Thursday, September 29, 2011

An ode to the Raleigh Superbe and its Dynohub

On my walk to work today (I didn't ride as rain was expected and I had the child seat on my Orange
bike) I encountered no fewer than five  Raleigh Superbes.  A Superbe is a fairly common sight on the streets of Toronto, both the gentlemen's version as well as the lady's step through frame. I usually happen across one or two a week, but five in one day is exceptional.

Superbe from an eBay auction

Another beautiful example from this blog.

Another Superbe from mytenspeeds.
The Superbe came in a variety of colours since its inception, but it is the 'Bronze Green' model of the sixties and seventies that is by far the most common Superbe you see here in Canada.  One day, I hope to own one!  The Superbe undeniably has classic retro appeal, but what fascinates me most about this bike is its Dynohub lighting system.

Dynohub advert from SA heritage site.

The Sturmey Archer GH-6 Dynohub was the centerpiece of this system and it preceded the recent glut of contemporary hub dynamos by more than 60 years. Introduced in 1945, it was in production until 1984 according to this Sturmey Archer heritage site.   It is often mistakingly rated the same as contemporary hub dynamos ( 3W @ 6V) but it actually puts out around 1.8W @ 6V.  I've confirmed that my GH-6 saturates at about 330-330 mA, which is consistent with the later power rating.
The Sturmey Archer GH-6 Dynohub. My favorite hub in the whole world.
Photo from Sheldon Brown's Dynohub article.
In the world of LEDs this is still a very respectable amount of current, so the GH-6, despite its antique status, is quite capable of powering a modern lighting system (Update: after more testing I've determined that the Dynohub saturates at speeds above 35 km/h, so is, in fact, not very useful for powering LEDs without a magnet upgrade). They are reasonably easy to disassemble and service, provided the bearing races aren't shot and the armature coils are intact.  I pulled one apart that was in very rough shape but, despite a lot of internal corrosion, it seems like the armature windings are intact (at least by testing continuity with a multimeter, although I guess this could also mean they are prematurely shorted!).

Product photo from Sturmey Archer. Oddly, the front hub has been placed in a rear drop out.
I find the GH-6's lopsidedness appealing, although some might call it an odd looking duck with its one gigantic spoke flange on the dynamo side and a regular sized flange on the other.  I discovered that this unusual configuration can make getting a wheel built around the GH-6 take a little longer as the build calls for odd spoke lengths that most bike shops need to special order; I had the GH-6 from a Superbe rebuilt into a modern aluminum rim.  Before the build I stripped the hub apart, cleaned it and repacked the bearings. Despite its 42 years (at the time of servicing), it cleaned up beautifully and there was hardly any wear on the races.  I expect it will last a lifetime.

1 comment:

minisystem said...

Another great Dynohub resource with cool 'exploded' photograph of a disassembled GH-6.