Unfaired Recumbent vs. Upright Speed Comparisons

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

<snip>

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of 40
km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

<snip>

Quoted message said:

Yes, folks, according to this study, that same 75 watts of power that produces ~10 mph on your
hybrid upright bike would have you screaming along at 25 mph in a fully-faired lowracer. Wow.

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8 mph for 75 watts of input?
That is incredible; but it does begin to explain how Sam Whittingham was able to power a faired bike
to 81+ mph on level ground. (remember: wind drag increases as the *cube* of velocity).

-Barry

B. Sanders said:

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8 mph for 75 watts of input?
That is incredible; but it does begin to explain how Sam Whittingham was able to power a faired
bike to 81+ mph on level ground. (remember: wind drag increases as the *cube* of velocity).

I think you had it right the first time - the MPH figure was labeled as being obtained with 250 W of
input. The power figure is labeled as watts at 25 MPH.
--
Russ [email hidden] the wabbit to reply "No, see, it's not something
you 'experience' - it's something that you posess. You know, that fine 'recumbent butt' - a
distinguishing characterisitic of a recumbent cyclist." -Geoff Adams, on 'BROL

Thanks, Barry. Very interesting!

Scott

"B. Sanders" <[email hidden]> wrote in message news:<L_oob.52992$9E1.241427@attbi_s52>...

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

<snip>

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

<snip>

Quoted message said:

Yes, folks, according to this study, that same 75 watts of power that produces ~10 mph on your
hybrid upright bike would have you screaming along at 25 mph in a fully-faired lowracer. Wow.

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8 mph for 75 watts of input?
That is incredible; but it does begin to explain how Sam Whittingham was able to power a faired
bike to 81+ mph on level ground. (remember: wind drag increases as the *cube* of velocity).

-Barry

"B. Sanders" <[email hidden]> wrote in message news:<L_oob.52992$9E1.241427@attbi_s52>...

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

<snip>

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

<snip>

Quoted message said:

Yes, folks, according to this study, that same 75 watts of power that produces ~10 mph on your
hybrid upright bike would have you screaming along at 25 mph in a fully-faired lowracer. Wow.

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8 mph for 75 watts of input?
That is incredible; but it does begin to explain how Sam Whittingham was able to power a faired
bike to 81+ mph on level ground. (remember: wind drag increases as the *cube* of velocity).

-Barry

I think you are reading the chart wrong. it is 42.8 mph @ 250 watts and 25 mph @ 75 watts.

Craig

"Russ Price" <[email hidden]> wrote in message
news:bCtob.68816$Fm2.56622@attbi_s04...

Quoted message said:

B. Sanders said:

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft

material)

Quoted message said:

Quoted message said:

Quoted message said:

42.8 75 recumbent (very aerodynamic hard fairing)

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8

mph

Quoted message said:

Quoted message said:

for 75 watts of input? That is incredible; but it does begin to explain

how

Quoted message said:

Quoted message said:

Sam Whittingham was able to power a faired bike to 81+ mph on level

ground.

Quoted message said:

Quoted message said:

(remember: wind drag increases as the *cube* of velocity).

I think you had it right the first time - the MPH figure was labeled as being obtained with 250 W
of input. The power figure is labeled as watts at 25 MPH.

I'll chalk it up to the late hour. 42.8 mph did seem ridiculously high.

-=B=-

"cbb" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message

news:<L_oob.52992$9E1.241427@attbi_s52>...

Quoted message said:

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

<snip>

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed
of 40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft

material)

Quoted message said:

Quoted message said:

Quoted message said:

42.8 75 recumbent (very aerodynamic hard fairing)

<snip>

Quoted message said:

Yes, folks, according to this study, that same 75 watts of power that produces ~10 mph on your
hybrid upright bike would have you

screaming

Quoted message said:

Quoted message said:

Quoted message said:

along at 25 mph in a fully-faired lowracer. Wow.

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8

mph

Quoted message said:

Quoted message said:

for 75 watts of input? That is incredible; but it does begin to explain

how

Quoted message said:

Quoted message said:

Sam Whittingham was able to power a faired bike to 81+ mph on level

ground.

Quoted message said:

Quoted message said:

(remember: wind drag increases as the *cube* of velocity).

-Barry

I think you are reading the chart wrong. it is 42.8 mph @ 250 watts and 25 mph @ 75 watts.

Thanks Craig. Yeah, you're right; I did misread it. Still....adding a fairing can more than *double*
your speed for a given power input. That's big news.

-=B=-

[Strange, when I post from the Slurp.net newsreader, my posts never show up on the MSU Newsreader.
Slurp maybe hosts some spammers and MSU bounces all their posts??]

There's been talk about a world unfaired record but I guess no one can agree on what that means. The
Euro unfaired class allows tailboxes, for instance.

Maybe they should have brand-based stock classes, like sailing has design classes.

The winning time for the Eurostyle unfaired hour race this year was about 31mph.

These racers aren't totally elite, so that would seem to put them on par with the best UCI bikes. If
the best UCI racers adapted to these Eurostyle (tailboxed) lowracers maybe they could go, what, 35
miles in an hour?

I think that totally unfaired lowracers are still faster than UCI bikes. Andreas Weigel isn't a
bigtime racer at all, I gather, but he came in a close second to pro Sean Wallace in a 20km USCF
TT in San Diego. I lapped a USCF field with mine and I don't normally do that. : ) Tim Brummer won
his age division at the USCF TT 40k Nat'ls against very fast people and he's not a pro either I
don't think.

--

Jeff Potter
****
*Out Your Backdoor * outyourbackdoor.comoutyourbackdoor.comOpen ↗ publisher of outdoor/indoor do-it-yourself
culture... ...offering "small world" views on bikes, bows, books, movies... ...rare books on ski,
bike, boat culture, plus a Gulf Coast thriller about smalltown smuggling ... more radical novels
coming up! ...original downloadable music ... and articles galore! plus national "Off the Beaten
Path" travel forums! HOLY SMOKES!

When you kick their collective asses, you won't need any data!
B. Sanders <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

Here's an interesting web page which cites several experiments attempting

to

Quoted message said:

answer this question. It includes thoughtful narrative from several

riders

Quoted message said:

who offer sincere observations on the topic.

neci.nj.nec.comcompare.htmlOpen ↗

From the data available on Sandiway Fong's website, it looks like the aero efficiency (speed vs.
power input) of unfaired high-racers,

quasi-lowracers

Quoted message said:

and lowracer recumbents differs only slightly from each other; but

produces

Quoted message said:

a noticeable speed advantage over DF bikes (at a given power output).

Hard

Quoted message said:

shell fully faired recumbents, as one would imagine, really start to show off their superior aero
advantage in the upper extremes of speed (40mph+). Here is a chart excerpted from Mr. Fong's
website (I didn't see any copyright declarations, so I hope it's OK.)

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of 40
km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

The difference between DF/uprights and unfaired lowracers is significant; but the difference
between unfaired and fully-faired lowracers is just amazing. Yes, folks, according to this study,
that same 75 watts of power that produces ~10 mph on your hybrid upright bike would have you
screaming along at 25 mph in a fully-faired lowracer. Wow.

The difference in aero efficiency between an upright/DF racing bike and an unfaired high-racer
recumbent is about 23% at 25mph. From my observations riding alongside a Bacchetta Strada in fast
club rides, this seems about right. The Bacchetta owner in our local club, Bruce, is able to pull
a paceline longer than all but the very strongest DF riders (and at higher speeds). He's fresher
and much more animated at the end of the race - er,

I

Quoted message said:

mean ride ;-) - and continues chatting pleasantly at speeds that make the

DF

Quoted message said:

riders (including myself) hunker down and groan with pain. I pulled a

muscle

Quoted message said:

trying to keep up with Bruce this summer on my lovely new Soulcraft road bike. I could see that it
aggravated the competitive riders when Bruce

would

Quoted message said:

cruise up from the back at 28mph and pleasantly chat with them as he

slotted

Quoted message said:

into the lead to pull for a while. Bruce gets a kick out of it, for sure.

Once we get past the aero advantage issues, the next topic is riding position. Open vs. closed:
which is better for making power?Personally,

I'm

Quoted message said:

of the belief that a closed position is faster. I think I'm in good

company

Quoted message said:

here.

Then there's high BB vs. low BB. I've ridden them all, and I don't know which one is faster (if
any). I think once you get your legs out in front of you, it's all about the same. Any speed
advantages probably have more

to

Quoted message said:

do with cardiovascular advantages. Just a guess. Anybody have any good

data

Quoted message said:

on this topic?

Since I'm getting ready to buy a Velokraft carbon lowracer, I'm revisiting this topic. When my DF
riding buddies want to know why I ride a lowracer, it's nice to have some data to help make my
case. One look at all that beautiful carbon weave and I don't think there will be too many
dissenting voices.

-=Barry=-

2000 RANS Rocket Coming Soon: 2003 Velokraft

I read some of the "negative" commentary by the long distance rider about his relative speeds
ufaired bent vs. DF. When you consider he was riding an unfaired Tour Easy, it's no wonder he was a
bit disappointed. He could have picked a MUCH faster unfaired bike. Something like a Ti Aero would
give him the kind of performance he was looking for. Also, I wonder why he didn't use a fairing?
Some regulation for the rides he was doing? Put a Zzipper and sock on the TE, and he'd be a much
happier camper. It seems to me that one of the great thing about so many bent designs is that one
can mount a very effective fairing so easily. If you can't beat 'em, put on a fairing and a sock,
and beat 'em!

Scott

[email hidden] (Scott) wrote in message
news:<[email hidden]>...

Quoted message said:

Thanks, Barry. Very interesting!

Scott

"B. Sanders" <[email hidden]> wrote in message news:<L_oob.52992$9E1.241427@attbi_s52>...

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

<snip>

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed
of 40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

<snip>

Quoted message said:

Yes, folks, according to this study, that same 75 watts of power that produces ~10 mph on your
hybrid upright bike would have you screaming along at 25 mph in a fully-faired lowracer. Wow.

Doh!

Make that *42.8 mph*, not 25 mph. Can you believe these numbers? 42.8 mph for 75 watts of input?
That is incredible; but it does begin to explain how Sam Whittingham was able to power a faired
bike to 81+ mph on level ground. (remember: wind drag increases as the *cube* of velocity).

-Barry

B. Sanders said:

... Since I'm getting ready to buy a Velokraft carbon lowracer, I'm revisiting this topic. When my
DF riding buddies want to know why I ride a lowracer, it's nice to have some data to help make my
case. One look at all that beautiful carbon weave and I don't think there will be too many
dissenting voices.

Barry,

I am sure that your Velokraft will meet with approval on the Wednesday afternoon rides. 😉

Tom Sherman - Recumbent Curmudgeon

I just know my top cruising speed went up 10-15% from a carbon fiber racing upright to a dual
suspended steel semi-low racer. Interesting gain with the tail fairing though.

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

Here's an interesting web page which cites several experiments attempting

to

Quoted message said:

answer this question. It includes thoughtful narrative from several

riders

Quoted message said:

who offer sincere observations on the topic.

neci.nj.nec.comcompare.htmlOpen ↗

From the data available on Sandiway Fong's website, it looks like the aero efficiency (speed vs.
power input) of unfaired high-racers,

quasi-lowracers

Quoted message said:

and lowracer recumbents differs only slightly from each other; but

produces

Quoted message said:

a noticeable speed advantage over DF bikes (at a given power output).

Hard

Quoted message said:

shell fully faired recumbents, as one would imagine, really start to show off their superior aero
advantage in the upper extremes of speed (40mph+). Here is a chart excerpted from Mr. Fong's
website (I didn't see any copyright declarations, so I hope it's OK.)

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of 40
km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft material)
42.8 75 recumbent (very aerodynamic hard fairing)

The difference between DF/uprights and unfaired lowracers is significant; but the difference
between unfaired and fully-faired lowracers is just amazing. Yes, folks, according to this study,
that same 75 watts of power that produces ~10 mph on your hybrid upright bike would have you
screaming along at 25 mph in a fully-faired lowracer. Wow.

The difference in aero efficiency between an upright/DF racing bike and an unfaired high-racer
recumbent is about 23% at 25mph. From my observations riding alongside a Bacchetta Strada in fast
club rides, this seems about right. The Bacchetta owner in our local club, Bruce, is able to pull
a paceline longer than all but the very strongest DF riders (and at higher speeds). He's fresher
and much more animated at the end of the race - er,

I

Quoted message said:

mean ride ;-) - and continues chatting pleasantly at speeds that make the

DF

Quoted message said:

riders (including myself) hunker down and groan with pain. I pulled a

muscle

Quoted message said:

trying to keep up with Bruce this summer on my lovely new Soulcraft road bike. I could see that it
aggravated the competitive riders when Bruce

would

Quoted message said:

cruise up from the back at 28mph and pleasantly chat with them as he

slotted

Quoted message said:

into the lead to pull for a while. Bruce gets a kick out of it, for sure.

Once we get past the aero advantage issues, the next topic is riding position. Open vs. closed:
which is better for making power?Personally,

I'm

Quoted message said:

of the belief that a closed position is faster. I think I'm in good

company

Quoted message said:

here.

Then there's high BB vs. low BB. I've ridden them all, and I don't know which one is faster (if
any). I think once you get your legs out in front of you, it's all about the same. Any speed
advantages probably have more

to

Quoted message said:

do with cardiovascular advantages. Just a guess. Anybody have any good

data

Quoted message said:

on this topic?

Since I'm getting ready to buy a Velokraft carbon lowracer, I'm revisiting this topic. When my DF
riding buddies want to know why I ride a lowracer, it's nice to have some data to help make my
case. One look at all that beautiful carbon weave and I don't think there will be too many
dissenting voices.

-=Barry=-

2000 RANS Rocket Coming Soon: 2003 Velokraft

"Robert Haston" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I just know my top cruising speed went up 10-15% from a carbon fiber

racing

Quoted message said:

upright to a dual suspended steel semi-low racer.

Actually, I didn't experience that same increase in speed when going from an upright to a lowracer
recumbent, which was surprising. I bought an M5 Lowracer last year, with the expectation of
noticeable speed gains over all my other bikes (including a Ryan Vanguard LWB). The speed gains
didn't happen. Going into a strong headwind, the M5 Lowracer was incredibly aero-efficient. In every
other situation, the M5 was about the same or somewhat slower (that is, for a perceived output
power). That's not what I expected.

My hypothesis is that the M5 was certainly capable of being faster; but my muscles were producing
less power for a given perceived effort due to the high BB, which I wasn't accustomed to. So, I
worked just as hard, but produced less power on the M5. I know I can produce a *lot* of power on an
upright road bike in a sprint, and can hit speeds that I never even approached on the M5. With the
obvious differences in aero advantage between lowracers and DF's at those speeds (32 mph+), it's
clear that there was something amiss with my power production on the M5. This is what I'm curious
about with the Velokraft: Will I be able to produce power on it, and actually take advantage of its
superior aerodynamics? Or will I produce less power than I do on my upright/DF road bike, and fail
to see any significant speed benefits? This is the question that I intend to answer through
experimentation.

Quoted message said:

Interesting gain with the tail fairing though.

Yes, very interesting. Quite significant, and without impeding the practical use of the bike as a
full fairing could. A tail fairing would be a nice performance addition to a Velokraft; but it's a
shame to ruin those gorgeous, flowing lines. I'm already thinking about a full carbon fairing,
though, for special occasions, like fast club rides ;-) My neighbor across the alley is a carbon
fabricator (as a hobby). He produced carbon fiber wheelchairs for some Olympic athletes a while
back, and knows all about fabbing carbon in a garage with minimal expense and tools. A blown plastic
fairing (like the WISIL guys produce) would be another option. I'm curious to know what it's like to
cruise on a recumbent at 43 mph on level ground
:-)

-=Barry=-

Quoted message said:

"B. Sanders" <[email hidden]> wrote in message news:lLoob.49717$mZ5.311118@attbi_s54...

Quoted message said:

We all know that fully-faired recumbents own all of the human powered

speed

Quoted message said:

records. But what about unfaired recumbents vs. upright (DF) bikes?

Here's an interesting web page which cites several experiments

attempting

Quoted message said:

to

Quoted message said:

answer this question. It includes thoughtful narrative from several

riders

Quoted message said:

who offer sincere observations on the topic.

neci.nj.nec.comcompare.htmlOpen ↗

From the data available on Sandiway Fong's website, it looks like the

aero

Quoted message said:

Quoted message said:

efficiency (speed vs. power input) of unfaired high-racers,

quasi-lowracers

Quoted message said:

and lowracer recumbents differs only slightly from each other; but

produces

Quoted message said:

a noticeable speed advantage over DF bikes (at a given power output).

Hard

Quoted message said:

shell fully faired recumbents, as one would imagine, really start to

show

Quoted message said:

Quoted message said:

off their superior aero advantage in the upper extremes of speed

(40mph+).

Quoted message said:

Quoted message said:

Here is a chart excerpted from Mr. Fong's website (I didn't see any copyright declarations, so I
hope it's OK.)

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
19.8 469 road bike (touring position)
21.7 362 road bike (racy position)
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)
27.9 180 recumbent (seat hight 20 cm, with tail fairing)
31.6 135 recumbent (seat 20 cm, with full fairing, soft

material)

Quoted message said:

Quoted message said:

42.8 75 recumbent (very aerodynamic hard fairing)

The difference between DF/uprights and unfaired lowracers is

significant;

Quoted message said:

Quoted message said:

but the difference between unfaired and fully-faired lowracers is just amazing. Yes, folks,
according to this study, that same 75 watts of

power

Quoted message said:

Quoted message said:

that produces ~10 mph on your hybrid upright bike would have you

screaming

Quoted message said:

Quoted message said:

along at 25 mph in a fully-faired lowracer. Wow.

The difference in aero efficiency between an upright/DF racing bike and

an

Quoted message said:

Quoted message said:

unfaired high-racer recumbent is about 23% at 25mph. From my

observations

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riding alongside a Bacchetta Strada in fast club rides, this seems about right. The Bacchetta
owner in our local club, Bruce, is able to pull a paceline longer than all but the very
strongest DF riders (and at higher speeds). He's fresher and much more animated at the end of
the race -

er,

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I

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mean ride ;-) - and continues chatting pleasantly at speeds that make

the

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DF

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riders (including myself) hunker down and groan with pain. I pulled a

muscle

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trying to keep up with Bruce this summer on my lovely new Soulcraft road bike. I could see that
it aggravated the competitive riders when Bruce

would

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cruise up from the back at 28mph and pleasantly chat with them as he

slotted

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into the lead to pull for a while. Bruce gets a kick out of it, for

sure.

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Once we get past the aero advantage issues, the next topic is riding position. Open vs. closed:
which is better for making power?Personally,

I'm

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of the belief that a closed position is faster. I think I'm in good

company

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here.

Then there's high BB vs. low BB. I've ridden them all, and I don't know which one is faster (if
any). I think once you get your legs out in

front

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of you, it's all about the same. Any speed advantages probably have

more

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to

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do with cardiovascular advantages. Just a guess. Anybody have any good

data

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on this topic?

Since I'm getting ready to buy a Velokraft carbon lowracer, I'm

revisiting

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this topic. When my DF riding buddies want to know why I ride a

lowracer,

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it's nice to have some data to help make my case. One look at all that beautiful carbon weave
and I don't think there will be too many

dissenting

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voices.

-=Barry=-

2000 RANS Rocket Coming Soon: 2003 Velokraft

"B. Sanders" skrev

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Yes, very interesting. Quite significant, and without impeding the practical use of the bike as a
full fairing could. A tail fairing would be a nice performance addition to a Velokraft; but it's a
shame to ruin those gorgeous, flowing lines.

Ah ruin schmuin ;o)

community.webshots.com95148217fwrVirOpen ↗

M.

This chart clearly shows, as I have always suspected, that low racers are more efficient than high
racers, regardless of rolling resistance, which only seems to be significant at low speeds. They
should also be safer, turn better, and require less truing, although more frequent tire
replacement. Why then, have high racers such as bacchetta and Volae gained such a following? George
Reynolds went from his 20/20 to a 700/20 and now to a dual 700, and he certainly knows what he is
doing. I am confused!

--

Joel Wilson Fort Lauderdale
=========================================
Proud 2 B a pioneering satellite radio subscriber AI4I is always on the trailing edge of technology
=========================================

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of 40
km/h (~25mph)

V(mph) P(W) Bike Description
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)

"ai4i" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

This chart clearly shows, as I have always suspected, that low racers are more efficient than high
racers, regardless of rolling resistance, which only seems to be significant at low speeds. They
should also be safer,

turn

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better, and require less truing, although more frequent tire replacement. Why then, have high
racers such as bacchetta and Volae gained such a following? George Reynolds went from his 20/20 to
a 700/20 and now to a dual 700, and he certainly knows what he is doing. I am confused!

You're right; but there are several factors that you didn't list:

Sociability and Physical Stature High racers are taller than most recumbents, putting the rider at
the correct height for socializing with DF road bike riders. This makes high racers more acceptable
for riding in pace lines [with hypercompetitive males], where physical stature establishes
dominance.

Visibility in Traffic High racers are taller and more visible than lowracers. Visibility is
absolutely crucial for safety when riding along roads populated with cars (which means pretty much
everywhere). Lowracers, and tadpole trikes, are very low and not nearly as visible to tall vehicles
such as SUV's and 18-wheelers. There's also the psychological factor of sitting *below* the bumper
height of the SUV's and big trucks with which you are sharing the road. It's not a comfortable
feeling. We are programmed at the core of our
psyche to feel unsafe when huge, tall, loud, fast, heavy objects speed toward us.

Limited Steering and Steep Learning Curve Though not all lowracers exhibit limited steering range,
many do. My M5 Lowracer was a beast to get used to, with extremely limited steering. I fell more
times on that M5 in 3 months than I have on all other bikes combined in the past 10 years (no
exaggeration). The tiller steering, extreme laid-back seat angle and limited steering combined to
give the M5 quite a steep learning curve. In fact, after a week of constant failures, I almost sold
the M5 in disgust; but with the help of folks on this NG, I kept at it, and learned to really enjoy
the ride. Ultimately, I sold the M5 because (a) I was poor and neede the money, and (b) it is known
to be a beast, and I wanted to try something else that was easier to ride.

Balance Stability Taller bikes are more stable. Think of a bike as an inverted pendulum. The taller
it is, the more time the rider has to correct his balance, which makes the bike more forgiving of
errors and more stable in general. Anyone who has tried to learn how to ride a lowracer knows how
squirrelly they are. You need quick reflexes to learn to ride them well. Taller bikes, in general,
are much more forgiving; particularly with recumbents, since steering is by far the largest factor
for maintaining balance.

I'm not surprised at the popularity of high racers. I don't think it's really about speed, since
lowracers are faster. It's because of the much shallower learning curve, taller stature, better
stability and better visibility of high racers. And high racers are still fast bikes. Look at the
chart again. The difference in aero efficiency between high racers and low racers is very slight. Of
course, as speed increases, the differences become magnified; but most riders never those high
speeds anyway, except on downhill runs.

-=Barry=-

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--

Joel Wilson Fort Lauderdale
=========================================
Proud 2 B a pioneering satellite radio subscriber AI4I is always on the trailing edge of
technology
=========================================

Quoted message said:

V = velocity at a constant power output of 250 W P = power needed to maintain constant speed of
40 km/h (~25mph)

V(mph) P(W) Bike Description
23.9 277 recumbent (seat hight 60 cm)
24.5 259 recumbent (seat hight 40 cm)
25.4 234 recumbent (seat hight 20 cm = low racer)

Joel,

Quoted message said:

This chart clearly shows, as I have always suspected, that low racers are more efficient than high
racers, regardless of rolling resistance, which only seems to be significant at low speeds.

Quoted message said:

Why then, have high racers...gained such a following? George Reynolds....... certainly knows what
he is doing. I am confused!

One: Most of us don't ride at anything like 250 watts all the time. Tables in the Second
International Human Powered Vehicle Scientific Symposium Proceedings show that average healthy
humans can produce 250 watts for ~50 minutes. First class athletes can do so for more than 8 hours!
At more realistic power outputs for average riders, the mechanical and rolling loses become more
important, and the slight aero gains (if any) less so.

Two: Those figures were obtained on a level, smooth velodrome. The same reference mentioned above
shows that at a 5% grade the aero advantage of even a 40# full streamliner lost to a standard
upright road bike. Start climbing on chip sealed, real roads, and that 250 watts will not get you
into the speed range where a slight aero advantage can make up for greater weight, rolling
resistance, and drivetrain loses.

Now the 200# Clydesdales, who put out 300 watts for 8 hours on an 20# single chainring racing
lowracer, can tell me that is not THEIR experience. All I can say is more power to them. :-)

Warren

ai4i said:

This chart clearly shows, as I have always suspected, that low racers are more efficient than high
racers, regardless of rolling resistance

Are you sure the tall bikes in the study are highracers? I don't know which bikes they used, but the
study was done in the Netherlands and most tall Dutch bikes are touring bikes, not racing bikes.
They tend to have lower BB (relative to seat) and more upright seatback than lowracers, as far as I
can tell from the catalogs. Try going to the M5 homepage and comparing a 26/26 and a Lowracer.

Ken Kobayashi [email hidden] solarwww.mtk.nao.ac.jppersonalOpen ↗

B. Sanders said:

... Anyone who has tried to learn how to ride a lowracer knows how squirrelly they are. You need
quick reflexes to learn to ride them well....

It took me less than half a lap at the indoor test ride area at CABDA 2000 to adjust to riding an
Earth Cycles Sunset Lowracer [TM]. [1] I believe that steering geometry is much more important that
seat height for handling qualities.

[1] And anyone who thinks that this was due to superior reflexes or balance never saw my first
unsuccessful attempt to ride a 1998 Vision R-40 SWB USS.

Tom Sherman - Recumbent Curmudgeon

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Are you sure the tall bikes in the study are highracers? I don't know which bikes they used, but
the study was done in the Netherlands and most tall Dutch bikes are touring bikes, not racing
bikes. They tend to have lower BB (relative to seat) and more upright seatback than lowracers, as
far as I can tell from the catalogs. Try going to the M5 homepage and comparing a 26/26 and a
Lowracer.

you're right big wheels optima, for example, are not sporty at all ;-) bacchetta aero and optima
condor are two really different bikes, the condor is a steel bike, strong and perfect to touring all
around... the aero is a speed daemon ;-) matteo