I was pondering that also.
I wonder if it came about at the time as Hugh says the 5sp cluster an hubs
started to get more modern with FB-Campy-Airlite came into high mode.
Maybe the machining on hub shells,and standardising frame width for
practical build reasons.
I also think that about the same time, tieing and soldering was getting old
hat somehat and the wider hub certainly gave more stability on the banked
tracks.
One could do much more changing around for those years where 120 was the
standard.
Then when the road got wider it changed again, but track was settled in and
left as is except for some of the newer narrow gauge aero hubs were custom
made for "slippery" bikes.
Ted Ernst
Palos Verdes Estates
CA USA
>
> In a message dated 08/05/2007 01:18:44 GMT Standard Time,
> fred_rednor@yahoo.com writes:
>
> Actually, the switch to 120mm strikes me as somewhat of a
> puzzle.
>
>
> It may not be the reason for switching to 120mm, but it was really handy
> for
> those of us who way back then had only one pair of racing "sprint" wheels
> with fixed-free rear hub -- they worked on the road bike with 5-speed
> block and
> on the track bike too, without having to mess around with spacers.
>
> Hugh Thornton
> Cheshire, England