Having ridden a freshly and carefully aligned frame (done by Ron Boi), I can say that precise alignment results in a lot of riding pleasure.
Ken Freeman Ann Arbor, MI USA
On Wed, Aug 26, 2009 at 3:12 PM, Doug Fattic <fatticbicycles@qtm.net> wrote:
> Getting the chain stays to be the exact same length (so a rear wheel is
> exactly in plane with the centerline of the front triangle) is one of the
> greatest if not the greatest challenge in building a custom frame. I
> encourage my framebuilding class students to choose horizontal dropouts for
> this very reason. In the old days before precisely machined frame
> fixturing, the adjustable screws could compensate for any discrepancies.
> Seat stay length is not quite as difficult because the chainstays are
> already brazed on providing some rigidity for checking the seat stay
> length.
> A difference of a millimeter in stay length is exaggerated by the physics
> of
> a wheel. In other words a mm of difference in a stay length will result in
> something like 3 mm of the wheel rim being out of plane.
>
> I know from experience of reconditioning classic frames that most of them
> will not center a rear wheel perfectly. Most likely they are off at either
> or both of the chain stays or seat stays. Stick a perfectly trued and
> dished wheel into your frame and find out for yourself.
>
> Doug Fattic,
> Niles, Michigan USA
>
> From: John Betmanis wrote:<johnb@oxford.net>
>
> A couple of reasons I can think of:
>
> 1. It's a carry-over from the way road bikes were always made, before
> derailleur gears were common. Tradition.
>
> 2. "Vertical" dropouts require very precise frame building with no means to
> alignin the wheel if the frame comes out a little "off".
>
> At 08:01 AM 26/08/2009 -0400, Stronglight49@aol.com wrote:
> >Stupid questions:
> >
> >1.) Noticed something in the photos of the Della Santa frameset
> >which brought to mind something which I never understood.
> >Is there a reason for using horizontal dropouts on a modern
> >road bike frame built for use of a rear derailleur?
> >
> >Call me lazy, but I really hate fidgeting with the rear wheels on
> >my old bikes - especially those (now most) which have mudguards
> >fitted.
> >
> >I have my own theories about the need for long dropouts -
> >something which was never required (or wanted) on classic
> >Touring bikes, even during the 1940s.
> >
> >So, next question:
> >
> >2.) What was the TRUE reason for use of long (or even shorter)
> >horizontal dropouts throughout the On Topic period?
> >
> >Feeling rather naive, but it seems that design of most ANY derailleurs
> >produced during the past 25 years or more have finally made horizontal
> >dropouts... as obsolete as buttons on trouser flys.
> >
> >BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA
>
>
> _______________________________________________
>
--
Ken Freeman
Ann Arbor, MI USA