Bike size for the missus

godders

I want to order a new bike for the missus but not too sure what size she will need. She's 5ft 7 so the companies webiste suggests a 52 Small or 54 Medium. When I have worked out the frame size required using the inseam (80cm) x .67 this comes out at about 54. However I have worked out her top tube length using torso + arm length (as described in Zinn's book) and this comes out as needing a top tube of about 52cm making the XSmall 50 cm frame the best fit. I understand that top tube length is the most important so will probably go for the XSmall. Is this right?

By the way it isn't a women's specific frame.

Thank you

Down the Road

Take her to a bikefitting store and get measured. She could be anything from a 50 cm to a 56 cm depending on how she is put together.

Your question is like asking "my wife is 5' 7" what shoe size is she?"

Anonymous

godders wrote:

I want to order a new bike for the missus but not too sure what size she will need. She's 5ft 7 so the companies webiste suggests a 52 Small or 54 Medium. When I have worked out the frame size required using the inseam (80cm) x .67 this comes out at about 54. However I have worked out her top tube length using torso + arm length (as described in Zinn's book) and this comes out as needing a top tube of about 52cm making the XSmall 50 cm frame the best fit. I understand that top tube length is the most important so will probably go for the XSmall. Is this right?

By the way it isn't a women's specific frame.

Thank you

The top tube length as you say is more important that the seat tube length ( saddle height is easily adjustable and to a degree so is the handlebar height )
I presume the frame you want is only available in limited sizes so a cyclefit session wouldn't be much help at this stage.
It is better to err on the small side ;you can make a small frame fit using various seatposts and stem combinations but you'll never be able to make a frame that is too big smaller.

Down the Road

Anton de Lacey wrote:

godders wrote:

I want to order a new bike for the missus but not too sure what size she will need. She's 5ft 7 so the companies webiste suggests a 52 Small or 54 Medium. When I have worked out the frame size required using the inseam (80cm) x .67 this comes out at about 54. However I have worked out her top tube length using torso + arm length (as described in Zinn's book) and this comes out as needing a top tube of about 52cm making the XSmall 50 cm frame the best fit. I understand that top tube length is the most important so will probably go for the XSmall. Is this right?

By the way it isn't a women's specific frame.

Thank you

The top tube length as you say is more important that the seat tube length ( saddle height is easily adjustable and to a degree so is the handlebar height )
I presume the frame you want is only available in limited sizes so a cyclefit session wouldn't be much help at this stage.
It is better to err on the small side ;you can make a small frame fit using various seatposts and stem combinations but you'll never be able to make a frame that is too big smaller.

There fore if the shoes I want to buy are only available in a 6 or a 12 and I take a 10 I should shove my feet into the 6 rather than getting the correct size.

Muppet

Anonymous

Your signature is very apt.
Not really surprised that you relate bikes to shoes though,you seem to have an affinity to cobblers.

Cajun

with previous responses...
Personally I'd recommend that you spend a few quid and have her properly sized....that will be the best money you'll ever spend on her bike. If the shoe doesn't fit, it doesn't fit...same for the frame.
MAKE SURE THAT THE PERSON WHO IS DOING THE SIZING PROCEDURES HAS THE EXPERIENCE.....NOT SOMEONE WHO HAS DONE IT A 'FEW TIMES'.....

Anonymous

Cajun wrote:

with previous responses...
Personally I'd recommend that you spend a few quid and have her properly sized....that will be the best money you'll ever spend on her bike. If the shoe doesn't fit, it doesn't fit...same for the frame.
MAKE SURE THAT THE PERSON WHO IS DOING THE SIZING PROCEDURES HAS THE EXPERIENCE.....NOT SOMEONE WHO HAS DONE IT A 'FEW TIMES'.....

Reading the OP carefully it would seem that the frame/bike in question is only available in limited sizes .
If the OP had wanted to know about made to measure frames I suspect he would have phrased his question accordingly.
The advice A.dLacey gives, based on the information available is correct IMO.

Cajun

I didn't mean to imply 'made-to-measure' custom frame; only to determine what correct top-tube and seat-tube dimensions she should be considering for a comfortable ride. Knowing that, they could eliminate a lot of 'once-around-the-parking-lot' trials. Being measured for a pair of shoes doesn't mean that you're going to get m-t-m shoes.....just a starting point for a shoe that fits...and as we all know, shoe sizes vary greatly...a size 43 in brand A may not be a size 43 in brands B - Z...