Osgear
Here is an image
of the drive train of a 1951 Gillott. It started a 4-speed
Osgear which was converted to 6-speed (has anyone
else managed to do it?)
plus a Benelux rod changer on the front. This
is the Osgear with a tension adjuster on the sprung arm and a second
lever to reduce the chain tension for that extra bit of speed. It has
Mil Remo steel cottered cranks with possibly Mil Remo rings. The owner
says
he drilled two extra holes in the gear lever to accommodate the extra
gears.
Aub Denham writes:
I was interested in the article on Osgear. The photo (left) shows an Osgear with a 5-sprocket block and double chainwheel. A fixed arm was constructed so that the tension arm pivoted from beneath the bottom bracket. The frame is a Barnard, the bars Bartali. There were 3 of us in the Streatham C.R.C. who had Osgears at that time (circa 1952). One of the others I recall was Ron Hawes.
This Barnard didn't have a brazed on bracket although I'm sure that as it was built to my own spec. I could have had one brazed on (incidently the frame cost £12 10s). The position was altered by making a little arm (I think it was about 3" long) which was attached to the bolt on clip.
I also drilled a couple of extra holes in the gear lever quadrant from
5 to 7. This enabled the rider to move the lever that extra bit 'over
and back' to the desired position for an easier gearchange, with
practice, all in one motion. All in all a very
simple mechanism, which also benefitted from the fact that it
didn't get damaged if the bike went over, unlike some of the
Simplex/Huret types.
I got quite attached to the Osgear, although from memory it wasn't too good trying to change to a larger sprocket , under stress, going uphill, even with 'hooked' teeth on the sprockets. I think it was going out of fashion in the early fifties with the advent of the Simplex/Huret/Campag types, which gave a much smoother gear change. The Osgear did sometimes create a bit of noise which some riders in the bunch found 'disconcerting', although this meant they gave you a wider berth on occasions, so you see it had 'extra advantages'.
Oh, just remembered. I had 'vertical' rear wheel dropouts fitted also, unusual on a road bike at that time.
Right: Bernard on his 1950 Vecchietti with Osgear, Gnutti chainset and Simplex double changer on the front.
Below: Bernard with Osgear in the front row of the Herts Grand Prix (Junior) this time riding a CNC frame
Aub Denham writes:
I was interested in the article on Osgear. The photo (left) shows an Osgear with a 5-sprocket block and double chainwheel. A fixed arm was constructed so that the tension arm pivoted from beneath the bottom bracket. The frame is a Barnard, the bars Bartali. There were 3 of us in the Streatham C.R.C. who had Osgears at that time (circa 1952). One of the others I recall was Ron Hawes.
This Barnard didn't have a brazed on bracket although I'm sure that as it was built to my own spec. I could have had one brazed on (incidently the frame cost £12 10s). The position was altered by making a little arm (I think it was about 3" long) which was attached to the bolt on clip.
The photo was taken by Ted Lees, the event was the Streatham.C.R.C.'s club
25 in 1952.
Bernard Howard relates:
I rode an Osgear 1950-54 with the BLRC. Modifications were as
already commented upon, i.e. an extension bracket approx 3 ins long welded
vertically below bottom bracket. (I thought the original `clamp on` bracket was
useless). Although this meant the tension arm was moved backwards and lowered
it gave a wider choice of sprocket sizes. Chain length had to be adjusted so
that the arm 'chain guiding wheel', although much lower than normal , didn't
touch the ground when on the smaller sprockets/chain ring. (Mind you there was
only about an inch clearance in this situation)Bernard Howard relates:
I also drilled a couple of extra holes in the gear lever quadrant from
5 to 7. This enabled the rider to move the lever that extra bit 'over
and back' to the desired position for an easier gearchange, with
practice, all in one motion. All in all a very
simple mechanism, which also benefitted from the fact that it
didn't get damaged if the bike went over, unlike some of the
Simplex/Huret types.I got quite attached to the Osgear, although from memory it wasn't too good trying to change to a larger sprocket , under stress, going uphill, even with 'hooked' teeth on the sprockets. I think it was going out of fashion in the early fifties with the advent of the Simplex/Huret/Campag types, which gave a much smoother gear change. The Osgear did sometimes create a bit of noise which some riders in the bunch found 'disconcerting', although this meant they gave you a wider berth on occasions, so you see it had 'extra advantages'.
Oh, just remembered. I had 'vertical' rear wheel dropouts fitted also, unusual on a road bike at that time.
Right: Bernard on his 1950 Vecchietti with Osgear, Gnutti chainset and Simplex double changer on the front.
Below: Bernard with Osgear in the front row of the Herts Grand Prix (Junior) this time riding a CNC frame