On 12/29/2015 11:52 PM, William deRosset wrote:
Dear Will,
Expanding on my own post--is this a sign of senility?
No more so than a composer taking a delightful short melody and
expanding it into a full-fledged symphony. This is a wonderful
exposition, and I am sure you are 100% correct. It explains everything.
I did want to point out that the rear fender lines of early Rivendell
designs aren't accidental. They are consistent with most
non-constructeur builds of any era. There were a few Japanese bikes, a
few now very influential French bikes, and a few British bikes that
bucked this trend, but they were the exception, not ordinarily widely
produced, and, significantly, ordinarily featured vertical dropouts.
If you design around maximum "versatility", you build around
horizontal dropouts (fixed wheel/singlespeed/internal hub
gear/derailleur gears all work fine), and, if you maximize the tire
clearance for a given bridge-mounted brake, then you end up with an
offset chainstay bridge given the dropout configuration--bad fender
line, but big tire clearance without deflating the rear tire. This is
the bargain the early Rivendell designs made. You can do anything with
them, they're lovingly built of the best materials, fantastically
finished, and they maximized the stock technology of the mid-1990's.
Digression: I bet there is a lag from the widespread switch to
vertical dropouts and capitializing on the improvement to fender
alignment made possible by vertical dropouts. It sounds like Grant's
designs caught up sometime after the early bikes (including my own
Heron) and the early Atlantis were designed.
This switch to vertical dropouts resulted from a push from the MTB
world to shorten chainstays, one initiated by....Grant Petersen's MB
designs. It was enthusiastically picked up by the
22mm-max-tire-crit-racing bike designers that finally drove "road
bikes" into a ditch that Grant worked hard to avoid with his
road-going designs, before leading/following his demographic into
lovely cruisers and non-suspension light mountain bikes. "Gravel
bikes" and most cyclocross bikes, honestly, are probably the
non-racer's commercially-available road-bike answer to the mass-market
road-racing bike, which started to fall into the specialization trap
starting sometime before I rode road bikes thirty-five years ago, and
has stayed there, immobilized by strictures of "lighter, stiffer, and
more aero", and the "purposeful" racing aesthetic of really tight tire
clearances. Modern racing bikes are a ball to drive, but they're not
practical machines for most of us. Moving on....
In fact, many builders though the mid 2000's, including Waterford,
just specified a standard cast bit for the chainstay bridge, which,
depending on the chainstay length and the chainstay configuration,
would be located in different places relative to the rear axle, but
well away from the arc of an inflated tire as it was removed from a
(hypothetical) horizontal dropout. Basically, that one, even if a
threaded boss was added for a fender, had a go/no go spec, and users
of fenders could work out how to make up the difference on their own
time, and if the buyer isn't insisting on more closely-specified
design, or didn't know to ask, then why torture your builder to locate
that bridge in a given spot--about an "unimportant" detail? "It has
clearance, clarence...."
With vertical dropouts and braze-on brakes, there really isn't any
good functional reason (there are production reasons, but they're
minor if you care) not to place the bridges equidistant from the wheel
axis, and there really isn't any good reason not to include a threaded
boss perpendicular to the fender--unless it isn't a design
consideration or unless you specifically don't want fenders on the
bike. Even so, basic good design puts the support structure in the
right places. For example, my own Road Sport, built by Waterford
under contract to Boulder Bicycles, includes equidistant bridges and
would fit fenders and its design tire fine, even though the bike was
intended /not/ to accept fenders by its maker (no eyelets, no bridge
bosses. Mine ended up with one bridge boss, due to a prototyping
error...) due to the potential horror of toe clip overlap potential on
racing bikes.
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