Fit kit experience

I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and femur
lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply measured my
crotch to foot and hand to shoulder blade distances. The end result put me on a bike that felt
extremely cramped. Is it normal for the fit kit to ignore the limb length variances between the knee
cap and elbow?

 

> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
> measured my crotch to foot and hand to shoulder blade distances. The end result put me on a
> bike that
felt
> extremely cramped. Is it normal for the fit kit to ignore the limb length variances between the
> knee cap and elbow?

What's wrong is to take the fit measurements and not verify their applicability to the particular
cyclist. The FitKit is a great place to start, and gets the majority of people very close to where
they need to be, sometimes spot on. But not everybody. The person taking the measurements should be
watching the person ride, checking out their back (straight or arched... arched can be a symptom of
many issues that need to be addressed), making sure their arms aren't locked, etc. Flexibility
varies from person to person; you might be able to ride a bit lower than the average person, and
thus possibly the cramped feeling.

Femur length can be mesured using the FitKit, but most often isn't an issue if someone's also doing
a plumb line for knee-over-pedal.

But really, like any measurement, it's a starting point. Anybody who tells you they can fit you
perfectly with measurements alone, particularly static ones, isn't doing a great job. Having said
that, they're still doing more for their customers than 90% of the shops out there. I'm going to
break something the next time I hear someone come in saying that they've been told they have to have
their nose in a particular place over the front axle.

--Mike-- Chain Reaction Bicycles www.ChainReaction.com

"BillX" <[email protected]> wrote in message news:[email protected]...
> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
> measured my crotch to foot and hand to shoulder blade distances. The end result put me on a
> bike that
felt
> extremely cramped. Is it normal for the fit kit to ignore the limb length variances between the
> knee cap and elbow?

 

I've come to learn over years of messing with bike fit that I'm rather long in the torso relative to
my legs. When I bought a rather high-end frame from an allegedly high-end shop a few years back,
they charged me $45 for a fit kit which they allegedly refunded in the price of the bike they sold
me. As the years have gone by and I've learned more about bike fit, I've learned what a disservice
that bike shop did. While I was fine on the frame from a saddle height and standover standpoint (how
many of us rack ourselves on our top tubes?). I was cramped because the top tube was too short. So
they kept putting me on longer and longer stems. This story could go on and on. To make it short, I
finally learned what I needed on my own and assembled a bike that now fits me like a glove. I can
ride 100 miles and it's just as comfortable as if I had only done 20. But I've really studied the
stuff. I think as Mike Jacoubowsky said, the fit kit is a good starting point if you happen to have
it done at one of the 10% of those shops that know how to really use it and what else needs to be
taken into account.

This is just an aside, but it just came to mind. I've never had a fit kit or a bike shop person or
anyone ever mention handlebar width to me. One day I was on a friend's bike. He's the same height as
me. His bars were much wider than mine and I couldn't believe how much more comfortable they were.
So I started researching handlebar width and discovered I needed to make a drastic change. When I
did, I couldn't believe the dramatic difference it made in my comfort on the bike ... and my power
in out-of-saddle efforts, etc. I hardly ever see or hear anyone talk about bar width ... but it can
be a very significant thing.

FWIW, Bob C. "BillX" <[email protected]> wrote in message
news:[email protected]...
> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
> measured my crotch to foot and hand to shoulder blade distances. The end result put me on a
> bike that
felt
> extremely cramped. Is it normal for the fit kit to ignore the limb length variances between the
> knee cap and elbow?

 

> This is just an aside, but it just came to mind. I've never had a fit kit or a bike shop person or
> anyone ever mention handlebar width to me. One
day
> I was on a friend's bike. He's the same height as me. His bars were much wider than mine and I
> couldn't believe how much more comfortable they
were.
> So I started researching handlebar width and discovered I needed to make a drastic change. When I
> did, I couldn't believe the dramatic difference it made in my comfort on the bike ... and my power
> in out-of-saddle efforts, etc. I hardly ever see or hear anyone talk about bar width ... but it
> can be a very significant thing.

The FitKit measurements do include shoulder width, for help in determining appropriate handlebar
width. Perhaps some shops ignore it? That's unfortunate since bar width can make quite a difference
in comfort and out-of-the-saddle climbing. Back in the day there wasn't much choice; nearly all bars
were Cinelli 64s, with a 40cm width. But over time we've found that wider bars are definitely an
advantage for bigger folk, and I could never go back to narrow bars now that I'm "spoiled" by 44cm
width (and I don't even have shoulders... more like ski slopes!).

It's almost painful for me to see some guy come in with an older bike, big broad shoulders and a
39cm wide bar. I guess if you don't know any better, it's not that big a deal, but once you get
someone on appropriate-width bars, they're blown away by the difference.

While we're on handlebars, another issue that comes up at times are bars with too much forward
reach. Since STI came along, bars like that don't make a lot of sense. They were designed with the
idea that you wanted an aggressive position when you were out on the brake hoods, and a more relaxed
position up on top (the straight part of the bar). Trouble is, with STI, you spend a lot of time on
the lever hoods, so that really needs to be comfortable position for long periods of time. If you
shorten the stem to accomplish that, then the top part is way too close. The solution is to shorten
up the reach, so you have more useable hand positions, without sacrificing comfort. If you want to
get aggressive, go for the drops.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

 

"Mike Jacoubowsky" <[email protected]> wrote in message
news:LZ%[email protected]s.prodigy.com...
> > This is just an aside, but it just came to mind. I've never had a fit
kit
> > or a bike shop person or anyone ever mention handlebar width to me. One
> day
> > I was on a friend's bike. He's the same height as me. His bars were
much
> > wider than mine and I couldn't believe how much more comfortable they
> were.
> > So I started researching handlebar width and discovered I needed to make
a
> > drastic change. When I did, I couldn't believe the dramatic difference
it
> > made in my comfort on the bike ... and my power in out-of-saddle
efforts,
> > etc. I hardly ever see or hear anyone talk about bar width ... but it
can
> > be a very significant thing.
>
> The FitKit measurements do include shoulder width, for help in determining appropriate handlebar
> width. Perhaps some shops ignore it? That's unfortunate since bar width can make quite a
> difference in comfort and out-of-the-saddle climbing. Back in the day there wasn't much choice;
> nearly all bars were Cinelli 64s, with a 40cm width. But over time we've found that wider bars are
> definitely an advantage for bigger folk, and I could never go back to narrow bars now that I'm
> "spoiled" by 44cm width
(and
> I don't even have shoulders... more like ski slopes!).
>
> It's almost painful for me to see some guy come in with an older bike, big broad shoulders and a
> 39cm wide bar. I guess if you don't know any
better,
> it's not that big a deal, but once you get someone on appropriate-width bars, they're blown away
> by the difference.
>
> While we're on handlebars, another issue that comes up at times are bars with too much forward
> reach. Since STI came along, bars like that don't make a lot of sense. They were designed with the
> idea that you wanted an aggressive position when you were out on the brake hoods, and a more
relaxed
> position up on top (the straight part of the bar). Trouble is, with STI, you spend a lot of time
> on the lever hoods, so that really needs to be comfortable position for long periods of time. If
> you shorten the stem to accomplish that, then the top part is way too close. The solution is to
> shorten up the reach, so you have more useable hand positions, without sacrificing comfort. If you
> want to get aggressive, go for the drops.
>
> --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
>
I have a few pair of Ritchey Pro bars that have an "extra" 5mm of reach built in. Makes up for my TT
being 5mm too short...

Mike

 

BillX-<< I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia
and femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
measured my crotch to foot and hand to shoulder blade distances.

Then it was a poor fit, IMO.(It's called a humerous-sp?)...Femur length is essential, inseam is
meaningless w/o this measurement as it determines seat tube ANGLE.

<< Is it normal for the fit kit to ignore the limb length variances between the knee cap and elbow?

Maybe 'fit kit', but a good anatomic fit does not ignore these measurements.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

I recently had a custom Litespeed frame designed. FWIW, the Litespeed custom frame designer
mentioned that the fit kit tends to specify a top tube length that's too short. Having said that,
the fit kit suggested a top tube length for me that was correct.

I liked the method my LBS used to apply the fit kit. They first measured crotch height, shoulder
width and torso height (maybe some other things), but not smaller measurements on arms or legs. They
then did a "sanity check" of the fit kit's measurements against my current bike and a stock
Litespeed I test rode, and adjusted those measurements based on those bikes, my riding style and the
goals of the new bike.

"BillX" <[email protected]> wrote in message news:<[email protected]>...
> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
> measured my crotch to foot and hand to shoulder blade distances. The end result put me on a bike
> that felt extremely cramped. Is it normal for the fit kit to ignore the limb length variances
> between the knee cap and elbow?

 

On Wed, 07 May 2003 01:34:04 GMT, "Mike Jacoubowsky/Chain Reaction Bicycles"
<[email protected]> wrote:

>But really, like any measurement, it's a starting point. Anybody who tells you they can fit you
>perfectly with measurements alone, particularly static ones, isn't doing a great job. Having said
>that, they're still doing more for their customers than 90% of the shops out there. I'm going to
>break something the next time I hear someone come in saying that they've been told they have to
>have their nose in a particular place over the front axle.
>

I posted this here over four years ago and just found it via google. I've verified some of the links
are still valid.

"While I see you've received a number of other responses, my best advice would be to read
http://www.sheldonbrown.com/frame_sizing.html. Then follow the links at the bottom of the page. By
the time you're finished you'll know more about bike fit than 95% of LBS employees."

jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

 

Heck, a number of years ago, Gary Klein wrote an article about fitting people using nothing but
*height*. Don't believe that ANY given fitting system is going to provide a 100% solution. What most
do is give you a good starting point. A fitter with lots of experience with different types of
riders can fine tune a position from there, but even that is not an exact science.

Consider this. Lance Armstrong worked with numerous coaches over the years to fine tune his time
trial position. It wasn't until he went into the wind tunnel with equipment for measuring power
output and heartrate did he find his best position. It turned out that if he was positioned for the
best aerodynamics, his power output was reduced. If he was positioned for best power output, his
aerodynamics suffered. If you look at his time trial position today, it is far from conventional.
His back is quite humped rather than flat. It just goes to show you.

So which bike fitter do you know with a wind tunnel and all of the appopriate measurement equipment
to do this type of fitting? That truth is, much of bike fit is subjective. I know all of my fit data
pretty well, but with each new bike I get, I take a bunch of wrenches along on the first few rides
to fine tune my position based on how it feels. It's difficult for any fitter to know just how you
feel in any given position. So, it's a two-way street. You need to communicate with your fitter, and
the two of you have to work together to get the best position.

Todd Kuzma Heron Bicycles Tullio's Big Dog Cyclery LaSalle, IL 815-223-1776
http://www.heronbicycles.com http://www.tullios.com

 

> Then it was a poor fit, IMO.(It's called a humerous-sp?)...Femur length is essential, inseam is
> meaningless w/o this measurement as it determines
seat
> tube ANGLE.

It doesn't determined seat tube angle, it determines setback of the saddle from the crank. The only
reason it's relevant to seat tube angle is that, if the saddle needs to be positioned way forward,
and your bike has a slack seat tube angle, you have just eaten into some of your top tube length
(which could be a good or bad thing, depending upon what you need). Or vice versa (if you need the
saddle way back, you've essentially lengthened the top tube over the published spec).

If I had my way, top tube lengths would be measured from a point centered over the bottom bracket.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

"Qui si parla Campagnolo" <[email protected]> wrote in message
news:[email protected]...
> BillX-<< I had a fit kit done a couple months ago and was surprised that
it
> didn't measure my tibia and femur lengths or radius and upper arm (whatever that bone is called)
> lengths. Rather it simply measured my crotch to foot and hand to shoulder blade distances.
>
> Then it was a poor fit, IMO.(It's called a humerous-sp?)...Femur length is essential, inseam is
> meaningless w/o this measurement as it determines
seat
> tube ANGLE.
>
>
> << Is it normal for the fit kit to ignore the limb length variances between the knee cap
> and elbow?
>
> Maybe 'fit kit', but a good anatomic fit does not ignore these
measurements.
>
>
> Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
> (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

> I liked the method my LBS used to apply the fit kit. They first measured crotch height, shoulder
> width and torso height (maybe some other things), but not smaller measurements on arms or legs.
> They then did a "sanity check" of the fit kit's measurements against my current bike and a stock
> Litespeed I test rode, and adjusted those measurements based on those bikes, my riding style and
> the goals of the new bike.

And if the person has done a lot of fits, that's fine. I can look at somebody standing near me and
nine times out of ten get a pretty good idea how the person's going to be sized (assuming they're
not wearing baggy clothing or a dress). That's just because I've done it so many thousands of times.
Experience fitting people will always trump "systems." Combine the two and you've got the ideal.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

 

Someone wrote:

> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
> measured my crotch to foot and hand to shoulder blade distances.

P.C. responded:

> Then it was a poor fit, IMO.(It's called a humerous-sp?)...Femur length is essential, inseam is
> meaningless w/o this measurement as it determines seat tube ANGLE.

You can certainly make that case if he was being fitted for a new frame.
The femur length is, indeed, related to the preferred seat tube angle.

If he was being fitted to an existing bike, however, this is irrelevant, since you can't change the
seat tube angle on most frames.

Femur length does enter into saddle setback, but the usual reference point for this is to look at
the vertical relationship between the knee and the forward pedal. You don't need to measure the
femur for this.

> << Is it normal for the fit kit to ignore the limb length variances between the knee cap
> and elbow?
>
> Maybe 'fit kit', but a good anatomic fit does not ignore these measurements.

I fail to see any relevant fit issue relating to the proportional length of the different bones of
the arm, though the overall arm length is very important indeed.

Sheldon "FitKit Plus Experience And An Educated Eye" Brown
+------------------------------------------------+
| According to the latest official figures, | 43% of all statistics are totally worthless. |
+------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

>FWIW, Bob C. "BillX" <[email protected]> wrote in message
>news:[email protected]...
>> I had a fit kit done a couple months ago and was surprised that it didn't measure my tibia and
>> femur lengths or radius and upper arm (whatever that bone is called) lengths. Rather it simply
>> measured my crotch to foot and hand to shoulder blade distances. The end result put me on a
>> bike that
>felt
>> extremely cramped. Is it normal for the fit kit to ignore the limb length variances between the
>> knee cap and elbow?
>>
>>
>
I have not touched a fit kit in something like twelve years, and it was an old kit when I got it...
... that being said ... the kit I'm familiar with did indeed include all of those measurements... as
well as shoulder width, the size of your hand and the size of your foot and others... after messing
with stacks of paper, each page full of tables it would recommend a range of sizes and angles for
tubes/stem/cranks et cetera...

OK it was a tight range but the shop was supposed to work with the riders riding style to
finalize things...

It was a real PITA .. We got a Serrota fit cycle as soon as I could afford it...

 

Mike Jacoubowsky wrote:

> The FitKit measurements do include shoulder width, for help in determining appropriate handlebar
> width. Perhaps some shops ignore it? That's unfortunate since bar width can make quite a
> difference in comfort and out-of-the-saddle climbing. Back in the day there wasn't much choice;
> nearly all bars were Cinelli 64s, with a 40cm width. But over time we've found that wider bars are
> definitely an advantage for bigger folk, and I could never go back to narrow bars now that I'm
> "spoiled" by 44cm width (and I don't even have shoulders... more like ski slopes!).
>
> It's almost painful for me to see some guy come in with an older bike, big broad shoulders and a
> 39cm wide bar. I guess if you don't know any better, it's not that big a deal, but once you get
> someone on appropriate-width bars, they're blown away by the difference.

Welllll, maybe. A lot depends on what you're used to. I grew up on bikes with 37-38 cm bars. In 1975
I briefly apprenticed to a frame builder (whatever happende do Bob Myers?) and while there I built a
custom frame for myself under his tutelege.

When time came to build up the completed frame, I went to the best-known fitter in the area and got
FitKitted. On his recommendation, I got 42 cm bars.

Although this frame was made to fit me, I never felt really comfortable on it.

Some years later, on a rainy afternoon, just for something to do I measured the handlebars of all of
my bikes. I discovered that the three most comfortable bikes I owned all had in common 37 cm bars!

I bought a pair of 37s for the Brown, and, for me, the improvement was dramatic!

I will grant that wider bars are better for standing pedaling, but I rarely do this when on a
multispeed bike, and I find the narrower bars more comfortable and more aero. I'm a large man, but
my sholders are of average width. Some folks talk about narrow bars constricting the breathing, but
this is only so if you ride with your elbows straight. I bend my elbows outward so my upper arms
don't compress my chest.

> While we're on handlebars, another issue that comes up at times are bars with too much forward
> reach. Since STI came along, bars like that don't make a lot of sense. They were designed with the
> idea that you wanted an aggressive position when you were out on the brake hoods, and a more
> relaxed position up on top (the straight part of the bar). Trouble is, with STI, you spend a lot
> of time on the lever hoods, so that really needs to be comfortable position for long periods of
> time. If you shorten the stem to accomplish that, then the top part is way too close. The solution
> is to shorten up the reach, so you have more useable hand positions, without sacrificing comfort.
> If you want to get aggressive, go for the drops.

That's a very cogent observation. I hadn't thought of that. I do generally go with stems at least 1
cm shorter than the FitKit default recommendation.

Sheldon "All Generalizations Are False" Brown +-----------------------------------+
| A smoking section in a | restaurant is like a peeing | section in a swimming pool |
+-----------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772
FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

Todd Kuzma at [email protected] wrote on 5/7/03 8:57 AM:
> Consider this. Lance Armstrong worked with numerous coaches over the years to fine tune his time
> trial position. It wasn't until he went into the wind tunnel with equipment for measuring power
> output and heartrate did he find his best position. It turned out that if he was positioned for
> the best aerodynamics, his power output was reduced. If he was positioned for best power output,
> his aerodynamics suffered. If you look at his time trial position today, it is far from
> conventional. His back is quite humped rather than flat. It just goes to show you.

IIRC - the hump in his back comes from a fused vertebrae, which compounded the issue of his
TT position.

 

On Wed, 07 May 2003 10:57:24 -0500, Todd Kuzma <[email protected]> wrote:

>Heck, a number of years ago, Gary Klein wrote an article about fitting people using nothing but
>*height*.

As part of his sales pitch to shops back in the early '80s, Bill Farrell (the original developer of
The Fit Kit) used to review some of the occult sizing methods and formulae in use before the Fit Kit
came along. One of them was to simply measure the circumference of your head. Of course, as with
most parlor tricks, he'd play with the resulting number as center-to-center or center-to-top to make
it appear even more accurate, but with some spectacularly wrong exceptions, it was generally at
least as good as "stand over the top tube..."

- - - - - - - - - - - - - - - http://www.businesscycles.com John Dacey Business Cycles Miami,
Florida 305-273-4440
- - - - - - - - - - - - - - - Now in our twentieth year. Our catalogue of track equipment: seventh
year online

 

Sheldon Brown wrote:

> The femur length is, indeed, related to the preferred seat tube angle.

To what do you attribute this Sheldon?

Andrew Bradley

 

I wrote:

>> The femur length is, indeed, related to the preferred seat tube angle.
>
Andrew Bradley asked:

> To what do you attribute this Sheldon?

Whether you subscribe to the "knee-over-pedal-spindle" religion or some variant, longer femurs will
mean that the saddle needs to go farther back.

Getting the saddle far enough back for a longfemurian either calls for a slack seat tube angle or a
layback seatpost (or some similar kluge.)

Many FitKitters are quite doctrinaire about the Holy Writ of KOPS.

See also: http://sheldonbrown.com/kops.html

Sheldon "Reserves The Right To Coin New Words As Needed" Brown
+----------------------------------------------------------+
| When I was in school, I cheated on my metaphysics exam: | I looked into the soul of the boy
| sitting next to me. | --Woody Allen |
+----------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

I have an older bike with 6 speed Shimano 600 and new bike with Ultegra 9 speed. The brake hoods on
the 6 speed are much lower and more aerodynamic on the handlebars so I feel really cramped riding
the hoods on my newer 9 speed.

Mike Jacoubowsky wrote in message ...
>> This is just an aside, but it just came to mind. I've never had a fit
kit
>> or a bike shop person or anyone ever mention handlebar width to me. One
>day
>> I was on a friend's bike. He's the same height as me. His bars were
much
>> wider than mine and I couldn't believe how much more comfortable they
>were.
>> So I started researching handlebar width and discovered I needed to make
a
>> drastic change. When I did, I couldn't believe the dramatic difference
it
>> made in my comfort on the bike ... and my power in out-of-saddle efforts, etc. I hardly ever see
>> or hear anyone talk about bar width ... but it
can
>> be a very significant thing.
>
>The FitKit measurements do include shoulder width, for help in determining appropriate handlebar
>width. Perhaps some shops ignore it? That's unfortunate since bar width can make quite a difference
>in comfort and out-of-the-saddle climbing. Back in the day there wasn't much choice; nearly all
>bars were Cinelli 64s, with a 40cm width. But over time we've found that wider bars are definitely
>an advantage for bigger folk, and I could never go back to narrow bars now that I'm "spoiled" by
>44cm width
(and
>I don't even have shoulders... more like ski slopes!).
>
>It's almost painful for me to see some guy come in with an older bike, big broad shoulders and a
>39cm wide bar. I guess if you don't know any better, it's not that big a deal, but once you get
>someone on appropriate-width bars, they're blown away by the difference.
>
>While we're on handlebars, another issue that comes up at times are bars with too much forward
>reach. Since STI came along, bars like that don't make a lot of sense. They were designed with the
>idea that you wanted an aggressive position when you were out on the brake hoods, and a more
relaxed
>position up on top (the straight part of the bar). Trouble is, with STI, you spend a lot of time on
>the lever hoods, so that really needs to be comfortable position for long periods of time. If you
>shorten the stem to accomplish that, then the top part is way too close. The solution is to shorten
>up the reach, so you have more useable hand positions, without sacrificing comfort. If you want to
>get aggressive, go for the drops.
>
>--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

 

Sheldon Brown wrote:
>
> >> The femur length is, indeed, related to the preferred seat tube angle.
> >
> Andrew Bradley asked:
>
> > To what do you attribute this Sheldon?
>
> Whether you subscribe to the "knee-over-pedal-spindle" religion or some variant, longer femurs
> will mean that the saddle needs to go farther back.

To what do you attribute this Sheldon? In other words do you have a view on what causes the "need"
you mention for the saddle to go back with long femurs?

There will probably be some sort of statistical trend relating preferred saddle position to femurs
since it is easy to see (at least at a relatively long crank-length) that there may be a need for
those of short femur to sit forward of "normal" due to "tuck angle" becoming the overriding factor
(though not everyone is worried about aerodynamics). But in this respect, the longfemurians aren't
constrained.

Does anybody out there know a reason why "long femurs = saddle back" for some mechanical reason that
is not to do with angles at the hip?

If you adopt a "sit as far back as your hips allow" or a "sit back until your hip angle is X
degrees" approach to bike fit then the long femured will be further back.

I think this is roughly the philosophy of the fit method described here:
http://www.billbostoncycles.com where they talk of "binding" occuring in the muscles crossing the
hip (not sure I've experienced that myself).

Andrew Bradley