I think Steven's point is that the clearance between the tire and chainstays is usually much less than at the seatstays. Horizontal dropouts allow one to cock the wheel slightly, which for many wheel/frame combinations will allow the tire to just miss the chainstays. Flip the QR on the rear brake and you can often get home without further ado (or, if it's a Varsity, you just continue riding it that way until something alse happens). With vertical dropouts you can only cock the wheel vertically, which is not usually where the problem needs to be addressed.
Of course, a well-built wheel, in good shape and made with quality parts, should never break a spoke.
Steve Barner, Bolton, Vermont
> Date: Fri, 15 Aug 2003 22:06:25 -0700
> From: Chuck Schmidt <chuckschmidt@earthlink.net>
> To: classicrendezvous@bikelist.org
> Subject: Re: [CR]Re: Vertical dropouts
---Snip---
> The reality is that a broken spoke is no different with horizontal or
> vertical dropouts; either way the spokes need to be adjusted to
> compensate for a broken spoke.
>
> Chuck "I'd rather ride home than walk" Schmidt
> South Pasadena, CA