looking for ski/bike roof rack help

[G.T.]

"Doki" <[email protected]> wrote in message
news:[email protected]...
>
>
> p e t e f a g e r l i n wrote:
> >>>> On Sat, 13 Mar 2004 21:27:40 -0000, "Doki"
> >>>> <[email protected]> wrote:
> >>>>
> >>>>> Why not just take the wheels off and chuck the bikes
> >>>>> in the boot (trunk)? Bike racks do very bad things
> >>>>> to your cars aerodynamics,
> >>>>
> >>>> That is really dependent upon the aerodynamics of the
> >>>> vehicle.
> >>>>
> >>>> Roof racks don't have to have that great an impact,
> >>>> let alone do "very bad things" to a vehicle's
> >>>> aerodynamics.
> >>>
> >>> The racks themselves aren't so bad. But they'll get a
> >>> lot worse with a couple of bikes strapped to them .
> >
> > Of course they'll get worse.
> >
> > But that doesn't mean they have to do "very bad things"
> > to a vehicle's aerodynamics.
>
> What I've read suggests fuel consumption can rise by 20 or
> 30% with bikes strapped to the roof of your car. Obviously
> there'll be more impact here where everyone drives at 70
> much of time, whilst in America the limit on motorway /
> dual carriageway equivalent roads is 55mph. I'm not
> suggesting that they'll generate a load of lift, but that
> they'll increase drag.
>

The very reason I throw my bike inside when there's only
one of me.

Greg

 

[Shawn Curry]

Doki wrote:

> p e t e f a g e r l i n wrote:
>
>>>>>On Sat, 13 Mar 2004 21:27:40 -0000, "Doki"
>>>>><[email protected]> wrote:
>>>>>
>>>>>
>>>>>>Why not just take the wheels off and chuck the bikes
>>>>>>in the boot (trunk)? Bike racks do very bad things to
>>>>>>your cars aerodynamics,
>>>>>
>>>>>That is really dependent upon the aerodynamics of the
>>>>>vehicle.
>>>>>
>>>>>Roof racks don't have to have that great an impact, let
>>>>>alone do "very bad things" to a vehicle's aerodynamics.
>>>>
>>>>The racks themselves aren't so bad. But they'll get a
>>>>lot worse with a couple of bikes strapped to them .
>>
>>Of course they'll get worse.
>>
>>But that doesn't mean they have to do "very bad things" to
>>a vehicle's aerodynamics.
>
>
> What I've read suggests fuel consumption can rise by 20 or
> 30% with bikes strapped to the roof of your car. Obviously
> there'll be more impact here where everyone drives at 70
> much of time, whilst in America the limit on motorway /
> dual carriageway equivalent roads is 55mph. I'm not
> suggesting that they'll generate a load of lift, but that
> they'll increase drag.
>
ROTFL That's funny. Is that what that sign with the big 55
means? BTW, that's old news. Rural two lane highways
around here (Colorado) have 65 mph limits. I drive them at
75-80 mph. Yeah, gimme a break, I've slowed down since I
hit 40 ;-)

Cheers, Shawn

 

[Dan Volker]

"Doki" <[email protected]> wrote in message
news:[email protected]...
>
>
> p e t e f a g e r l i n wrote:
> >>>> On Sat, 13 Mar 2004 21:27:40 -0000, "Doki"
> >>>> <[email protected]> wrote:
> >>>>
> >>>>> Why not just take the wheels off and chuck the bikes
> >>>>> in the boot (trunk)? Bike racks do very bad things
> >>>>> to your cars aerodynamics,
> >>>>
> >>>> That is really dependent upon the aerodynamics of the
> >>>> vehicle.
> >>>>
> >>>> Roof racks don't have to have that great an impact,
> >>>> let alone do "very bad things" to a vehicle's
> >>>> aerodynamics.
> >>>
> >>> The racks themselves aren't so bad. But they'll get a
> >>> lot worse with a couple of bikes strapped to them .
> >
> > Of course they'll get worse.
> >
> > But that doesn't mean they have to do "very bad things"
> > to a vehicle's aerodynamics.
>
> What I've read suggests fuel consumption can rise by 20 or
> 30% with bikes strapped to the roof of your car. Obviously
> there'll be more impact here where everyone drives at 70
> much of time, whilst in America the limit on motorway /
> dual carriageway equivalent roads is 55mph. I'm not
> suggesting that they'll generate a load of lift, but that
> they'll increase drag.

I drive a Honda Insight, the gas/electric hybrid ...With
just one mountain bike inside I can usually get about 50
miles per gallon at 70 mph ( as good as 60 mpg with a good
tail wind, or as bad as 45 mpg with a stiff head wind). At
90 mph, milage drops to about 40 mpg. If I put my Saris
Bones rack on the back with 2 mountain bikes ( with much
less drag than a roof rack), the mpg at 70 mph will drop to
about 30mpg, due to the bikes being exposed a little where
they stick out on each side, and the interuption of the
aerodynamics passing over the car.

What I'd like is a rack that comes out of a reciever hitch
in the back, but has the bikes facing front instead of
sideways, with the front wheel off--front wheels could go
inside. This should get the bikes down lower, more in the
draft of the car, and no longer exposed on either side of
the car. So far I have not heard of any such rack, but if it
existed, it should be more fuel efficient for any car. It
might need a brake light mounted on the end exposed to cars
behind you....no big deal. I may have this fabricated if I
can't find anything like this already. Anyone heard of a
rack like this ? Dan V

 

[Craig Brossman]

Shawn Curry wrote:

> ROTFL That's funny. Is that what that sign with the big 55
> means? BTW, that's old news. Rural two lane highways
> around here (Colorado) have 65 mph limits. I drive them at
> 75-80 mph. Yeah, gimme a break, I've slowed down since I
> hit 40 ;-)
>
> Cheers, Shawn

55 thru the San Luis Valley? Sometimes I set the
cruise control to 70, climb in the back, and take a
nap for a while.

--
Craig Brossman, Durango Colorado (remove ".nospam" to reply)

 

[Craig Brossman]

Dan Volker wrote:

> What I'd like is a rack that comes out of a reciever hitch
> in the back, but has the bikes facing front instead of
> sideways, with the front wheel off--front wheels could go
> inside. This should get the bikes down lower, more in the
> draft of the car, and no longer exposed on either side of
> the car.
>

Here you go, I do not own one.

http://www.draftmaster.com/
--
Craig Brossman, Durango Colorado (remove ".nospam" to reply)

 

[Dan Volker]

"Craig Brossman" <[email protected]> wrote in message
news:[email protected]...
> Dan Volker wrote:
>
>
> > What I'd like is a rack that comes out of a reciever
> > hitch in the back,
but
> > has the bikes facing front instead of sideways, with the
> > front wheel off--front wheels could go inside. This
> > should get the bikes down lower, more in the draft of
> > the car, and no longer exposed on either side of
the
> > car.
> >
>
> Here you go, I do not own one.
>
> http://www.draftmaster.com/
> --
Thanks, I looked at the site, and just e-mailed them my
request for a slightly more horizontal version of this, that
would allow the bike to draft the Insight.

Dan V

 

[Doki]

Penny S wrote:
> Doki ran this through spell check:

>> What I've read suggests fuel consumption can rise by 20
>> or 30% with bikes strapped to the roof of your car.
>> Obviously there'll be more impact here where everyone
>> drives at 70 much of time, whilst in America the limit on
>> motorway / dual carriageway equivalent roads is 55mph.
>> I'm not suggesting that they'll generate a load of lift,
>> but that they'll increase drag.
>
> heh, heh, I don't think the "limit' means a whole lot to
> some of us. Anyway, I think you'd better post some
> aerodymic/drag FACTS pretty soon.

There's no way in hell that I'm booking wind tunnell time to
settle an argument on usenet . Just do a google for "bike
rack fuel consumption" and I'm sure you'll get some figures.

 

[Penny S]

Doki ran this through spell check:
> I was under the impression that the max speed limit on
> lots of roads is 55. I had heard of some experiments with
> removal of speed limits though.

You are behind the times and misinformed. While for many
years the Federal limit was 55 ( like anyone paid attention
to that once you are out in the boonies) it was raised to 65
and then 70 on the interstates several years ago. Montana
does not have a speed limit per se, but how fast you can go
before you are ticketed it totally up to the local law
enforment.

Anyone remember the "wasting energy" speeding tickets
in Nevada?

Penny

 

[G.T.]

"Doki" <[email protected]> wrote in message
news:[email protected]...
>
>
> p e t e f a g e r l i n wrote:
> > "Doki" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >> What I've read suggests fuel consumption can rise by 20
> >> or 30% with bikes strapped to the roof of your car.
> >> Obviously there'll be more impact here where everyone
> >> drives at 70 much of time, whilst in America the limit
> >> on motorway / dual carriageway equivalent roads is
> >> 55mph. I'm not suggesting that they'll generate a load
> >> of lift, but that they'll increase drag.
> >
> > ROTFLMAO!
> >
> > You really think that because some roads are signed at
> > 55 people only drive 55 in the US? BTW, Many roads in
> > the US are signed at 70+ mph.
>
> I was under the impression that the max speed limit on
> lots of roads is
55.
>

In California on two lane roads it's 55mph. On freeways the
max I've seen is 75.

> I had heard of some experiments with removal of speed
> limits though.
>

Just in Montana, I believe.

Greg

 

[Doki]

Penny S wrote:
> Doki ran this through spell check:
>> I was under the impression that the max speed limit on
>> lots of roads is 55. I had heard of some experiments with
>> removal of speed limits though.
>
> You are behind the times and misinformed.

I do live in the UK, and have never driven in the US. The
only info I get on US speed limits is from seeing signs and
people getting pulled over in films.

> While for many years the Federal limit was 55 ( like
> anyone paid attention to that once you are out in the
> boonies) it was raised to 65 and then 70 on the
> interstates several years ago. Montana does not have a
> speed limit per se, but how fast you can go before you are
> ticketed it totally up to the local law enforment.

I see.

> Anyone remember the "wasting energy" speeding tickets
> in Nevada?

That's how they introduced speed limits here. During the
fuel crisis of the 70s, speed limits were introduced on
motorways and country roads, on the grounds of saving fuel
then were never removed. The Isle of Man is an exception,
and still has no speed limit outside of town.

 

[Craig Brossman]

Penny S wrote:

> Anyone remember the "wasting energy" speeding tickets
> in Nevada?
>
>
> Penny
>
>

Got some sort of "environmental" ticket in Montana 10 years
ago, $10 on the spot.

--
Craig Brossman, Durango Colorado (remove ".nospam" to reply)

 

[Bomba]

On Wed, 17 Mar 2004 16:45:19 +0000, Doki wrote:

> That's how they introduced speed limits here. During the
> fuel crisis of the 70s, speed limits were introduced on
> motorways and country roads, on the grounds of saving fuel
> then were never removed.

The speed limit was introduced much earlier than that.
Back in the 60's, IIRC, due to a series of accidents in
poor weather and AC Cars testing their Cobras at 190mph
up the M1.

The Isle of Man is an
> exception, and still has no speed limit outside of town.

Then there's the German autobahns

 

[P E T E F A G E]

On Wed, 17 Mar 2004 16:15:26 -0000, "Doki" <[email protected]>
wrote:

>
>
>p e t e f a g e r l i n wrote:

>> You really think that because some roads are signed at 55
>> people only drive 55 in the US? BTW, Many roads in the US
>> are signed at 70+ mph.
>
>I was under the impression that the max speed limit on lots
>of roads is 55. I had heard of some experiments with
>removal of speed limits though.

You are sorely mistaken regarding the speed limits as well
as mistaken if you think that folks obey them regularly on
the highways.

>> My comments relate to driving at high speeds where the
>> additional wind resistance doesn't make that great a
>> difference, for some vehicles, based upon my experience.
>
>Some vehicles = ones that aren't particularly aerodynamic
>to start with?

Nope. Some vehicles that are VERY aerodynamic to start with,
as well as some that are less aerodynamic to start with.

 

[Doki]

P e t e F a g e r l i n wrote:
> On Wed, 17 Mar 2004 16:15:26 -0000, "Doki"
> <[email protected]> wrote:
>
>>
>>
>> p e t e f a g e r l i n wrote:
>
>>> You really think that because some roads are signed at
>>> 55 people only drive 55 in the US? BTW, Many roads in
>>> the US are signed at 70+ mph.
>>
>> I was under the impression that the max speed limit on
>> lots of roads is 55. I had heard of some experiments with
>> removal of speed limits though.
>
> You are sorely mistaken regarding the speed limits as well
> as mistaken if you think that folks obey them regularly on
> the highways.

Fair enough.

>>> My comments relate to driving at high speeds where the
>>> additional wind resistance doesn't make that great a
>>> difference, for some vehicles, based upon my experience.
>>
>> Some vehicles = ones that aren't particularly aerodynamic
>> to start with?
>
> Nope. Some vehicles that are VERY aerodynamic to start
> with, as well as some that are less aerodynamic to
> start with.

I meant the certain vehicles which are relatively unaffected
by bike racks are liable to be pretty poor aerodynamics wise
anyway. Fitting a bike rack to a Ford Explorer or similar is
going to have a rather less dramatic impact than on
something very aerodynamic like a Honda Insight, Opel /
Vauxhall Calibra etc. You're a pedantic swine.

 

[P E T E F A G E]

On Wed, 17 Mar 2004 21:10:39 -0000, "Doki" <[email protected]>
wrote:

>
>
>P e t e F a g e r l i n wrote:

>>>> My comments relate to driving at high speeds where the
>>>> additional wind resistance doesn't make that great a
>>>> difference, for some vehicles, based upon my
>>>> experience.
>>>
>>> Some vehicles = ones that aren't particularly
>>> aerodynamic to start with?
>>
>> Nope. Some vehicles that are VERY aerodynamic to start
>> with, as well as some that are less aerodynamic to
>> start with.
>
>I meant the certain vehicles which are relatively
>unaffected by bike racks are liable to be pretty poor
>aerodynamics wise anyway.

Not in my experience.

> Fitting a bike rack to a Ford Explorer or similar is going
> to have a rather less dramatic impact than on something
> very aerodynamic like a Honda Insight, Opel / Vauxhall
> Calibra etc. You're a pedantic swine.

You're a clueless tool then. Please read your initial
sweeping generalization about aerodynamic impacts being
"very bad."

Don't assume that I'm only referring to vehicles with poor
aerodynamics when I relate my experiences and you'll maybe
look like less of an idiot.

As noted before, it depends upon the vehicles and the
speeds. At high speeds, the effect upon the aerodynamics is
hardly "very bad," in my experience, in my vehicles.

 

[P E T E F A G E]

"Doki" <[email protected]> wrote in message
news:[email protected]...
>
>
> P e t e F a g e r l i n wrote:
> > On Wed, 17 Mar 2004 21:10:39 -0000, "Doki"
> > <[email protected]> wrote:
> >
> >>
> >>
> >> P e t e F a g e r l i n wrote:
> >
> >>>>> My comments relate to driving at high speeds where
> >>>>> the additional wind resistance doesn't make that
> >>>>> great a difference, for some vehicles, based upon my
> >>>>> experience.
> >>>>
> >>>> Some vehicles = ones that aren't particularly
> >>>> aerodynamic to start with?
> >>>
> >>> Nope. Some vehicles that are VERY aerodynamic to start
> >>> with, as well as some that are less aerodynamic to
> >>> start with.
> >>
> >> I meant the certain vehicles which are relatively
> >> unaffected by bike racks are liable to be pretty poor
> >> aerodynamics wise anyway.
> >
> > Not in my experience.
> >
> >> Fitting a bike rack to a Ford Explorer or similar is
> >> going to have a rather less dramatic impact than on
> >> something very aerodynamic like a Honda Insight, Opel /
> >> Vauxhall Calibra etc. You're a pedantic swine.
> >
> > You're a clueless tool then. Please read your initial
> > sweeping generalization about aerodynamic impacts being
> > "very bad."
>
> I've already clarified what I meant by "very bad" in this
> thread. It
seems
> reasonable enough to me that if you fit a bike rack to
> the top of
something
> big with poor aerodymamics, it's going to have less impact
> than fitting it to something small with good aerodynamics.

You seem to be changing your tune a bit. Now it's "something
small with good aerodynamics." That's interesting. Why are
you discounting vehicles that aren't small yet have good
aerodynamics.

> > Don't assume that I'm only referring to vehicles with
> > poor aerodynamics when I relate my experiences and
> > you'll maybe look like less of an idiot.
>
> I didn't assume, I asked a question. Perhaps you'd look
> less of an idiot
if
> you read my post correctly.

You asked a question, and then made a statement using
vehicles that you consider to be "very aerodynamic." Read
your pap again if you're still confused.

> > As noted before, it depends upon the vehicles and the
> > speeds. At high speeds, the effect upon the aerodynamics
> > is hardly "very bad," in my experience, in my vehicles.
>
> At high speeds the effect of bikes strapped to your roof
> isn't very bad?

No, it's not.

> Normally drag quadruples when speed doubles, so you'd
> expect the impact
from
> having a bike on top of your car to get worse as speeds
> increase.

Of course it gets worse. Is it "very bad"? Nope. My mileage
changes by only a few mpg at high speeds vs. not using a
rack, on the routes that I drive.

 

[Chris Phillipo]

In article <[email protected]>,
[email protected] says...
> On Sat, 13 Mar 2004 21:27:40 -0000, "Doki"
> <[email protected]> wrote:
>
> >Why not just take the wheels off and chuck the bikes in
> >the boot (trunk)? Bike racks do very bad things to your
> >cars aerodynamics,
>
> That is really dependent upon the aerodynamics of the
> vehicle.
>
> Roof racks don't have to have that great an impact, let
> alone do "very bad things" to a vehicle's aerodynamics.
>
>
>

I think you are spoiled by Mercedes and Porche horsepower
Pete. On a base model Civic hatchback with a roof rack
fitted, you are constantly checking your rear view mirror to
see if someone has attached a larget kite to your bumper.
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia http://www.ramsays-
online.com

 

[Chris Phillipo]

> > I just filled up. It was like $1.88 for premium gas. If
> > I'd gone for the regular gas it would've been more like
> > $1.60, I think.

It's always above $2.50 in Canada and it's the same damn
gas!
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia http://www.ramsays-
online.com

 

[Adam]

"Doki" <[email protected]> wrote in message news:<[email protected]>...
> P e t e F a g e r l i n wrote:
> > On Wed, 17 Mar 2004 21:10:39 -0000, "Doki"
> > <[email protected]> wrote:
> >> P e t e F a g e r l i n wrote:
>
> >>>>> My comments relate to driving at high speeds where
> >>>>> the additional wind resistance doesn't make that
> >>>>> great a difference, for some vehicles, based upon my
> >>>>> experience.
> >>>>
> >>>> Some vehicles = ones that aren't particularly
> >>>> aerodynamic to start with?
> >>>
> >>> Nope. Some vehicles that are VERY aerodynamic to start
> >>> with, as well as some that are less aerodynamic to
> >>> start with.
> >>
> >> I meant the certain vehicles which are relatively
> >> unaffected by bike racks are liable to be pretty poor
> >> aerodynamics wise anyway.
> >
> > Not in my experience.
> >
> >> Fitting a bike rack to a Ford Explorer or similar is
> >> going to have a rather less dramatic impact than on
> >> something very aerodynamic like a Honda Insight, Opel /
> >> Vauxhall Calibra etc. You're a pedantic swine.
> >
> > You're a clueless tool then. Please read your initial
> > sweeping generalization about aerodynamic impacts being
> > "very bad."
>
> I've already clarified what I meant by "very bad" in this
> thread. It seems reasonable enough to me that if you fit a
> bike rack to the top of something big with poor
> aerodymamics, it's going to have less impact than fitting
> it to something small with good aerodynamics.

AIUI, the biggest factor in aerodynamic (or any fluid for
that matter) drag is frontal area in the axis of travel (of
the air, rather than the car). The next biggest is the ratio
of area to length (the more laminar the flow, the less the
pressure 'hole' behind the object will be).

Bikes (plus racks) represent a pretty small percentage of
the frontal area of the bike/car combination. Firther,
they're pretty long compared to their frontal area. Some
quick calculations give me a figure (of two bikes plus rack
as a percentage of total frontal area) of around 10% - and
that's based on my mini [and it's being generous with the
bike dimensions and stingy with the mini dimensions]. That
doesn't strike me as very bad.

-8<- snip ->8-

> > As noted before, it depends upon the vehicles and the
> > speeds. At high speeds, the effect upon the aerodynamics
> > is hardly "very bad," in my experience, in my vehicles.
>
> At high speeds the effect of bikes strapped to your roof
> isn't very bad? Normally drag quadruples when speed
> doubles, so you'd expect the impact from having a bike on
> top of your car to get worse as speeds increase. That
> said, bikes may be more aerodynamic at some speeds than
> others. But I'm not an aerodynamicist.

Drag doesn't exactly quadruple as speed doubles, but is is a
*very* approximate squared rule (hence the front facing area
being the dominant factor). However, at any speed the ratio
of frontal areas will remain the same , and the total
percentage of drag represented by the bikes will remain the
same. What will increase the percentage drag of the bikes
more considerably would be a side-wind.

Further, at (any) speed a car will push a shock wave in
front of it; the faster the vehicle, the larger and further
forward the shock wave. This will change the surface
aerodynamics and I would have thought would go some way to
reducing the drag of the racks, if not the bikes
- in effect the racks get partly drafted by the leading
surface of either the roof/windscreen or the bonnet (hood)
depending on how fast the vehicle is and its shape. With
more aerodynamic cars, this effect will be less, as the
air flow over the bonnet (hood), windscreen and roof would
be more laminar (without the racks in place).

Sorry, couldn't resist adding my tuppence-worth...

Adam...

 

[Monique Y. Herm]

On 2004-03-18, Adam penned:
>
> Further, at (any) speed a car will push a shock wave
> in front of it; the faster the vehicle, the larger
> and further forward the shock wave. This will change
> the surface aerodynamics and I would have thought
> would go some way to reducing the drag of the racks,
> if not the bikes
> - in effect the racks get partly drafted by the leading
> surface of either the roof/windscreen or the bonnet
> (hood) depending on how fast the vehicle is and its
> shape. With more aerodynamic cars, this effect will be
> less, as the air flow over the bonnet (hood), windscreen
> and roof would be more laminar (without the racks in
> place).
>

So you're saying that the less aerodynamic the car, the less
the bikes will impact mpg?

--
monique