Alistair, the Oz gear as you describe must be in fact a "Super Champion
Osgear'. If your Clements frame has a small bracket under the bottom bracket
you will need a short arm Osgear chain tensioner which fits to this bracket.
If no bracket is present ,you need the clip-on type arm. The clip holds it
to the bottom of the downtube. There may be a small flat plate with a hole
in it under the right hand chain stay, about 4inches in front of the dropout
centre. This mounts the shifting fork. If no plate is present , no worries,
as the fork comes with a wrap around clip to grip the stay. It all depends
whether your Dad's bike was built specifically for an Osgear. By the early
fifties they were considered obsolete and most riders ditched them in favour
of a Simplex , Huret or Cyclo. The super rich went for Campagnolo. So out
came the hacksaw and file and bye-bye Osgear brackets.
The control levers varied. 3 and 4 speeds were available and I know one
rider who modified his to 5 speed and then had a rod front changer to run
10speeds. Most levers had a chain tensioner device fitted too. This ran over
the bottom bracket to a pivotting bracket on top of the tension arm. The
final piece of the jigsaw is the chain guide and clamp which fits where a
front der ususally fits.This is nearly always missing and is difficult to
replicate as it has a left hand thread.
Gordon Selby of the VCC has written an excellent study booklet on the
Osgear. You would need to be amember to obtain one however. Osgears can be
noisy in use with overshifting essential. I have a 1949 A.S.Gillott and a
circa 1947 Paris so equipped. They were the gear of choice in 1938 when
derailleurs were allowed in the Tour De France. The Cyclo Ace employs a twin
wire system whereas the Osgear relies on a spring on the change fork.
Try nick at LLoyds cycles for transfers.
LLoyds
PO Box 133
Penrith
Cumbria
CA 10 3YA
UK
01931 714439
Mark Stevens, Dingwall Scotland. Oily bits ..........