Better handling?

Freewheeling wrote:

No, I don't buy it. I'm not talking about riding a conventional
centered position, but reweighting the way pros do on technical
descents, which is simply impossible on a recumbent. Can't be
done. Very few sportif riders do this of course, so your comments
may have some validity in that sort of situation... but under
typical road racing conditions against pros? No way.

Models with upright seating positions (e.g. Easy Racers) allow one a
fair degree of freedom to shift weight. I often lean forward when
descending to put more weight over the front wheel or backward when
ascending to maintain rear wheel traction. Doing this is necessary
when one is riding on dirt roads or trails where traction is
uncertain.

Pros are pros for a variety of reasons, but outstanding technical
descending skills is not high on the list. Road races are seldom won
on a technical descent.

I was involved in that discussion. Take a piece of standard plywood with
the long edge on the ground, and with some pegs close to the floor to stand
on while you straddle it, and something iike handlebars attached to the top
to hold onto. It's not difficult at all to imagine balancing such a divice,
although you'd have to get the hang of it. Now try attaching a recliner to
the top edge and see what happens to that balancing capability. Of course
this is in a static situation... but it's the essential reason that DFs are
"more maneuverable."

I agree that DF's are easier to balance and to maneuver at low speed.

At higher speeds, the time required to right oneself from a fall (an
initiation of a steering input) becomes shorter as forward speed
increases. At some forward speed this time becomes short enough that
the operator does not find it difficult to maintain stability. On
most DF bikes, this speed is close to zero. On most LWB recumbents
this is near walking speed. At typical descending speeds this kind
of instability is irrelevant.

I stand by my earlier statement in this thread that technical
descending speed is dependent mostly on the operator's knowledge of
the road, skill on the chosen bike, and risk tolerance.

--
Bill Bushnell
http://pobox.com/~bushnell/

"Bill Bushnell" wrote in message
...
Freewheeling wrote:

No, I don't buy it. I'm not talking about riding a conventional
centered position, but reweighting the way pros do on technical
descents, which is simply impossible on a recumbent. Can't be
done. Very few sportif riders do this of course, so your comments
may have some validity in that sort of situation... but under
typical road racing conditions against pros? No way.

Models with upright seating positions (e.g. Easy Racers) allow one a
fair degree of freedom to shift weight. I often lean forward when
descending to put more weight over the front wheel or backward when
ascending to maintain rear wheel traction. Doing this is necessary
when one is riding on dirt roads or trails where traction is
uncertain.

Pros are pros for a variety of reasons, but outstanding technical
descending skills is not high on the list. Road races are seldom won
on a technical descent.

I was involved in that discussion. Take a piece of standard plywood with
the long edge on the ground, and with some pegs close to the floor to
stand
on while you straddle it, and something iike handlebars attached to the
top
to hold onto. It's not difficult at all to imagine balancing such a
divice,
although you'd have to get the hang of it. Now try attaching a recliner
to
the top edge and see what happens to that balancing capability. Of
course
this is in a static situation... but it's the essential reason that DFs
are
"more maneuverable."

I agree that DF's are easier to balance and to maneuver at low speed.

At higher speeds, the time required to right oneself from a fall (an
initiation of a steering input) becomes shorter as forward speed
increases. At some forward speed this time becomes short enough that
the operator does not find it difficult to maintain stability. On
most DF bikes, this speed is close to zero. On most LWB recumbents
this is near walking speed. At typical descending speeds this kind
of instability is irrelevant.

I stand by my earlier statement in this thread that technical
descending speed is dependent mostly on the operator's knowledge of
the road, skill on the chosen bike, and risk tolerance.

Bill:

And I stand by my observation that those elements of balance and control
relevant at low speeds are also relevant at higher speeds, though the
feedback characteristics may be more subtle. I also think there are a lot
of pro cyclists who would disagree with the implication that descending is
relatively unimportant, though its clearly outweighed by other factors such
as climbing ability. Of course technical differences between riders on
descents are minimized because everyone basically rides the same bike and
muscular power and endurance are both less critical.

I'd also say that the idea that a modest increase in speed is all that's
necessary to bring "handling" on rollers up to match that of a DF is just
amusing, if you've ever actually tried it. Indeed, one factor that plays
no role at all on DF bikes was nearly insurmountable on a recumbent. The
regenerative feedback of the pedaling motion that tends to amplify and
bounce both bike and rider off the rollers at certain frequencies (about 60
rpm for me on the V-Rex) takes quite awhile to overcome, since modulation of
a translated horizontal motion seems to be a great deal trickier than
modulation of and compensating for the feedback of a vertical motion. (The
horizontal motion translated into a vertical amplitude that was nearly
impossible to control.) I eventually overcame the problem by practicing to
acquire an exceptionally smooth pedalling stroke, and I also began using
slightly shorter cranks. At some point I simply "broke through" the 60 rpm
barrier, and above the critical frequency the feedback disappeared.

But this was just one of a number of rather unexpected emergent
difficulties, and basically I just concluded that we're probably designed to
move better, and more effectively, in an upright position. It's not that
one can't compensate, and ride a recumbent well, and fast. But all else
being equal maneuverability of a DF is just significantly greater than a
recumbent. And obviously the more reclined you are the more pronounced the
difference.

The primary advantage of recumbents is their lower aerodynamic drag. I'd
also say that they're more comfortable for longer rides, which is probably
true for the average rider. But this latter advantage seems to disappear at
distances much greater than 100 miles. According to some members of this
list who ride randonneur events on both recumbents and uprights, the
recumbent is just as demanding, if not more so. (I can't verify this
myself, so have to rely on their testimony. I'm insufficiently insane to
ride in randonneur events.)


--
Bill Bushnell
http://pobox.com/~bushnell/

Freewheeling wrote:

I'd also say that the idea that a modest increase in speed is all that's
necessary to bring "handling" on rollers up to match that of a DF is just
amusing, if you've ever actually tried it. Indeed, one factor that plays
no role at all on DF bikes was nearly insurmountable on a recumbent. The
regenerative feedback of the pedaling motion that tends to amplify and
bounce both bike and rider off the rollers at certain frequencies (about 60
rpm for me on the V-Rex) takes quite awhile to overcome, since modulation of
a translated horizontal motion seems to be a great deal trickier than
modulation of and compensating for the feedback of a vertical motion. (The
horizontal motion translated into a vertical amplitude that was nearly
impossible to control.) I eventually overcame the problem by practicing to
acquire an exceptionally smooth pedalling stroke, and I also began using
slightly shorter cranks. At some point I simply "broke through" the 60 rpm
barrier, and above the critical frequency the feedback disappeared.

I was discussing descending on roads where centrifugal force from a
change of direction counters the bike's tendency to topple when
leaning. The longer wheelbase of a LWB recumbent causes a longer
delay between the initiation of a lean and its correction. The lower
center of gravity causes the lean to occur more quickly. Both of
these factors make a low, LWB recumbent less stable at low speeds.
For an upright bike the stall speed is close to zero. For a Gold
Rush or similar, it is closer to 2 or 3 mph, depending on the skill
of the operator. As speed increases the effect of this low-speed
instability gradually disappears, which is why I believe descending
skills have less to do with the bike (assuming the bike is high-speed
stable) and more to do with the operator's state of mind.

I believe that riding rollers is a low-speed stability issue,
complicated perhaps by the factors you mention above. There is no
change of direction when one initiates a "turn" on rollers, so the
centrifugal force is absent. Once the bike starts to topple there is
no countering force to right it. Those whom I have observed
attempting to ride a recumbent on rollers have found doing so
difficult at best.

--
Bill Bushnell
http://pobox.com/~bushnell/

Bill Bushnell wrote:
Freewheeling wrote:


I think you're both not acknowledging that an upright rider can use his
legs to lean the bike, which applies some steering input. This is far
less possible on a recumbent, since the legs are parallel to the roll
axis.

Have either of you tried to ride an upright on rollers equipped with
one of the hornless "Easy Seat"-type seats? Or ridden one so equipped
no-hands? Try it- you'll find out how much of upright's steering and
balance can be input through the legs.

Jeff

"Bill Bushnell" wrote in message
...
Freewheeling wrote:

I'd also say that the idea that a modest increase in speed is all that's
necessary to bring "handling" on rollers up to match that of a DF is just
amusing, if you've ever actually tried it. Indeed, one factor that
plays
no role at all on DF bikes was nearly insurmountable on a recumbent. The
regenerative feedback of the pedaling motion that tends to amplify and
bounce both bike and rider off the rollers at certain frequencies (about
60
rpm for me on the V-Rex) takes quite awhile to overcome, since modulation
of
a translated horizontal motion seems to be a great deal trickier than
modulation of and compensating for the feedback of a vertical motion.
(The
horizontal motion translated into a vertical amplitude that was nearly
impossible to control.) I eventually overcame the problem by practicing
to
acquire an exceptionally smooth pedalling stroke, and I also began using
slightly shorter cranks. At some point I simply "broke through" the 60
rpm
barrier, and above the critical frequency the feedback disappeared.

I was discussing descending on roads where centrifugal force from a
change of direction counters the bike's tendency to topple when
leaning. The longer wheelbase of a LWB recumbent causes a longer
delay between the initiation of a lean and its correction. The lower
center of gravity causes the lean to occur more quickly. Both of
these factors make a low, LWB recumbent less stable at low speeds.

But if I understand the situation correctly, we're are talking here about
high speeds, rather than low speeds. The issue is therefore more about
"holding the road" than about low speed stability.

For an upright bike the stall speed is close to zero. For a Gold
Rush or similar, it is closer to 2 or 3 mph, depending on the skill
of the operator. As speed increases the effect of this low-speed
instability gradually disappears, which is why I believe descending
skills have less to do with the bike (assuming the bike is high-speed
stable) and more to do with the operator's state of mind.

Again, if the issue is "holding the road" then the objective would be to
counter the centrifugal force without "leaning." Or, in other words, being
able to "counte-lean." I think Brandt's point (and mine, if I follow him
correctly) is that this is simply impossible on a recumbent.


I believe that riding rollers is a low-speed stability issue,
complicated perhaps by the factors you mention above. There is no
change of direction when one initiates a "turn" on rollers, so the
centrifugal force is absent.

One question: Have you ever ridden rollers? Very complicated situation.
It's not that tough to get up to speed either on a recumbent or an upright
(once you break through the feedback/amplitude problem).

Once the bike starts to topple there is
no countering force to right it. Those whom I have observed
attempting to ride a recumbent on rollers have found doing so
difficult at best.

You have to be much more vigilant, and correct much more quickly, that's for
sure. But that's at both low and high speeds.


--
Bill Bushnell
http://pobox.com/~bushnell/

wrote in message
oups.com...

Bill Bushnell wrote:
Freewheeling wrote:


I think you're both not acknowledging that an upright rider can use his
legs to lean the bike, which applies some steering input. This is far
less possible on a recumbent, since the legs are parallel to the roll
axis.

Well, that's essentially what I mean by a "counter-lean." But it's not just
steering, it's a matter of being able to steer without excessive lean so
that the bike holds the road better in a technical turn at high speed.


Have either of you tried to ride an upright on rollers equipped with
one of the hornless "Easy Seat"-type seats? Or ridden one so equipped
no-hands? Try it- you'll find out how much of upright's steering and
balance can be input through the legs.

Good point. By the way, one way to stabilize a recumbent if you start to
fall is to unclip and put your legs out to the side, and down. But be
careful not to touch the ground because leg suck is no fun at all.


Jeff

In article gI6Yd.34058$QQ3.5636@trnddc02,
"Freewheeling" wrote:

But if I understand the situation correctly, we're are talking here about
high speeds, rather than low speeds. The issue is therefore more about
"holding the road" than about low speed stability.


Again, if the issue is "holding the road" then the objective would be to
counter the centrifugal force without "leaning." Or, in other words, being
able to "counte-lean." I think Brandt's point (and mine, if I follow him
correctly) is that this is simply impossible on a recumbent.

Single track vehicles must lean when cornering otherwise they would
topple to the outside of the corner. Two-wheeled recumbents lean in
high speed corners just like upright bikes.

High speed cornering near the limit of traction is best done without any
sticking out of the knees or other "body english" (or pedaling, for that
matter). Brandt mentions this in his article under "Lean the Bicycle,
the Rider, or Both":

http://www.sheldonbrown.com/brandt/descending.html

I'm not sure what your overall point is. Holding the road is a function
of tire grip and road surface. Last time I checked, tires for
recumbents were made of the same stuff as road bike tires, differing in
some cases only by size, and roads are no different where recumbents are
ridden.

--
Bill Bushnell
http://www.pobox.com/~bushnell/