Way back when, it allowed for a faster rear wheel change in endurance racing. Rears get changed more often than fronts. I think Honda started the trend, with some of their works bikes. Nowdays it's a marketing thing.

Since we seem to be on a 916 hijack of this thread, here's another picture. It's a '98 916 SPS that I sold a few months back.

JR



http://forums.pelicanparts.com/uploa...1275431753.jpg

+1 It is stupid easy to change wheels, especially if you have an under-tail exhaust. I suspect there are other reasons too like weight.

Like 'dog mentioned, it was originated for rear tire changes during endurance races like the Suzuka 8-hour. I think Honda started it with their RC30s. Ducati emulated it on the 916.

For street bikes, it's mainly fashion. Ducati admits that there isn't any weight savings to having a SS swingarm compared to a DS swingarm. The added material needed for the SS design for stiffness ofsets the lack of having material for the "other" side. Note the 999 went back to a DS design.

I'm pretty sure it originated with the Honda RVF750 in 1985, which was a race bike built to the TT-F1 regulations, and a precursor to the RC30. It was raced that year with both a single- and a double-sided swingarm. There's no doubt that it is heavier than a conventional swingarm and I question how much faster it is with tire changes. I have a few works swingarms for other bikes, that have been designed to facilitate quick tire changes and they can change a rear tire as quickly as they can load 6-7 gallons of fuel.

JR

EDIT: I got to thinking about this and recalled that the single-sided arm originated a few years before Honda used it, on a series of endurance bikes built by ELF. They had a lot of unconventional design details...

My Honda VFR 750 had a sticker on the swing arm that said, "ELF design"...