View Single Post
  #1  
Old July 27th 08, 12:48 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Tom Sherman[_2_]
external usenet poster
 
Posts: 9,890
Default TdF and recumbents

Pat ? wrote:
How would a recumbent handle the Tour?


Anyone that claims to provide a definitive answer is blowing smoke up
your backside, since the information does not exist to provide the
answer. You will find a lot a negative answers based on misinformation
by "experts" who have no experience or knowledge, however.

As a starting point, consider that there are only a few hundred state of
the art performance recumbent bicycles in existence (compared to tens of
thousands (or more) of state of the art upright bicycles), and most
people have never seen one unless they attend a recumbent oriented
racing series (and even there, most of the recumbents will not fit that
definition). Furthermore, of this relative handful of recumbents that
are lightweight (less than 8 kgf) and put the rider in an aerodynamic
position, only a small fraction are ridden by riders who could keep up
in a CAT 2 race on an upright, to say nothing of UCI professional level
riders. So all observations made of recumbents in the real world can
pretty much be thrown out as irrelevant to the original question.

Unless someone can demonstrate that upright riders can develop
significantly more sustained power than recumbent riders [1], there can
be little doubt that a recumbent with a seat-back 20 to 30 from the
horizontal and the pedals 20 to 25 cm higher than the seat will be
faster on the flats than a drop bar road bike or an upright TT bike.
This advantage becomes more significant in windy conditions, due to
lower wind speed within the 1 meter boundary layer between the
atmosphere and the ground. For equally talented and trained riders, the
recumbent lowracer would be faster during a flat to rolling time trial
or on a breakaway on a flat stage.

An upright sprinter can develop significantly more short term power than
a recumbent rider, based on the available information. However, as
anyone who has watched a race knows, sprinting prowess is of little
advantage, unless the sprinters are in the leading peloton near the
finish of the stage. Due to the lower frontal area of a recumbent
lowracer and the inability for an upright to effectively draft the
recumbent, the upright sprinters would not be in a position to use their
advantage in short-term power.

And of course, there are the mountain stages, where conventional wisdom
says that recumbents can not climb. The first thing is to throw out all
personal observations here, since they invariably involve recumbents
that are heavier than a state of the art CFRP lowracer and riders
considerably less able than a UCI professional.

The key is to remember that aerodynamic resistance increases with the
square of the rider's airspeed. Therefore, for average club riders, both
upright and recumbent riders will be going slowly enough that rolling
resistance and mechanical losses in the drive train will dominate, which
favors the upright. However, with a professional level rider putting out
400W on a climb, speeds become high enough that aerodynamics does
matter, even on a relatively steep climb, and an upright rider out of
the saddle is not very aerodynamic. Is the aerodynamic advantage of the
recumbent at very high rider output levels enough to compensate for the
advantages of the upright? I do not know, and more importantly, neither
does anyone else.

[1] The few studies down indicate that this is NOT the case.

--
Tom Sherman - Holstein-Friesland Bovinia
"People who had no mercy will find none." - Anon.
Ads
 

Home - Home - Home - Home - Home