Eyebrows123

Just wondering if I could get some advice here, currently got a sturmey archer AG dynohub that we're fitting to a tandem. However, the tandem is set up to use a hub brake at the rear (as well as a v brake). So, was wondering whether it's possible to convert the dynohub to a hub brake, can you just swap the dyno out and put the hub brake in? I.e. without changing the hub entirely, just that function part on the side of it?

Hope that makes sense in what I'm trying to do, if not, let me know and I'll try to explain it better! Any help would be very much appreciated!

frameteam2003

Yes you can. You can also go the other way but you need to drill the 4 small holes just right.

clubman 

But what about the other parts you'd need? Or if you're thinking TCW coaster brake, the internals would be quite different.

Eyebrows123

The dynohub is already attached using the 4 holes, I just want to take the dyno part out and replace it with a brake. Is that possible? Will any SA drum brake fit or are there vastly different sizes and how do I figure if they'll fit mine or not?

clubman 

I have a Sturmey service manual that shows different part numbers for the shell of the AB and AG hubs fwiw. Online you can find exploded diagrams for each hub here. https://www.sheldonbrown.com/sturmey..._3-spd.html#ag
frameteam2003 says you can do it...Tony Hadland would likely know for sure. I'd rather source an AB hub

fietsbob

I think you cannot, you have a wheel building project ahead of you.

Currently the S-A company relocated by bankruptcy sale to the Sun Race corp

has a Drum Dynohub for the Front Wheel and Drum IGH rear Wheel hubs..

they also have adopted Aluminum hub shells , which support the spoke bends better,
they add steel for the brake drum.

The S-A 'Elite' series was aluminum hub shells when they were still in UK.


[30 year old 'elite' drum brake hubs (F,w/o dynamo, rear taking a 6 speed Freewheel) on my winter bike ]

...

JaccoW

Jup, this will require a rebuild.

Take a look at the SA XL-FDD. A 90mm drum with modern dynohub internals.

There are plenty of cheap Sturmey Archer front wheels to be found around here and even plenty of affordable old-school tandems.

frameteam2003

Ag and ab are the same hub shells Ag shells have 4 holes drilled in them, AB shells do not. It's just that simple---any AB brakes will work. Now SA did make 90mm brakes so you will need the standard size 70mm brakes. don't make it complicated.

Eyebrows123

Our front hub is already a SA brakes hub, no idea what type, think 70mmm but not sure.

How do I measure the 70/90mm, is that the inside of the braking surface?

One easy and quick way to find out...I'll check if my front hub brake fits on the rear, providing it's the same size at least. Will try check when I get more time