Classic & Vintage - Bike sizing question

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View Full Version : Bike sizing question


snarkypup
04-13-11, 10:17 AM
So, I've confirmed that I'm taking my 8 students to Ireland this summer. We are renting bikes there. These are they:

http://www.clarebikehire.com/index.php/bikes-and-costs/

While I know how Rivendell suggests measuring to get the correct inseam for their bikes, I also realize that this might not be best way to measure (or it might be). We can't control things like TT length, but we can at least get them on bikes that are the right height. How should I have the kids measure themselves to get this right?

Thanks!


randyjawa
04-13-11, 12:13 PM
http://www.mytenspeeds.com/My_TenSpeeds_1/Bicycles_Table/Catalog_Scans/Peogeot_Owners_Manual_1986_1/Man_Scn_Peugeot_1_Done_6.jpg

snarkypup
04-13-11, 01:38 PM
Thanks, Randyjawa. Unfortunately, we can't access these bikes until we get to Ireland. I'm trying to figure out the best way to get their inseam measurements before we go. I know Rivendell uses the book-in-your-crotch-until-it-hurts method, but that gets an awfully high number. Is that the way to go, or should the kids be measuring inseam differently? I need to send the bike shop in Ireland an estimate of the number of small/medium/large bikes we'll need, so he can be sure to set them aside for us.

That's what I'm asking.


Mike Mills
04-13-11, 02:06 PM
So, I've confirmed that I'm taking my 8 students to Ireland this summer. We are renting bikes there. These are they:

http://www.clarebikehire.com/index.php/bikes-and-costs/

While I know how Rivendell suggests measuring to get the correct inseam for their bikes, I also realize that this might not be best way to measure (or it might be). We can't control things like TT length, but we can at least get them on bikes that are the right height. How should I have the kids measure themselves to get this right?

Thanks!

My experience with "kids" is that they have their own personal preferences regarding seat height and are usually uncomfortable with seat heights set to the "proper" height. I'd advise you to bring some tools and slowly raise the seat height over time (once per day?). Let them start where they are comfortable but work up to the proper height over time.

Oldpeddaller
04-13-11, 02:12 PM
My experience with "kids" is that they have their own personal preferences regarding seat height and are usually uncomfortable with seat heights set to the "proper" height. I'd advise you to bring some tools and slowly raise the seat height over time (once per day?). Let them start where they are comfortable but work up to the proper height over time.

They also have an unnerving habit of suddenly growing! (Based on experience of two sons and continually having to replace outgrown school trousers on a far too regular basis). As far as bike sizing goes, the 'book in the groin against the wall' method would seem to be simple and adequate. Even if they grow a half inch in leg length in the remaining weeks, that can be accommodated by seat post adjustment.

miamijim
04-13-11, 02:12 PM
Standard blue jean inseam plus 2". Considering your circumstances the easiest way would be to use Dave Moultons chart based on overall height.

randyjawa
04-13-11, 02:31 PM
Many of my on-line customers ask about fit (http://www.mytenspeeds.com/My_TenSpeeds_1/Site%20Contents/Bicycle_Basics/Buying_Vintage_Bicycles/Bicycle_Buying_4_RiskFactor_1_Page.htm). Remotely, the best I can do is...

Riding shoes on. Feet pedal width apart. Measure from the floor at the mid point between your feet, to the crotch, and I mean snug to the crotch, not other anatomical parts. If the bicycle's stand over height is one to two inches below that, your fit is pretty good.

http://www.mytenspeeds.com/My_TenSpeeds_1/images/Fit_1.jpg

So, you can get inseams measurements, here, and ask for the person, over there, to let you know what the stand over heights, of the bicycles, are (stand over height is the distance from the floor to the top of the top tube).

Not perfect but it seems to work so far.

snarkypup
04-13-11, 04:49 PM
Thanks, I'll have them do the book-in-the-crotch idea. We already know we'll have to adjust their saddles as we go.

The bikes are 19" and 21" for the "male" bikes, and 16" and 18" for the step-through bikes. These have hybrid geometry (see link above).

These kids are all over 16 years-old, so most won't grow much more in the next few months, though some of the boys might grow a bit. I'm assuming the 19" would fit boys up to roughly 5'8", depending on inseam, and the 21" is for the taller boys. The 16" would be for girls under 5'4" and the 18" would be for girls up to about 5'6". We don't have any exceptionally tall girls on this trip, but we do have one exceptionally small girl. She'll be pushing it on a 16" (her dad says she rides a 15" bike at home). Otherwise, I'm guessing I've got all four boys on 21" bikes, as all four of the boys are over 5'8" and some are pushing 6'. The girls I'm more concerned about, most are just between short and medium builds. But I'll get their inseams and find out.

I'm going to go home and measure my Raleigh. Not sure if it's a 19 or 21". That will give me some sense of how the girls will fit their frames, as I know my own inseam length. I think I'm on a 21" Raleigh, as my inseam is somewhat long (31") for my height: 5'5". My Panasonic is a 53cm and is on the border of too small, as I could ride a 54 with no problem, if it had a short TT. Anyway, if my Raleigh is a 21", that will give me a size comparison for my girls' inseams and bike sizes.

RobbieTunes
04-13-11, 05:54 PM
Kids need to suffer, anyway. Don't worry about the fit, make them draw straws.

After all, they're in high school, and they're going to Ireland. I'd ride standing up if I had to.

Mike Mills
04-13-11, 06:26 PM
After all, they're in high school, and they're going to Ireland. I'd ride standing up if I had to.

They must be kids from wealthy families. They are well blessed and fortunate to have snarkypup along as a chaperone. I know my family could NEVER afford to send me, or any of my siblings, to Ireland for summer vacation. The best I could do was save up a few bucks (working at the grocery store), load my bike with borrowed camping gear and ride into up-state New York for a week.

jrecoi
04-13-11, 07:09 PM
I have heard of a few bike fitting tricks that have worked out well for me. The first is one was passed along by Clevercycles. The distance from the armpit to fingertips is more or less close enough to the ideal distance from the top of the saddle to the bottom bracket.

In order to fit a bike, one puts their armpit on the saddle, and adjust the saddle height until the tips of their fingers are touching the bottom bracket axle.

The other trick (from David Moulton) I've heard works more for drop-bar bikes and might not be applicable to Dutch bikes, but what it does is that it adjusts for saddle-to-handlebar distance. The rider puts their elbow on the saddle nose, the tips of the fingers should be able to touch the handlebars.

snarkypup
04-13-11, 07:15 PM
They are mostly kids from wealthy families. I teach at a private school that costs $25,000 a year, and which gives a few, but not all, the kids scholarships. Some of the kids on these trips have parents who just shell out whatever they need, some families really scrimp and save to pay the additional funding for a summer trip on top of whatever they pay in tuition. It varies. I keep the trips ridiculously cheap, considering. Last year I took 15 kids (and my fellow chaperone) to England for ten days for $3000 each, including the $1600 airfare. This trip, which is 9 days total, is $3500, mostly in airfare. The thing is, when I say the kids are rich, folks assume they're snotty and obnoxious, but they definitely are not. Mostly the kids of techies from Microsoft. Nice, bright kids.

snarkypup
04-13-11, 07:46 PM
Kids need to suffer, anyway. Don't worry about the fit, make them draw straws.

After all, they're in high school, and they're going to Ireland. I'd ride standing up if I had to.

I'm all for them suffering, Robbie. That's why I'm an English teacher! I tell them all the time that one of the perks of my job is the ability to make them suffer and get paid for it. :)

That said, they're suffering in silence at home with 40 pages of Pride and Prejudice. I have to LISTEN to them if they suffer on this trip!

snarkypup
04-13-11, 07:47 PM
I have heard of a few bike fitting tricks that have worked out well for me. The first is one was passed along by Clevercycles. The distance from the armpit to fingertips is more or less close enough to the ideal distance from the top of the saddle to the bottom bracket.

In order to fit a bike, one puts their armpit on the saddle, and adjust the saddle height until the tips of their fingers are touching the bottom bracket axle.

The other trick (from David Moulton) I've heard works more for drop-bar bikes and might not be applicable to Dutch bikes, but what it does is that it adjusts for saddle-to-handlebar distance. The rider puts their elbow on the saddle nose, the tips of the fingers should be able to touch the handlebars.

Those are great tips to help with fit once we get there. I'll remember them! We will definitely be adjusting the saddle height/position and probably the bars once we get them out on the road.

Mike Mills
04-13-11, 08:22 PM
They are mostly kids from wealthy families. I teach at a private school that costs $25,000 a year, and which gives a few, but not all, the kids scholarships. Some of the kids on these trips have parents who just shell out whatever they need, some families really scrimp and save to pay the additional funding for a summer trip on top of whatever they pay in tuition. It varies. I keep the trips ridiculously cheap, considering. Last year I took 15 kids (and my fellow chaperone) to England for ten days for $3000 each, including the $1600 airfare. This trip, which is 9 days total, is $3500, mostly in airfare. The thing is, when I say the kids are rich, folks assume they're snotty and obnoxious, but they definitely are not. Mostly the kids of techies from Microsoft. Nice, bright kids.

I never meant to imply anything adverse about the kids based upon their relative wealth. It was 100% PURE, UNADULTERATED JEALOUSLY on my part - nothing more, nothing less. :)

I wish I had the time to go on such a trip. I used to have it when I was a kid. Nowadays, time is the most precious commodity. At my age, you can look down the road and actually see the end.

Those kids are very lucky.

snarkypup
04-13-11, 08:51 PM
I never meant to imply anything adverse about the kids based upon their relative wealth. It was 100% PURE, UNADULTERATED JEALOUSLY on my part - nothing more, nothing less. :)

I wish I had the time to go on such a trip. I used to have it when I was a kid. Nowadays, time is the most precious commodity. At my age, you can look down the road and actually see the end.

Those kids are very lucky.

I didn't get to do trips like this when I was their age, either, so I know what you mean. And I must say that, as I get both a free trip and I get paid to go (!), it's great from this end too. Though the planning is a bit of a nightmare, but I like to plan things. I also adore my colleague, and we have fantastic trip mojo, which is really important. All things together, these trips are really one of the top highlights of my year. The kids are kind and well-behaved, the places are beautiful and safe, and the adult company is great. I think I'm really the lucky one.

RobbieTunes
04-14-11, 06:01 AM
I'm all for them suffering, Robbie. That's why I'm an English teacher! I tell them all the time that one of the perks of my job is the ability to make them suffer and get paid for it. :)

That said, they're suffering in silence at home with 40 pages of Pride and Prejudice. I have to LISTEN to them if they suffer on this trip!
I forgot, you're the intrepid teacher of teens, taking trips. Suffer unto you the children.

Have fun, be safe. Think about us. Get them some decent poetry while you're there, aye?

snarkypup
04-14-11, 11:05 AM
Get them some decent poetry while you're there, aye?

A Constable Calls
by Seamus Heaney

His bicycle stood at the window-sill,
The rubber cowl of a mud-splasher
Skirting the front mudguard,
Its fat black handlegrips

Heating in sunlight, the "spud"
Of the dynamo gleaming and cocked back,
The pedal treads hanging relieved
Of the boot of the law.

His cap was upside down
On the floor, next his chair.
The line of its pressure ran like a bevel
In his slightly sweating hair.

He had unstrapped
The heavy ledger, and my father
Was making tillage returns
In acres, roods, and perches.

Arithmetic and fear.
I sat staring at the polished holster
With its buttoned flap, the braid cord
Looped into the revolver butt.

"Any other root crops?
Mangolds? Marrowstems? Anything like that?"
"No." But was there not a line
Of turnips where the seed ran out

In the potato field? I assumed
Small guilts and sat
Imagining the black hole in the barracks.
He stood up, shifted the baton-case

Further round on his belt,
Closed the domesday book,
Fitted his cap back with two hands,
And looked at me as he said goodbye.

A shadow bobbed in the window.
He was snapping the carrier spring
Over the ledger. His boot pushed off
And the bicycle ticked, ticked, ticked.

atmdad
04-14-11, 12:35 PM
Not to be snarky :), but have you asked the kids if they have bikes/ride much and what size bike they might possibly have.

snarkypup
04-14-11, 01:39 PM
I have asked them about their own bikes, but they mostly have mountain or road bikes, so that doesn't help too much with the sizing. And they are teenagers, so something they're dumb :). I want numbers, then I'll make a decision. Otherwise, it's: "I ride a 21 inch at home, but this bike feels huge!" for 7 days straight. Or more accurately: "My butt hurts! My back hurts! My butt hurts!"