HPV/Tandem questions (gonna be long)

  • Thread starter Phil, Squid-in-Training
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P

Phil, Squid-in-Training

Guest
Okay so I'm doing a HPV project at my university. We're looking for several
things:

1. Fast (and efficient)
2. Big wheels (to go fast)
3. Tandem (to go fast)
4. Strong (so it doesn't fall apart)
5. Somewhat light (less than 100lb)
6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
the bike)

There's a bunch more but I'm going to be polling the NG a whole lot in the
next couple days.

My questions:
1. What kind of bike should it be? Are bents faster overall? Is semi-bent
a good idea? The riders will be experienced riders that are used to
traditional frames.
2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?
3. What kind of designs employ 700c wheels front and rear on a tandem bent?
How can we get that to work with shorter riders?

--
Phil, Squid-in-Training
 
J

JeffWills

Guest
Phil, Squid-in-Training wrote:
> Okay so I'm doing a HPV project at my university. We're looking for several
> things:
>
> 1. Fast (and efficient)
> 2. Big wheels (to go fast)
> 3. Tandem (to go fast)
> 4. Strong (so it doesn't fall apart)
> 5. Somewhat light (less than 100lb)
> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
> the bike)
>
> There's a bunch more but I'm going to be polling the NG a whole lot in the
> next couple days.
>
> My questions:
> 1. What kind of bike should it be? Are bents faster overall? Is semi-bent
> a good idea? The riders will be experienced riders that are used to
> traditional frames.


In general, tandems and 'bents share the same weaknesses, primarily
related to adaptation time of well-trained single-bike riders. Two fast
single-bike riders may not make a fast tandem team. Fast upright riders
do not always become fast recumbent riders. Getting two riders to
coordinate their efforts is a sticky problem, and part of the reason
why my wife and I ride individual singles and not a tandem. Similarly,
recumbents are not always faster than the same rider on an upright.
"Recumbent" can mean many different designs, from a city-oriented Bikee
to a laid-out lowracer.

It's probably best to build a good, reliable bike *quickly*, then allow
your riders some time to adapt to the different riding position.


> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?


Your frame design will dictate tubing size.

> 3. What kind of designs employ 700c wheels front and rear on a tandem bent?


A good possibility is a two-wheel-drive back-to-back bike, similar to
the Wood Brothers' machine:
http://www.ohpv.org/albums/pir2005/photos/pages/IMGP4696.htm
Fitting a 700C wheel between the rider's legs is tough, but I've seen
it done. There's not much room for steering lock, though. (The Wood
machine uses 24" wheels.) Otherwise, you may be thinking of a "more
conventional" tandem recumbent like an M5:
http://www.m5-ligfietsen.com/main.php?sNewPage=Tandem

> How can we get that to work with shorter riders?


Rotator has built dual-700C FWD single recumbents with the front wheel
well in front of the cranks. That's a long bike- a tandem would be much
longer.

Jeff
 
M

Michael Press

Guest
In article <[email protected]>,
"Phil, Squid-in-Training"
<[email protected]> wrote:

> Okay so I'm doing a HPV project at my university. We're looking for several
> things:
>
> 1. Fast (and efficient)
> 2. Big wheels (to go fast)
> 3. Tandem (to go fast)
> 4. Strong (so it doesn't fall apart)
> 5. Somewhat light (less than 100lb)
> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
> the bike)
>
> There's a bunch more but I'm going to be polling the NG a whole lot in the
> next couple days.
>
> My questions:
> 1. What kind of bike should it be? Are bents faster overall? Is semi-bent
> a good idea? The riders will be experienced riders that are used to
> traditional frames.
> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?
> 3. What kind of designs employ 700c wheels front and rear on a tandem bent?
> How can we get that to work with shorter riders?


How about designing fairings for existing diamond frame
bicycles. How much faster can you get it to go?

--
Michael Press
 
N

Nate Knutson

Guest
Phil, Squid-in-Training wrote:
> Okay so I'm doing a HPV project at my university. We're looking for several
> things:
>
> 1. Fast (and efficient)
> 2. Big wheels (to go fast)
> 3. Tandem (to go fast)
> 4. Strong (so it doesn't fall apart)
> 5. Somewhat light (less than 100lb)
> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
> the bike)
>
> There's a bunch more but I'm going to be polling the NG a whole lot in the
> next couple days.
>
> My questions:
> 1. What kind of bike should it be? Are bents faster overall? Is semi-bent
> a good idea? The riders will be experienced riders that are used to
> traditional frames.
> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?
> 3. What kind of designs employ 700c wheels front and rear on a tandem bent?
> How can we get that to work with shorter riders?


Without getting too far into debatable stuff I know little about, I
think it's probably pretty important that you specify what kind of
riding this is going be used for - racing, transportation, etc?

I don't think there's any way of knowing what tube size to order until
you have your design.

You may want to look at da Vinci tandem cranks. These have 3 sets of
pedals to be adaptable for different riders. They're cool because the
shortest setting is something like 155 or 160mm, shorter than
conventional cranks come but probably about what really short people
should be riding. This is a huge debate obviously, especially since
it's a recumbent. Also, they're pricey and high end, so don't know how
well that fits in.

A good friend of mine owns a RANS Screamer that he and another friend
rode across the country. He's 6'-ish and she's 5'2"-ish, and one of the
reasons they chose this frame is because it seemed to be a design that
let both of them captain. They never got around to trying this out on
their trip, but it seems to make sense given the frame's geometry, so
you may want to investigate the design.

One final thing - be sure to think carefully about clearance issues
regarding the front wheel, whatever body parts happen to be in the
vicinity, and the chain if the design you settle on features a boom. I
imagine this getting tricky on recumbent bents made for all out speed
featuring 700's.
 
J

JeffWills

Guest
Michael Press wrote:

>
> How about designing fairings for existing diamond frame
> bicycles. How much faster can you get it to go?
>


This was done in the mid '70's, with a streamlined Teledyne Titan
ridden by Ron Skarin. I think they reached speeds in the mid-40mph
range. Moulton bikes were also encased in full fairings

One problem with a full fairing for an upright is that it's got so much
side area that it's really susceptible to crosswinds. The vehicle ends
up being really difficult to control.

(One consequence of a large-area fairing: it'll produce a lot of lift.
Eyewitness accounts told of faired uprights taking flight when they
fell over at speed. This is the hard way to accomplish human-powered
flight.

Jeff
 
W

Werehatrack

Guest
On Wed, 1 Mar 2006 00:12:48 -0500, "Phil, Squid-in-Training"
<[email protected]> wrote:

>Okay so I'm doing a HPV project at my university. We're looking for several
>things:


A concept project vehicle, not a production-intended unit for use by
an average rider? Been done, countless times. You have much research
to do into prior attempts, grasshopper.

>1. Fast (and efficient)


Been done, still being done, evidence abounds on the floor at any bike
shop, for reasonable definitions of "efficient".

>2. Big wheels (to go fast)


Not a needed criteria unless you're aiming for speeds over 100mph,
which is also not a useful target. Existing art indicates that for
common human-achievable speeds, current common bike wheel sizes are
sometimes larger than really needed.

>3. Tandem (to go fast)


Not necessarily relevant. Two engines typically don't achieve much
more than one in this arena.

>4. Strong (so it doesn't fall apart)


Well, duh, but you haven't stated what kind of riding parameters are
proposed; for smooth level pavement, this is trivially easy.

>5. Somewhat light (less than 100lb)


Shoot for under 35 lbs for a tandem, or under 20 lbs for a single,
with full fairing, and you'll get some attention. Under 100 lbs is a
criterion that was bettered before 1890 even for a tandem bike.

>6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
>the bike)


Adjustable frame? Possible, but introduces a great deal of fragility
and complexity to the design which impedes efficiency.

>There's a bunch more but I'm going to be polling the NG a whole lot in the
>next couple days.
>
>My questions:
>1. What kind of bike should it be? Are bents faster overall? Is semi-bent
>a good idea? The riders will be experienced riders that are used to
>traditional frames.
>2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?
>3. What kind of designs employ 700c wheels front and rear on a tandem bent?
>How can we get that to work with shorter riders?


You need to cruise the sites that detail the history of the HPV
projects that have come before, and then hit the books in the
libraries and archives of the enthusiast groups and competition
arbiters to see what has already been achieved. Omit this groundwork,
and you are committing to making the same mistakes that have been made
and overcome in the past.

The modern bicycle is a mature product of a great deal of practical
experimentation over more than a century of time. Extreme variants
designed for special tasks (raw speed, speed with duration, raw speed
without regard to wind resistance, etc) have been made many times. A
bicycle was used to break the 100mph barrier (riding in a moving
enclosure) more than 50 years ago. Bicycles capable of allowing a
single rider to exceed 70mph regularly in open air have been built a
number of times. The bikes used in the Race Across America, an
extreme endurance race, are nothing as exotic as you might suppose.

You'll note the conspicuous lack of URLs and cites in the statements
above. This is supposed to be *your* research project, not mine. In
my opinion, the criteria you have set forward demonstrate that you've
skipped the essential first step in any such project; seeing where the
rest of the world has already taken this, and finding out what worked,
and what still needed more work. Materials change, tech changes,
people with new ideas come along...there's still plenty of opportunity
for innovation and improvement in bike design. If you are not to
simply repeat the mistakes of the past, however, you need to start
with an understanding of it, and then devise your specs to take
advantage of what you know at that point.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
 
J

JeffWills

Guest
Werehatrack wrote:
<snip>
>
> You'll note the conspicuous lack of URLs and cites in the statements
> above. This is supposed to be *your* research project, not mine. In
> my opinion, the criteria you have set forward demonstrate that you've
> skipped the essential first step in any such project; seeing where the
> rest of the world has already taken this, and finding out what worked,
> and what still needed more work.


Well, I'll take pity on poor Phil and provide a couple URLs for his
perusal, in addition to what I've supplied already:
The Cal Berkeley Bearacuda, a tandem, fully-faired, BTB AWD HPV:
http://calhpv.berkeley.edu/Pics/PicIndex.html
Tom Traylor's built a couple BTB recumbent tandems:
http://traylorfwd.home.mindspring.com/back-2-back_article.html
Matt Weaver's Speed101 site:
http://www.speed101.com/
WISIL & MARS HPVers- lots of practical design and building techniques:
http://www.recumbents.com/wisil.htm
http://www.recumbents.com/mars/
There's a couple discussion boards on the Bentrideronline site that you
should look at:
http://www.bentrideronline.com/messageboard/forumdisplay.php?f=12
http://www.bentrideronline.com/messageboard/forumdisplay.php?f=7
http://www.bentrideronline.com/messageboard/forumdisplay.php?f=14

Jeff
 
D

Dave Larrington

Guest
In article <[email protected]>, Phil, Squid-in-Training
([email protected]) wrote:
> Okay so I'm doing a HPV project at my university. We're looking for several
> things:
>
> 1. Fast (and efficient)
> 2. Big wheels (to go fast)
> 3. Tandem (to go fast)
> 4. Strong (so it doesn't fall apart)
> 5. Somewhat light (less than 100lb)
> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have to ride
> the bike)
>
> There's a bunch more but I'm going to be polling the NG a whole lot in the
> next couple days.
>
> My questions:
> 1. What kind of bike should it be? Are bents faster overall? Is semi-bent
> a good idea? The riders will be experienced riders that are used to
> traditional frames.
> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1 1/8? 2?
> 3. What kind of designs employ 700c wheels front and rear on a tandem bent?
> How can we get that to work with shorter riders?


I would suggest contemplating something along the lines of the Flevo
Rug-aan-Rug:

<URL:http://www.legslarry.beerdrinkers.co.uk/images/pix/WHPVC2001/Martin
LeVoi/MarVoi003.jpg>

That one's on dual 559s and was built with long Dutchmen in mind. Did
almost 28 mph for two hours round the Goodwood circuit during the 2001
Worlds in the hands of Allert Jacobs & John Poot. Allert & John
subsequently built a dual 406 version, as they were fed up with dragging
the assembled solos round in race after race, and I believe the smaller-
wheeled version did indeed turn out to be faster.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Do not top-post like a Cretinous Foul-Yob fit only for Stoning.
 
P

Phil, Squid-in-Training

Guest
Dave Larrington wrote:
> In article <[email protected]>, Phil, Squid-in-Training
> ([email protected]) wrote:
>> Okay so I'm doing a HPV project at my university. We're looking for
>> several things:
>>
>> 1. Fast (and efficient)
>> 2. Big wheels (to go fast)
>> 3. Tandem (to go fast)
>> 4. Strong (so it doesn't fall apart)
>> 5. Somewhat light (less than 100lb)
>> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have
>> to ride the bike)
>>
>> There's a bunch more but I'm going to be polling the NG a whole lot
>> in the next couple days.
>>
>> My questions:
>> 1. What kind of bike should it be? Are bents faster overall? Is
>> semi-bent a good idea? The riders will be experienced riders that
>> are used to traditional frames.
>> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1
>> 1/8? 2?
>> 3. What kind of designs employ 700c wheels front and rear on a
>> tandem bent? How can we get that to work with shorter riders?

>
> I would suggest contemplating something along the lines of the Flevo
> Rug-aan-Rug:
>
> <URL:http://www.legslarry.beerdrinkers.co.uk/images/pix/WHPVC2001/Martin
> LeVoi/MarVoi003.jpg>
>
> That one's on dual 559s and was built with long Dutchmen in mind. Did
> almost 28 mph for two hours round the Goodwood circuit during the 2001
> Worlds in the hands of Allert Jacobs & John Poot. Allert & John
> subsequently built a dual 406 version, as they were fed up with
> dragging the assembled solos round in race after race, and I believe
> the smaller- wheeled version did indeed turn out to be faster.


Interesting... I wonder why that was.
--
Phil, Squid-in-Training
 
D

Dave Larrington

Guest
In article <[email protected]>, Phil, Squid-in-Training
([email protected]) wrote:
> Dave Larrington wrote:
> > In article <[email protected]>, Phil, Squid-in-Training
> > ([email protected]) wrote:
> >> Okay so I'm doing a HPV project at my university. We're looking for
> >> several things:
> >>
> >> 1. Fast (and efficient)
> >> 2. Big wheels (to go fast)
> >> 3. Tandem (to go fast)
> >> 4. Strong (so it doesn't fall apart)
> >> 5. Somewhat light (less than 100lb)
> >> 6. Modular (we have riders at 5'5" and riders at 6'2" that will have
> >> to ride the bike)
> >>
> >> There's a bunch more but I'm going to be polling the NG a whole lot
> >> in the next couple days.
> >>
> >> My questions:
> >> 1. What kind of bike should it be? Are bents faster overall? Is
> >> semi-bent a good idea? The riders will be experienced riders that
> >> are used to traditional frames.
> >> 2. What kind of tubing diameters should we be ordering? 1 1/4? 1
> >> 1/8? 2?
> >> 3. What kind of designs employ 700c wheels front and rear on a
> >> tandem bent? How can we get that to work with shorter riders?

> >
> > I would suggest contemplating something along the lines of the Flevo
> > Rug-aan-Rug:
> >
> > <URL:http://www.legslarry.beerdrinkers.co.uk/images/pix/WHPVC2001/Martin
> > LeVoi/MarVoi003.jpg>
> >
> > That one's on dual 559s and was built with long Dutchmen in mind. Did
> > almost 28 mph for two hours round the Goodwood circuit during the 2001
> > Worlds in the hands of Allert Jacobs & John Poot. Allert & John
> > subsequently built a dual 406 version, as they were fed up with
> > dragging the assembled solos round in race after race, and I believe
> > the smaller- wheeled version did indeed turn out to be faster.

>
> Interesting... I wonder why that was.


Less frontal area and, provided decent tyres are used, very little more
rolling resistance, would be my guess. I wouldn't use something like a
406 Schwalbe Stelvio or Conti GP for regular road use on a tandem, but
subject to frequent inspection they'd be OK for racing.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
I'm just a primitive creature of the heath, so pardon my savage
ignorance.
 
B

Bill Patterson

Guest
Dave Larrington wrote:
and I believe
>>>the smaller- wheeled version did indeed turn out to be faster.

>>
>>Interesting... I wonder why that was.

>
>
> Less frontal area and, provided decent tyres are used, very little more
> rolling resistance, would be my guess. I wouldn't use something like a
> 406 Schwalbe Stelvio or Conti GP for regular road use on a tandem, but
> subject to frequent inspection they'd be OK for racing.
>


At high speed the aerodynamic drag is so large that the possibility of a
little higher rolling resistance is insignificant. Small tires cause
less aerodynamic drag and that power required goes up as the cube of the
velocity.

Tandems are great, just remember the ride is about her, not the bike or
the competition.
--
See bikes at: http://home.earthlink.net/~wm.patterson/index.html

See bikes and the first human powered helicopter at:

http://www.calpoly.edu/~wpatters/

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