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TdF and recumbents



 
 
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Old July 27th 08, 06:38 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Tom Sherman[_2_]
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Default TdF and recumbents

Hank Wirtz wrote:
On Jul 27, 8:52 am, Tim McNamara wrote:
Pat writes:
How would a recumbent handle the Tour?

You mean, if the UCI rules permitted the use of recumbents?

They'd like have some advantage on flat breakaways and time trials,
but the disadvantages in sprinting and climbing would scupper them
compared to regular bikes.

Another factor is that recumbents are heavier than regular bikes,
although there are now some 20-22 lb recumbents (e.gg., Bacchetta)
that can be bought by Joe Everedge. That would go a long way towards
improving climbing. My friend Don's titanium Bacchetta seems to work
pretty good on climbs.


I'm wondering how well they'd handle switchbacks, since all lowracers
are LWB, right? Plus, having the rider closer to the ground reduces
lean clearance.

Every commercially produced lowracer and most homebuilt ones are short
wheelbase [1]. I can only think of a few homebuilt lowracers that are
long wheelbase. What limits the turning radius on many lowracers is
running the chain by the front wheel for less drive train friction. This
limits the turning diameter to about 20 to 30 feet, or similar to most
front wheel drive subcompact cars on the market. So no problems on any
road built for automobiles.

Ground clearance is not an issue. On my lowracers the BB is about 46 cm
above the ground, and the bike can be leaned over by hand to more than
60° from the vertical before any "ground strike". As Jobst Brandt has
pointed out, if your lean angle goes much beyond 45°, you are crashing.
It is uprights that typically have the clearance issues (pedal strike)
with their lower bottom brackets and preferences for longer cranks than
are optimum on recumbents.

I think they'd be great for TTs and probably flat road stages. In the
mountains, both climbing and descending (unless the descent is a
straightaway), not so much.

With some vertical compliance built into the frame while retaining
torsional stiffness [2], passive suspension occurs which can help
greatly when traversing high speed bumps. The limited sight line over
obstructions is much less of an issue on a closed road that can be
pre-ridden (as is the case in the TdF). As for cornering grip/speed, I
see no theoretical or practical reasons which this should differ
significantly from that of an upright bicycle.

I will not repeat my discussion on climbing performance here that is
posted elsewhere in this thread.

And every time Tom uses the phrase "foam hat" I want to punch him in
the neck. Not that I'm pro- or anti-helmet, it's just a jackass thing
to call it.


Not in the face?

butbutbut, the primary component is expanded polystyrene which is
commonly known as Styrofoam®, and it is worn in the same location as
clothing items known as hats.

Is it also not being a jackass to spew pro-bicycle alleged protective
headgear propaganda that is not backed by evidence?

[1] This is defined by the BB being ahead of the head tube (SWB),
adjacent to the head tube (MWB) or behind the head tube (LWB). Actual
wheel base length does not factor, except to distinguish compact long
wheel base (CLWB) which is less than 1.5-m from LWB (1.5-m or greater).
[2] Quite possible on a single tube CFRP frame, and possible to a lesser
extent on metal single tube frames and only partially triangulated metal
frames.

--
Tom Sherman - Holstein-Friesland Bovinia
“Mary had a little lamb / And when she saw it sicken /
She shipped it off to Packingtown / And now it’s labeled chicken.”
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