Clearance problems with freewheel attached to 3spd hub

[fitek]

I bought one of the 3 speed Sturmey Archer wheels from UtahTrikes and made an adapter to fit a freewheel and a #219 sprocket onto the wheel. Basically, there are just 3 holes drilled in the stock sprocket and the adapter has 3 holes too. They get bolted together.

Trouble is, the height of this assembly is too much and there is not enough axle left to really secure the drive side once that weird metal arm is put over the end of the axle. I can only halfway thread a low profile nut on.

Ideas?

There is a dust cap on the hub which I can remove which will give me about 2 more mm to play with. Replacing the Sturmey Archer sprocket with something that isn't dished might work, but I didn't find anything like that at the LBS.

One other worrying thing, the whole assembly fits perfect into my downtube folding bike's rear end which used to have a SunRace derailleur. I guess I'll have to squeeze the rear end together too...

 

[MitchJi]

Hi,

Gary sells a similar adaptor here:
http://www.tppacks.com/products.asp?cat=26

-Speed Hub-Compatible Freewheel Adapter Kit
Allows a standard BMX 1.37" 24 TPI freewheel to be used in conjuntion with a larger, independent motor-driven sprocket on a Nexus, SRAM or Sturmey-Archer 3-speed hub. Having a "second" freewheel in back eliminates the need for installing a special freewheel-equipped crankset, so that the motor doesn't drive the pedals, when it is on. Four holes are provided in the adapter base that match up to a standard 16T 3-splined Nexus cog (not supplied...). The steel cog is then sandwiched between the freewheel adapter and the motor sprocket/adapter, using the supplied stainless steel button-head screws, nuts and lock washers, along with the supplied black-anodized aluminum spacers/standoffs. This assembly fits on the splined hub and is held in place with the standard circlip, provided with the hub. Then, a standard BMX-type freewheel, which are available with 16-22 teeth, is screwed onto the feeewheel adapter. This adapter is compatible with all popular 3-speed hubs, including Nexus, SRAM and Sturmey-Archer.

Kit includes the adapter, four stainless steel 1/4-20 x .75" buttonhead scews, with lock washers and low-profile stainless steel nuts, and the required washers/spacers. In addition, four linger 1/4-20 x 1" screws and four anodized aluminum standoff spacers are also provided, which allows for various chainline options for the motor-driven sprocket.

Price: $25.00

Described in this thread:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=12267

 

[fitek]

Well the critical piece with that adapter is that it will save me a few mm if the sprocket adapter is on the inner side of the 22t sprocket. Currently both the freewheel adapter and sprocket are on the outside. But, that's only about 1/3 of the depth of the nut though so in the end it wouldn't get me to where I want to be. I guess if the frame of the bike is made of steel rather than aluminum the dropout wouldn't be as thick and so more axle would be available. But that's what I've got so that's what I'm going to use.

I'm going to try this thing out without the freewheel adapter as it has just been a total pain in the butt overall.

 

[fitek]

Not using the freewheel adapter isn't really an option. I've given up on this approach.

I guess I'll have to try this idea out on another bike.

 

[TylerDurden]

FWIW, Harris sells a long axle for the AW. It might work with yours.
6.25"

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

 

[fitek]

Awesome Tyler, that looks like it will do it! Just placed my order with Harris Cyclery.

 

[TylerDurden]

You might also need the longer indexing rod:

http://www.bikepartsusa.com/bikepar...cher--gear-index.-163mm.&category=hub-3_speed

 

[MitchJi]

Hi,

I bought one of the 3 speed Sturmey Archer wheels from UtahTrikes and made an adapter to fit a freewheel and a #219 sprocket onto the wheel. Basically, there are just 3 holes drilled in the stock sprocket and the adapter has 3 holes too. They get bolted together.

Trouble is, the height of this assembly is too much and there is not enough axle left to really secure the drive side once that weird metal arm is put over the end of the axle. I can only halfway thread a low profile nut on.

Ideas?

Gary sells a similar adaptor here:
http://www.tppacks.com/products.asp?cat=26

Described in this thread:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=12267

…Normally, I would use a Shimano Nexus-3 hub, but I found a Sturmey-Archer SRF3 hub already laced into a nice 20" rim at UtahTrikes.com for a total of $49, so I decided to try one.…

Well the critical piece with that adapter is that it will save me a few mm if the sprocket adapter is on the inner side of the 22t sprocket. Currently both the freewheel adapter and sprocket are on the outside. But, that's only about 1/3 of the depth of the nut though so in the end it wouldn't get me to where I want to be.

Just out of curiosity why does Gary's adaptor work on the SA Hub on a 20" rim purchased from Utah trikes but it won't work on your identical rim (also from Utah trikes)?

 

[TylerDurden]

Gary used a cog with dishing to aid in clearance:

There's separate chains to the rear for the motor and for the pedals. Both rear sprockets are attached to the SRF-3 hub, via a standard Nexus 16T splined steel cog (also available at UtahTrikes.com...). I'm using a Nexus cog because they are dished slightly, which helps in the alignment of the chains. This steel cog is sandwiched between a 22T 4-hole 64mm BCD "granny gear" aluminum mountain bike sprocket, and a 94T aluminum #35 heavy duty go kart sprocket I got from gokartgalaxy.com.

Gary also milled off the lugs on his FW:

I found there is a slight difference between the Nexus and S-A 3-speed hubs in how far out the hub end extends, past the circlip. It is a bit wider on the SRF-3, which meant I ended up with a slight clearance problem on this bike. I ended up having to Dremel off the four "tabs" that stick out on the freewheel. These are normally used to remove the freewheel. If I ever end up needing to replace this $20 Shimano FW and I can't get this one off, I'll just use another adapter.

 

[fitek]

There are no tabs on my adapter.

The fit is really close, I assume the drop outs on Gary's steel frame bike are not as thick as the aluminum ones on my folder which are quite beefy.

This wheel would work in the aluminum folder if I didn't use the freewheel. It adds some thickness to the whole setup no matter which way I assemble this sucker and it's just a bit too much...

The replacement axle from Harris Cyclery is the same as the one I have, so no go there.

I think I'm going to just use this wheel on a steel frame bike.

 

[fitek]

I will assemble the wheel again and post a photo of what the thing looks like from the side.