Distribution of frame sizes?

Bob Wheeler wrote:
wrote:
Bob Wheeler wrote:

Qui si parla Campagnolo wrote:

wrote:


Hi Everyone,

Perhaps someone who runs a bike store or has other relevant experience
can help me out here.

Someone I know who owns a health club is contemplating buying a fleet
of bikes to rent/loan to spinning folks for organized rides. I am
tentatively in charge of getting the bikes.

So my question is, which percentage of the fleet should each size be?
The bikes I'm looking at come in 2cm increments (c-c): 60, 58, 56, 54,
52, 50, 48. For various reasons we are not going with S, M, L compact
style frames.

So for a fleet of 50 bikes, how many of each size?? What is the bike
size curve for the population of road riders?

Thanks!



Well of course, most men ride around a 56cm-58cm or so, most women
52-50cm or so..most should be there. A couple largest an smallest, most
in the moiddle, of course.

20-56cm
10-52cm
5-58
3-60
5-50
3-48
6-54


or something like that. 54s for shortish men, tallish women.


Joseph


The statistics on leg length give a mean of 96cm for a male 20yr or
older. The SD is about 4.5cm. This isn't stand over height but the sum
of knee height and upper leg length. If you scale this to an average
male frame of 57cm, then the SD becomes about 1.7cm.

These measurements follow a normal distribution, so for men you will
need about 12% 60cm, 38% 58cm, 38% 56cm, 10% 54cm, and 2% 52cm.
Assuming an average of 53cm for women, you will need about 2% 58cm, 10%
56cm, 38% 54cm, 38% 52cm, 10% 51cm and 2% 50cm.

Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

The problem, of course, is what is the ratio of men to women. Guess
wrong and you will have mud on your face.

--
Bob Wheeler --- http://www.bobwheeler.com/
ECHIP, Inc. --- Randomness comes in bunches.


Sounds good to me, but what stand-over do you suppose this 96cm
corresponds to? If I knew that I could apply our standard sizing
formula. How did you arrive at 57cm?

This is quite interesting. Where did you get the statistical info on
leg length? I have been curious for a while about this topic. In
figuring out things about my seating position, I have come across
statements like "If you have long thighs, you should do foo, otherwise
do bar." How do I know if I have long thighs? Sounds like your source
may be the answer!

Joseph


I got it from
http://www.cdc.gov/nchs/about/major/...20Measures.htm



--
Bob Wheeler --- http://www.bobwheeler.com/
ECHIP, Inc. --- Randomness comes in bunches.

Lots of interesting info there. The problem is matching a frame size to
a composite leg length that is measured in some unknown way. Maybe
using height would be just as good. I assume the correlation for inseam
related to total height is pretty close. Close enough that we could
just say that inseam is a straight ratio to height. (I am obviously not
a statistician, but you see what I mean, right?)

So what sample size do we need measurments on to make a reasonable
guess as to what a "normal" inseam to height ratio is if we are
interested in a precision of about 1cm? Maybe enough folks on this NG
will supply data. And then this ratio could be applied to the data on
heights to get an inseam curve.

Or do you have some other suggestion?

Thanks!

Joseph

writes:

Hi Everyone,

So my question is, which percentage of the fleet should each size be?
The bikes I'm looking at come in 2cm increments (c-c): 60, 58, 56, 54,
52, 50, 48. For various reasons we are not going with S, M, L compact
style frames.

Assuming that most people buy roughly the correct size of bike, and
assuming that women & men sell used bikes at roughly the same rate,
the distribution of used bikes being sold should roughly match the
distribution of new bikes being bought. Therefore, all the
information that you need is contained at the histogram (for road
bikes, both sexes) at this URL location :

http://sporting-goods.search.ebay.co...1QQsacatZ98084

I'll just quote the histogram (on the left side of the screen, about
1/4 of the way down the page) that is currently being reported :

Frame Size
44-45 cm (7)
46-47 cm (28)
48-49 cm (44)
50-51 cm (79)
52-53 cm (99)
54-55 cm (146)
56-57 cm (135)
58-59 cm (115)
60-61 cm (63)
62-63 cm (24)
64-65 cm (11)
XS (7)
S (53)
M (234)
L (245)
XL (31)
Other (62)


- Don Gillies
San Diego, CA

Why not just survey the spin class participants?

There's also no inherent tradeoff between compact geometry and fit.
Assuming a decent number of sizes to choose from, (i.e. more than just
S,M,L) you can fit people just as well, and new riders might feel more
comfortable with more standover.

Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

Something went wrong with at least the women's numbers; we sell a very large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example. And
keep in mind that you can't assume similar styles of bikes will fit both men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to do.

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


"Bob Wheeler" wrote in message
...
Qui si parla Campagnolo wrote:
wrote:

Hi Everyone,

Perhaps someone who runs a bike store or has other relevant experience
can help me out here.

Someone I know who owns a health club is contemplating buying a fleet
of bikes to rent/loan to spinning folks for organized rides. I am
tentatively in charge of getting the bikes.

So my question is, which percentage of the fleet should each size be?
The bikes I'm looking at come in 2cm increments (c-c): 60, 58, 56, 54,
52, 50, 48. For various reasons we are not going with S, M, L compact
style frames.

So for a fleet of 50 bikes, how many of each size?? What is the bike
size curve for the population of road riders?

Thanks!



Well of course, most men ride around a 56cm-58cm or so, most women
52-50cm or so..most should be there. A couple largest an smallest, most
in the moiddle, of course.

20-56cm
10-52cm
5-58
3-60
5-50
3-48
6-54


or something like that. 54s for shortish men, tallish women.
Joseph



The statistics on leg length give a mean of 96cm for a male 20yr or older.
The SD is about 4.5cm. This isn't stand over height but the sum of knee
height and upper leg length. If you scale this to an average male frame of
57cm, then the SD becomes about 1.7cm.

These measurements follow a normal distribution, so for men you will need
about 12% 60cm, 38% 58cm, 38% 56cm, 10% 54cm, and 2% 52cm. Assuming an
average of 53cm for women, you will need about 2% 58cm, 10% 56cm, 38%
54cm, 38% 52cm, 10% 51cm and 2% 50cm.

Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

The problem, of course, is what is the ratio of men to women. Guess wrong
and you will have mud on your face.

--
Bob Wheeler --- http://www.bobwheeler.com/
ECHIP, Inc. --- Randomness comes in bunches.

Dave wrote:
Why not just survey the spin class participants?

There's also no inherent tradeoff between compact geometry and fit.
Assuming a decent number of sizes to choose from, (i.e. more than just
S,M,L) you can fit people just as well, and new riders might feel more
comfortable with more standover.

This may be true, but the choice of bikes also has a lot to do with
"marketing" future sales, and other sponsorship deals, etc.

The club has a tie-in with a shop that focuses on a particular brand,
as well as sposors a team which uses this brand. And part of their
pitch is "other clubs force everyone onto S, M, L bikes, while we take
the time to find a bike that fits, blah, blah, blah"

Joseph

Mike Jacoubowsky wrote:
Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

Something went wrong with at least the women's numbers; we sell a very large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example. And
keep in mind that you can't assume similar styles of bikes will fit both men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to do.


Having an appropriate number of WSD bikes is important. Just a thought,
but perhaps you sell a large number of these WSD bikes because you are
known to carry them and known to give good service to women who need
them?

We do have some info on the club members but this project will include
many more folks than just the folks in the club. Spouses, etc, as well
as members of clubs in the same franchise but owned by others. In is
not practical to get accurate info that way.

Assuming I can get enough info on the heights of the folks involved,
what do you suppose is a good height:inseam ratio to guess male inseam
from known height? Female? I've been using .48 for males which is based
on a slightly modified version of myself.

Joseph

Donald Gillies wrote:
writes:

Hi Everyone,

So my question is, which percentage of the fleet should each size be?
The bikes I'm looking at come in 2cm increments (c-c): 60, 58, 56, 54,
52, 50, 48. For various reasons we are not going with S, M, L compact
style frames.

Assuming that most people buy roughly the correct size of bike, and
assuming that women & men sell used bikes at roughly the same rate,
the distribution of used bikes being sold should roughly match the
distribution of new bikes being bought. Therefore, all the
information that you need is contained at the histogram (for road
bikes, both sexes) at this URL location :

http://sporting-goods.search.ebay.co...1QQsacatZ98084

I'll just quote the histogram (on the left side of the screen, about
1/4 of the way down the page) that is currently being reported :

Frame Size
44-45 cm (7)
46-47 cm (28)
48-49 cm (44)
50-51 cm (79)
52-53 cm (99)
54-55 cm (146)
56-57 cm (135)
58-59 cm (115)
60-61 cm (63)
62-63 cm (24)
64-65 cm (11)
XS (7)
S (53)
M (234)
L (245)
XL (31)
Other (62)


- Don Gillies
San Diego, CA

That is very interesting. It is fun seeing all the info people are
finding. This may be the most useful batch of info so far.

But here is a theory: The upper and lower ends may be exagerated. Since
the extreme ends of the curve will always have a smaller pool of local
buyers, perhaps folks with really small bikes or really big bikes will
be more likely to try to sell on ebay to reach a larger market.
Likewise with buyers.

I live in the boonies and there are about 30 active members of my
bicycle club. If I had some 56cm fames to sell, I'm sure I could sell
them to one of them no problem. But I have a 59 for sale, and there is
only one other guy who rides a 59, and he doesn't want it. So I'll try
ebay.

Just a theory, but the info looks good.

Thanks!

Joseph

Wrote:
Dave wrote:
Why not just survey the spin class participants?

There's also no inherent tradeoff between compact geometry and fit.
Assuming a decent number of sizes to choose from, (i.e. more than
just
S,M,L) you can fit people just as well, and new riders might feel
more
comfortable with more standover.

This may be true, but the choice of bikes also has a lot to do with
"marketing" future sales, and other sponsorship deals, etc.

The club has a tie-in with a shop that focuses on a particular brand,
as well as sposors a team which uses this brand. And part of their
pitch is "other clubs force everyone onto S, M, L bikes, while we take
the time to find a bike that fits, blah, blah, blah"

Joseph

If the marketting emphasis is on bicycle "fit", rather than merely go
with a wide variety of standard proportion frames, you might also want
to consider some other combinations such as 54 long top tube for
persons with short legs & long arms, or a 62 short top tube for persons
with short arms/long legs. For many persons with the long arm/short
leg senario the compact geometry makes more sense than standard
frames-does the manufacture make some compact bike frames?

The issue hasn't been discussed, but will there be still growing youths
in the mix that might also skew the sizing distribution downward?


--
meb

Something went wrong with at least the women's numbers; we sell a very
large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example.
And
keep in mind that you can't assume similar styles of bikes will fit both
men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health
club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to
do.


Having an appropriate number of WSD bikes is important. Just a thought,
but perhaps you sell a large number of these WSD bikes because you are
known to carry them and known to give good service to women who need
them?

That's part of it, sure, but keep in mind that, what you're doing may bring
out more women wanting to participate than men. Women often gravitate
towards things that are perceived as "safe" ways to exercise, and riding in
groups is seen as safer than riding on their own... plus cycling can be a
very social activity, more so than, say, running). This may be a way to get
a lot more women interested in joining the club.

We do have some info on the club members but this project will include
many more folks than just the folks in the club. Spouses, etc, as well
as members of clubs in the same franchise but owned by others. In is
not practical to get accurate info that way.

However, if your club is large enough (and given the number of bikes you're
talking about, it sounds like it is), you still may get a fairly
representative sampling by checking out the needs of your current
membership. At the very least this should serve as a safety check for any
numbers you might derive from formulas.

Assuming I can get enough info on the heights of the folks involved,
what do you suppose is a good height:inseam ratio to guess male inseam
from known height? Female? I've been using .48 for males which is based
on a slightly modified version of myself.

Y'know, having been in business for 25+ years, and having always seen proper
fit as a big thing, you'd think I would have kept track of something as
simple as "Customers of "x" height, on average, have purchased bikes of "y"
size. But we haven't. We have fit charts that we use (New England Cycling
Academy) and don't pay much attention to the connection between height and
frame size. Having said that, 9 times out of 10 I can look at someone and
come up with what frame size they're going to take, when they're standing
(not when on a bike). I can even guess pretty well where the stem's going to
be too, just by noting how much of the person are legs vs arms vs torso.

But getting back to your dilemma- have you thought about calling up a bike
rental company, perhaps a travel company, and see how their size runs skew?

Keep in mind that, no matter how hard you try, you'll get it wrong. What
that means to me is that it makes sense to leave a fair amount of room to
fine-tune things down the road, so don't buy more than, say, 60% initially.
Start your program a bit slower than you might have been thinking of doing,
and any errors will be far less costly (because you can correct them with
as-yet-unpurchased inventory).

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


wrote in message
ups.com...

Mike Jacoubowsky wrote:
Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

Something went wrong with at least the women's numbers; we sell a very
large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example.
And
keep in mind that you can't assume similar styles of bikes will fit both
men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health
club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to
do.


Having an appropriate number of WSD bikes is important. Just a thought,
but perhaps you sell a large number of these WSD bikes because you are
known to carry them and known to give good service to women who need
them?

We do have some info on the club members but this project will include
many more folks than just the folks in the club. Spouses, etc, as well
as members of clubs in the same franchise but owned by others. In is
not practical to get accurate info that way.

Assuming I can get enough info on the heights of the folks involved,
what do you suppose is a good height:inseam ratio to guess male inseam
from known height? Female? I've been using .48 for males which is based
on a slightly modified version of myself.

Joseph

Mike Jacoubowsky wrote:
Something went wrong with at least the women's numbers; we sell a very
large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example.
And
keep in mind that you can't assume similar styles of bikes will fit both
men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health
club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to
do.


Having an appropriate number of WSD bikes is important. Just a thought,
but perhaps you sell a large number of these WSD bikes because you are
known to carry them and known to give good service to women who need
them?

That's part of it, sure, but keep in mind that, what you're doing may bring
out more women wanting to participate than men. Women often gravitate
towards things that are perceived as "safe" ways to exercise, and riding in
groups is seen as safer than riding on their own... plus cycling can be a
very social activity, more so than, say, running). This may be a way to get
a lot more women interested in joining the club.


Getting folks out on the road who might not feel comfortable doing it
on their own, oor who might not know where to start, or just need akick
in the pants is what this is all about. I, as well as all others
involved think we will get a large turn out of women as well.





We do have some info on the club members but this project will include
many more folks than just the folks in the club. Spouses, etc, as well
as members of clubs in the same franchise but owned by others. In is
not practical to get accurate info that way.

However, if your club is large enough (and given the number of bikes you're
talking about, it sounds like it is), you still may get a fairly
representative sampling by checking out the needs of your current
membership. At the very least this should serve as a safety check for any
numbers you might derive from formulas.


I'll try to get some actual nubers, but it's a whole turf-war thing
with nagging certain uncooperatvie people that is a can of worms I
don't want to open.



Assuming I can get enough info on the heights of the folks involved,
what do you suppose is a good height:inseam ratio to guess male inseam
from known height? Female? I've been using .48 for males which is based
on a slightly modified version of myself.

Y'know, having been in business for 25+ years, and having always seen proper
fit as a big thing, you'd think I would have kept track of something as
simple as "Customers of "x" height, on average, have purchased bikes of "y"
size. But we haven't. We have fit charts that we use (New England Cycling
Academy) and don't pay much attention to the connection between height and
frame size. Having said that, 9 times out of 10 I can look at someone and
come up with what frame size they're going to take, when they're standing
(not when on a bike). I can even guess pretty well where the stem's going to
be too, just by noting how much of the person are legs vs arms vs torso.

But getting back to your dilemma- have you thought about calling up a bike
rental company, perhaps a travel company, and see how their size runs skew?


The only folks I have to call are the competition! For sales number I
have the distributors, but they don't know the breakdown by sex, and
may have ulterior motives in any number they report.



Keep in mind that, no matter how hard you try, you'll get it wrong. What
that means to me is that it makes sense to leave a fair amount of room to
fine-tune things down the road, so don't buy more than, say, 60% initially.
Start your program a bit slower than you might have been thinking of doing,
and any errors will be far less costly (because you can correct them with
as-yet-unpurchased inventory).

That's why we are only getting 50 to start!

Thanks for the input!

Joseph


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


wrote in message
ups.com...

Mike Jacoubowsky wrote:
Assuming half men and half women renters, you will need
3 60cm,
10 58cm,
12 56cm,
12 54cm,
10 52cm
3 50cm or 2 50cm and 1 48cm

Something went wrong with at least the women's numbers; we sell a very
large
qty of 47cm & 51cm Trek WSD (Women Specific Design) models, for example.
And
keep in mind that you can't assume similar styles of bikes will fit both
men
& women equally; a large number of women definitely fit WSD-style bikes
(typically with shorter top tubes) better.

I'm not sure why you need to guess at this; your client owns a health
club
for goodness sake, what's so tough about doing a survey of their heights?
Seems like profiling height, weight & sex would be a standard thing to
do.


Having an appropriate number of WSD bikes is important. Just a thought,
but perhaps you sell a large number of these WSD bikes because you are
known to carry them and known to give good service to women who need
them?

We do have some info on the club members but this project will include
many more folks than just the folks in the club. Spouses, etc, as well
as members of clubs in the same franchise but owned by others. In is
not practical to get accurate info that way.

Assuming I can get enough info on the heights of the folks involved,
what do you suppose is a good height:inseam ratio to guess male inseam
from known height? Female? I've been using .48 for males which is based
on a slightly modified version of myself.

Joseph