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] http://www.sfu.ca/~rcousine/wiredcola/
President, Fabrizio Mazzoleni Fan Club
