In article <[email hidden]>,
Quoted message said:Hi,
I read that recumbents are the fastest bikes, and that the
speed record on flats was set by a recumbent at 81 mph.
This raises several questions:
1) If recumbents are so fast, why don't we see more races
with them? The Tour De France still uses road bikes...
UCI rules prohibit anything but a conventional road bike,
very strictly defined by the rules, including such details
as the allowable distance the seat may be ahead or behind
the bottom bracket. The good reason for doing this is that
they want the spirit of bike racing to be a contest of
human performance, not bike technology. They even say that
in their rules, with a clear assertion that this spirit
will drive UCI rulings and regulations. As it is, 'bents
are not faster everywhere, so you would likely see the
phenomenon of riders changing bikes from stage to stage
(which they already do) and even in some cases on different
parts of each stage (which one or two riders has tried).
The bad reason for doing this is the UCI is quite hidebound
in its nature, got badly freaked out when Mochet set a
putative hour record in 1938 with a recumbent bike, and
promptly banned recumbents from all bike races. A lot of
constraining decisions have been made since then, and the
result is that bikes today look close enough to old racing
bikes that a postwar rider would recognize them as
incremental adjustments to his classic bike, and a pre-war
rider would only be impressed by the addition of derailleur
gear-changing.
Quoted message said:2) If recumbents are so fast, why don't people ride them
more often? Certainly a bicycle that's fast enough to
keep up with traffic would eliminate the need for a
biking lane or worries about riding on the left, etc...
they could even be used on the freeway. People could
cover more distances faster -- they would become an
even better form of transport.
A recumbent is not quite as at ease in tight circumstances
as a road bike. It doesn't generally climb hills as well
as a road bike. It rarely accelerates as well. And the
fastest straight-line ones are incredibly constrained
designs that are barely comfortable enough to use for
record attempts. Normal recumbent designs cannot even be
ridden up a curb without considerable skill or daring. For
a typical rider who wants to climb hills or navigate city
streets, a hardcore faired recumbent is not an ideal
choice. As recumbents get further away from that essential
type (unfaired recumbents, trikes, semi-upright or non-low
designs, etc.) they lose recumbent advantages
progressively until you get to the extremes: there are
bent designs on the market that are both heavier and less
aerodynamic than a conventional bike. What they offer is
only the distinct seating position of a recumbent, which
is what many recumbent riders are seeking, for comfort or
physiological reasons.
To get an idea of how important pure straight-line
performance is, note that it can be improved notably on most
road bikes by using a time-trial setup, and that adding a
relatively simple nose fairing would help even more. Yet few
riders ride their TT bikes on the road unless it is their
only bike or they are TT training. Virtually none bother to
fair their conventional bikes.
Quoted message said:3) How are these time trials conducted? For example, was
the 81mph record achieved by somebody pedalling from a
dead standstill, or were "interesting" tactics allowed
that make the achievement less than it seems?
This is a "flying 200 m" record. The bike has a considerable
(and I think unregulated by the record rules) distance to
accelerate while approaching a 200m timing trap. Time
through the trap is converted to a speed reading. This is
the _de facto_ human-powered land speed record, currently
held by Sam Whittingham riding the Varna Diablo II, designed
by George Georgiev, at 81.00 mph.
The hour record, which gives you a good idea of sustained
maximum-effort speed in a faired low-racer 'bent by an elite
athlete, is 51.33 mph, set by a German team with their
"White Hawk". Slower riders may experience a lower top
speed. By a fair bit.
Recumbents are really cool, but they're also notably
compromised vehicles. For a long-distance tour over
relatively flat ground, a recumbent might be the fastest,
easiest choice of all. But deviations from that formula tend
to be at the peril of the recumbent's performance advantage.
--
Ryan Cousineau, [email hidden]
sfu.cawiredcolaOpen ↗ President, Fabrizio
Mazzoleni Fan Club
