Several years ago I thought that I was getting quite a deal when I purchased this old Motobecane Mirage for twenty bucks. Take a look at the Bike from Hades, when ride quality is the issue.

The bike would hop at just about any rpm. I took it out for one ride and hung it up in The Old Shed.

Anyway, thought you might get a kick out of it:-)

Motobecane_Durham_Crank_6..jpg Motobecane_Durham_Crank_3..jpg

Motobecane_Durham_Crank_5..jpg Motobecane_Durham_Crank_4..jpg

Somebody liked 'em. Those teeth appear to have some good wear. Any more info about Durham around?

Edit: I see VeloBase has a pic of a 5pin [hollow] model. You should add the [solid] 3pin to the collection.

A Durham (Despite the English sounding brand name it's from California) elliptical chainring from the 70's! Looks super cool compared to the lumpy looking Biopace, but I guess more biomechanical research went into developing Shimano's version. I was surprised to find out ths year that elliptical chainrings made their comeback into new bikes when it was mentioned during the TDF broadcasts this summer.

Chombi

Whoa Wut!?

how the heck do you calculate gear inches on that thing?? "Well sometimes its 90.6, sometimes its 4.3"

Honestly, any shifting/gear skipping problems are just as likely to be caused by that POC plastic simplex derailleur.

Chombi - Biopace was a sound design that did what it was supposed to but was a marketing disaster for Shimano... the lumpy look is what set it apart from elliptical chain rings.

Have they come up with a compelling explanation as to why yet? I can feel the difference between my Bio-Pace and Regular chainrings, but I can't notice any improved/reduced efficiency or power

Trust me, I have ridden lots of vintage road bicycles with the Simplex transmission, and that is not the ride feel issue. When I say the bike hops, I mean it hops up and down. Sort of seems to bounce and that is at low rpms. I would hate to think what this monster would feel like at 70+. One's vision would be blurred, for sure.

oh wow that is a horse of a frighteningly different color! I figured you meant the chain hops

I believe oval chainrings were originally done by Oscar Egg.

Proves to show that bikes were so perfectly beautiful by the 80's that many people felt funny about putting something lumpy looking on them that could negatively affect their aesthetics........blame it on picky future C&Vers??

Chombi

If that's true, fine, but I'm LOLLing either way.

Bobby Julich loved his ovals on his Cervélo Soloist (Feb 2008):