim