Search Dave's Bike Blog

 Watch Dave's hilarious Ass Song Video.

Or click here to go direct to YouTube.


A small donation or a purchase from the online store, (See above.) will help towards the upkeep of my blog and registry. No donation is too small. $1 or $2 is much appeciated.

Thank you.

Email (Contact Dave.)

  If you ask me a question in the comments section of old outdated article, you may not get an answer. Unless the article is current I may not even see it. Email me instead. Thanks Dave

Join the Registry

If you own a frame or bike built by Dave Moulton, email details to list it on the registry website at www.davemoultonregistry.com

Infographic

Dave Moulton


More pictures of my past work can be viewed in the Photo Gallery on the Owner's Registry. A link is in the navigation bar at the top

Bicycle Accident Lawyer

Zero Tolerance for Spam

  I can delete Spam a lot quicker than it can be posted. Comments are checked daily, even on old articles, and any with irrelevant advertising links are deleted. Blatant or persistant Spammers are blocked. 

Dave Moulton

 

 

 

Powered by Squarespace
« Please, just go around me | Main | Rescue Bike »
Wednesday
Jan072015

Designing Bikes for Women

I have this theory regarding functional art, that if an object or piece of equipment is designed to perform its function correctly, it will appear pleasing to the eye from an aesthetic point of view. A piece of furniture like a chair, a bridge, a boat, or indeed a bicycle, all fall into this category of functional art.

Not only does the bicycle need to look right standing alone, but rider and bicycle need to look right together. The bicycle becomes an extension of the rider, a platform if you will for the athlete to launch a physical effort.

As a result of my last article, a story of the above track bike, the bike’s former owner, Maggie Thompson, formally Margaret Gordon Smith, commented on the piece, and sent me the above picture, of her actually racing on the track in the British National Women’s Pursuit Championships.

Rarely do I get to see a perfect side on photo of a rider and bike, where the rider is at maximum speed and one can see how well rider and bike fit together. For those who don’t know what Pursuit Racing is about? Two riders start on opposite sides of a banked track or Velodrome, and they chase each other. Hence the name Pursuit.

It is a race of truth, like a time trial, there is no pacing. The winner is the rider ahead at the end of a set distance. The women’s pursuit is 3,000 meters, which is 3 kilometers, or 1.863 miles. Not a huge distance, but one starts out about half a lap out of the saddle to reach maximum speed, then sit down and try to maintain that speed to the end. It is a race that will leave you gasping for breath for an agonizing 4 minutes.

Maggie describing this bike said, “I found I could breath.” That was because the rule of frame design back in the mid-1970s and before, was a 73 degree seat angle for everyone no matter how tall or how short. Maggie is slightly over 5’ 3” tall, which is not unusual. Many women are in the 5 foot to 5 foot 4 inch range.

This frame had a 77 degree seat angle which was unheard of at the time. But while 73 degrees is fine for a tall person with long legs, for the shorter rider it means the thighs are pressing tight into the upper torso thus restricting breathing. Of course it is essential the back be horizontal for maximum aerodynamic efficiency, and the steeper seat angle cuts down the angle of torso bent at the pelvis. It also allows for a shorter top tube meaning the rider is not stretched out, and the arms are working in opposition the legs.

Right: Maggie on her road bike I also bult for her. This frame had a 76 degree seat angle.

When it comes to designing and building bikes for women, it is not that women are drastically different proportionally than men, it is that they are generally a lot smaller.

It is a myth that all women have longer legs and shorter bodies.

Women come in all shapes and sizes the same as men, long legs short torso, short legs long torso.

The main difference being, shorter overall height and much smaller feet than men.

The length of the foot comes into play because when pedaling the toe is pointing down at the bottom of the pedal stroke, so the foot becomes an extension of the leg. A man and a woman of the same height and leg length could both use an identical frame, but the female rider would have her saddle set lower because of her smaller feet.

The problem frame designers and builders have always faced when it comes to building bikes for women, is in making bikes small enough. There is a limitation caused by the wheel size. In the last 60 or more years I have been involved with racing bikes, (And before.) they have had 27 inch wheels, the wheel diameter to the outside of the tire is 27 inch diameter, or slightly less depending on the tire cross section.

700C wheels are the same, 27 inch diameter or slightly less. I always thought the “C” was for Clincher, but I have noticed tubular tires are now also called 700C. A front fork has fork blades that are the same length no matter how large or small a frame is, because the front wheel is the same 27 inch diameter for all sizes.

Throughout the range of frame sizes, the fork crown stays in the same place. So does the bottom headset bearing, and in the days of lugged steel frames the bottom head lug was always in a constant position.

Everything above this point varies with the frame size. The length of the fork steering tube, the frame head tube, the top tube is higher, etc., etc. In the days when top tubes were always level, the framebuilder could only lower the top tube until the top head lug met the bottom head lug.

Metal could be removed from the top and bottom lugs but for all practical purposes the smallest frame one could build with a level top tube was 48 cm. (19 in. C to T) with a standard bottom bracket height. After that one could raise the bottom bracket to make the seat tube shorter, but the last thing a rider with short legs needs is to be higher from the ground.

Incidentally in the top picture, Maggie’s track frame is 19” but the head lugs are not touching. That is because track bikes have a higher bottom bracket to clear the angle of the track banking. Also the steeper than normal seat tube pushed the seat lug higher, and therefore the top tube.

Today’s frame design with the sloping top tube does make it possible to make much shorter seat tubes. However, the front end stays exactly where it has always been, because the front wheel is still the same diameter. The good news is, shorter riders do not need a huge difference in saddle to handlebar height. See how little difference there is in the top picture of Maggie on her bike.

My advice to a female cyclist who wishes to engage in serious competition. If you are 5’ 6” in height, or taller you can ride a men’s frame, bearing in mind what I said earlier about your saddle being lower because of your smaller feet. If you are shorter than 5‘ 6” and especially if you are in the 5 foot to 5’ 4” height range, get the smallest frame with the shortest top tube you can.

There are frames out there that are advertised as being Female Specific. These have a longer head tube resulting in a higher front end. There is less drop down from the saddle to the top of the handlebars, making for a more relaxed position. These are great if you just want to ride for exercise or engage in ultra-long distance rides. There are similar frames for men with names like “Endurance.”

Whether male or female, choose a bike or frame that suits your purpose. If you want to race seriously get a race bike and set it up in an efficient aerodynamic position. If your goal is exercise and more leisurely riding, don’t buy a race frame, buy one of the bikes offered for that purpose.

 

 To Share click "Share Article" below

Reader Comments (11)

700C actually refers to an obsolete French standard. All the "700" sizes were the same nominal outside diameter (700 mm) and the letter suffix indicated the tire width. Wider tires necessitated smaller rim diameters to maintain the same outside diameter. 700C was the only one to survive and is now an ISO standard.

http://sheldonbrown.com/tire-sizing.html#french

January 7, 2015 | Unregistered CommenterKeith

Keith,
I stand corrected regarding the "C" standing for Clincher. But 700mm outside diameter is 27 9/16 inches, that would not fit in my frame. Through the 1970s and into the 1980s I built my frames with clearance for 27 inch Tubular tires, which on average measured 26 3/4 in. dia. Narrow 700C tires were about the same. Now I use the wider 25mm. tires and they measure 27 inch, as close as I can measure with a with a regular steel tape.
I knew if I said 700C were the same as 27 inch someone would call me on it, which is why I tried to give some explanation. I built my frames for 27 in. wheels, and so did every other framebuilder world wide. 700C fit in these same frames, so as far as I'm concerned they are the same. Please, please don't let this degrade into a discussion about tire sizes, it is not the subject of the article.
Dave

January 7, 2015 | Registered CommenterDave Moulton

Hi,

As you mentioned, your words can be extended to everybody, not just females :-D. I am a ~5'3" male and this article says what I have been doing for a lot of time but I haven't found elsewhere: If you are small, get the smaller frame you can find.

It is difficult to find non-custom frames with short top tubes (under 525/520 mm) and sloping top confuses that measure (you have to find the "effective top tube" or something similar to check it).

I thought about "women-specific" bikes/frames but, as you say, they make the problem worse. They have longer effective top tubes with shorter seat tubes and this is generally the opposite to what most "short" persons are looking for (either male or female).

Regards,
Pedro

January 8, 2015 | Unregistered CommenterPedroMJ

"Please, please don't let this degrade into a discussion about tire sizes, it is not the subject of the article.
Dave"

No, it's absolutely not the subject of the article. If anything, the subject of the article could be the smile on Maggie's face in the lower picture. Sure, it might be staged... but it might be the joy of riding a bike that actually fits. Well done, sir.

January 8, 2015 | Unregistered CommenterPlain Jim

As always you write interesting articles. Thank you for sharing.

January 8, 2015 | Unregistered CommenterChris Bernique

I wonder where Maggie's road bike is now? Does she still have it?Hopefully it didn't find its way into another tip. :-(.

January 8, 2015 | Unregistered CommenterJW

Interesting looking at the top photo and seeing the position of her knees and arms.She must have used a wider bar to bring her arms out wider to miss touching her knees? This was caused in part by the steep seat angle, bringing the body more forward. I have had a similar problem on my 1953 Rotrax with the TDF bars that are narrower and have a short forward reach. When getting out of the saddle to sprint I can touch my knees with my arms. By the way Eileen Sheridan was always smiling and happy on her bike. If you go onto www. merriemaggie.co.uk and listen to the tape of Maggies interview with the BBC you will see why she is called Merrie Maggie. I ave not heard a laf like that for some time. GREAT STUFF!

January 9, 2015 | Unregistered Commenterjohn crump

Dave,
A few of these fit rules apply to older riders also. I can't tuck as low as I used to. I have found myself moving back to very steep frame angles and very short stems.
Building a frame at 76/73 would fix that issue even in a taller frame.

I have always had to watch the 'elbow/knee' clearance. It takes twisting the cleats a bit to force you to keep your knees tucked in like they are supposed to be.

January 14, 2015 | Unregistered Commenteredstainless

Dave, Every night I would get back problems. I got a riser stem, No more problems. My Concorde Xblade C/F had the head tube cut short so this was about the best way to reaise the bars a tad.

January 19, 2015 | Unregistered Commenterjohn crump

Hey Dave! Do you have the original resolution of the second picture in this article? I'd like to post it to my tumblr blog, but the cropped version you have here would distort on tumblr if I were to post it.

April 9, 2015 | Unregistered CommenterKel

You're one of the few framebuilders or bike fitters that regularly remind us that people come in all shapes and sizes (and also factors in foot sizes). In many cases, gender-specific bike kit is just marketing.

Regarding the height of the top tube - as a tall rider not getting any younger, I find my older classics with downtube shifters become more of a stretch and less comfortable to use. How nice that technology was invented to help me :-)

June 14, 2016 | Unregistered CommenterSteveP

PostPost a New Comment

Enter your information below to add a new comment.
Author Email (optional):
Author URL (optional):
Post:
 
Some HTML allowed: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <code> <em> <i> <strike> <strong>