Re: [CR]Mandaic Frame

(Example: Bike Shops)

Date: Sat, 4 Aug 2001 22:28:40 -0400
Subject: Re: [CR]Mandaic Frame
From: "Richard M Sachs" <>

columbus genius tubing... another from the long list of blister-packed tubesets created to help make monkeys out of consumers. rant over. e-RICHIE

On Sat, 4 Aug 2001 22:14:02 EDT writes:
> Columbus Genius was a top of the line Nivacrom alloy product in
> the early
> 90's (introduced in '91). Wall thickness is .7/.4/.7 for top and
> downtubes in
> "standard oversize," and either single butted .8/.6 or double butted
> .75/.4/.6 seattubes. There is also an outside butted seattube
> available, as
> well as a 33 mm O.D. downtube with .8/.5/.8 walls and a 31.7 mm O.D.
> seattube
> with single butted .8/.5 walls.
> The unusual thing about Genius is what Columbus calls
> Differential Shape
> Butting. The headtube end butts on the top and down tubes are longer
> on the
> top and bottom, respectively, and the BB end of the downtube and
> seattube
> (except the D.B. seattube) have butts that are longer in the
> horizontal plane
> than the vertical plane. The idea, as I understand it, is to remove
> materiel
> from the less highly stressed areas of the butted portion of the
> tube. There
> are little raised bumps inside the ends of the tubes so the builder
> can
> orient them correctly (I scrapped a Genius downtube by assuming that
> the
> notch on both the toptube and downtube were to be on the underside
> of the
> tube-wrong!)I've also heard from reliable sources that some well
> regarded
> builders (none of them Listmembers!) had downtube failures when
> using
> Genius-has anyone else heard this?
> Regards,
> Wes Gadd