Thanks for writing. I'm not just talking about how the lower BB would affect the the frame, but also, the absolute height of the rider from the ground, which would be reduced. If frontal area is height/width, then surely being lower in absolute terms, equates to a lower frontal area???

For instance, if we took a guy who rides 150 cranks - there was a recent thread on this - then if we custom built him a frame with a super low BB to take advantage of the short cranks (with the reduced amount of clearance required for pedal strike) then he would get quite a significantly lower absolute position, and hence, frontal area. Surely, that would be quite significant??? Or am I still missing something?

"then he would get quite a significantly lower absolute position, and hence, frontal area. Surely, that would be quite significant??? Or am I still missing something?"

yes. you're missing the test. we're having a discussion now on which side of the bike presents better to the wind in a yaw. the result is completely (to me) unintuitive. bikes do not always behave as you suspect they would.

as to 650c wheel bikes, the reason you don't lower the BB as you suggest is because the point (my point) in making 650c bikes was to fit and handle properly. i believe my BB drop in my women's specific bikes was 45mm or so. i started building these in 1988, and it's an absolute crime that the bike industry has allowed these bikes to fall out of favor. with all the discussion of women's proper and equal treatment in sport we've had over recent years, this is one that these equality and access movements have not been nuanced enough to understand.

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Dan Empfield
aka Slowman

It's not mind boggling though, because we're talking about a small minority of the market that would require significant investment to properly serve, fair or not. The world's leading fitters may be lamenting the demise of long and low, but the other 95% of fitters who don't know what they are doing are perfectly fine fitting/recommending bikes that are far too tall for that small minority. I went on a rant about this a while back in the 'why are women's bikes more expensive' thread.

You must be Dutch if you think 5"1 is a small minority of the market. Or, just a blind male.

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ZONE3 - We Last Longer

You must not have read the link.

Actually, no.

Take a look at a frontal picture of a cyclist. The overwhelming majority of the frontal area is the rider. The bike makes up a small fraction. Moving the "blob" that consists of the rider up and down (keeping the body position constant relative to the BB) doesn't change the contribution of the rider to the frontal area one iota.

All you end up doing is exposing or covering a very small portion of a very small contributor to the total frontal area, especially for the BB differences being talked about here. So, it basically doesn't make an appreciable difference in this case.

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http://bikeblather.blogspot.com/

I did. You really do sound like an MBA textbook cliche.

More and more women cycle. Women's pro cycling is on the rise. Companies market for women, advertise for women, and yet - if you're a 5"1 female which is the global average, you'd be hard-pressed to find a tri bike that fits. Regardless of price or gender-designation, because there is no "male SKU" to substitute. A business manager who chooses to ignore a quarter of the potential customers is doing a pretty bad job - and sponsorship and other up-front investments in male cycling are still way, way larger. I wager you've never discussed sponsorship costs with a male pro team, have you?

I don't care if it's labeled male, female or orc. I want to buy a bike that allows a 5"1 person, who needs a pad stack in the 490-530mm region, to ride a position as optimized as a 5"9 person could achieve.

Of course, all this started when I asked how come a bike company announces a frame size, prides itself on that frame size (just see how much of the Liv Avow material refers to that small front wheel), and then doesn't let national distributors order that size.

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ZONE3 - We Last Longer

I think it's because they don't care about serving the <5% of the market who KNOW they need a stack that low. The worlds best fitters may know, you may know, but it's still a sliver of a sliver who are actually butt hurt about this.

Also, marketing. Giant touts "women's specific geometry" as an advertising principle, not as a fit principle. They fail to mention that the geometry is the same as the men's on the rest of the line...

Last I checked, the Avow comes in a different range of sizes than the Trinity which caters to smaller women. Their marketing blurbs are all about the extremes they went and how they realized the XXS needs a 650c front wheel. The Liv Envie has a different geometry than the Propel, too, as do the other Liv bikes and their Giant counterparts.

You know what? You're wrong. It doesn't matter whether you're a die-hard bike nerd who aero-tests his equipment, or a complete beginner. If you can't swing a leg over the top tube without impaling yourself on it, you won't buy that bike. Same if you can't reach the handlebars comfortably. You're getting hung up on that one long-and-low comment, but I'm talking about those who need short-and-low. You know, women. Just on my team, we have four girls who haven't bought a TT bike because they can't find that fits, and a few who bought a bike too big for them because "it's still better than none".

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ZONE3 - We Last Longer

Emotional much?

No, quite calm. Nice job assuming, though.

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ZONE3 - We Last Longer

The Cervelo P series 45 doesn't work for them? The Trek Speed Concept XXS is also really small but unfortunately Trek now only offers that in the pricey 9.5 model. My wife is 5'0" and bought a first generation Speed Concept 7 and it fits her just as well as her custom Seven, it has a very short reach..

I wasn't at Cannondale when the new SuperSix EVO was designed, but check out row K, BB drop:

It varies with frame size, in step with expected crank length.

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Yeah, my mum has the old SC 7 and it's a great fit for her - if we could locate another one it could be a match. Cervelo would be an option but right now the local distribution switched hands to a shop I'd rather not rely on.

That being said, I've found that Orbea and Canyon (again, like Felt, two brands with no local presence...) manage to make super-low 700c bikes with a pretty short reach, too. Worth a look.

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ZONE3 - We Last Longer

With regard to the pressure of 80psi...I don't know anyone that can ride 80psi on 650's and not pinch flat, even some of my 115 lb friends.

I don't know exactly what it is but I can ride 85-90 psig all day long on my 700C road bike with no issues but I'll flat on my 650 bike. That is my experience using the Pro4 race and Conti 4000SII tires

Not everyone that rides 650 wheels use 160-165 cranks. I know the trend is going that way though, personally I dislike anything shorter than 170 (yes, I spent a considerable amount of time on them) and have thought of going longer.

There is no need to drop the BB 5mm. People that need that small of bike (smaller than 48cm) don't punch a very big hole in the air anyway. I would rather have the pedal clearance above the ground.

What did you use on the front end of the P3?

I'm at a pad stack of 500 right now and don't need to go lower but my P2 is capable of it, I was just curious of the front end components you used.

FSA Sl-K -20 stem - the design means it's lower than a standard stem with -20 angle would be
Vision clip on bars
Slamthatstem cover doesn't fit the headtube diameter perfectly, but you well know that every little counts in getting low

Can you influence Cannondale to make a real 650C road racing bike?

Thanks, I'm on the Vision clip on bars as well but am using a PD Prosvet basebar so I could take out the last 12.5mm spacers from under the pads and use the teeny tiny ones.

I haven't needed to go as far as using a slamthatstem cover yet, I did on my old P2. I have a COBB spacer on another bike that looks to be a better fit although it's 2 or 3 mm taller and that may not be an option.

I'm going to look for that stem, I'm currently using a Performance bike adjustable. It's OK but I'd like to get away from it.

jaretj

Any idea how low one can ride on a tubular 650?

I'm 158lbs and ride 90 psi without any problems. I'll try lower in the next few weeks to see what happens.

Thanks for posting. Yes, my CAAD 9 does exhibit the same BB difference, but the problem for me, and where this stems from, is that my saddle height (I have a 48 cm) is not determined by optimal fit, but by the necessitude (certainly in my opinion) of being able to touch the ground with at least even the tip of my toes. Sure, it's not a problem when racing, but for general riding, I don't consider it safe. (I have short lower legs and a long torso.) So despite the added advantage (in terms of lowering the saddle height in absolute terms) of riding midfoot, my saddle height is still a fraction lower that what it would be if the bike had a lower BB. So please, lower them a fraction further on the small sizes ;-)

In reference to JaretJ's comment, it is not all about pedal clearance.

Thanks for explaining. Sure, the frontal area of the big blob wouldn't change, but I'll take your word that the reduction in the frontal area of the thing under the blob (from being shorter, in terms of absolute height of the bike) would be insignificant.

There is one more question I have, if you could get the rider lower to the ground in absolute terms, would there not be a benefit from the reduction in wind speed from being lower? Or again, would that be insignificant?

I am confused, so you want to be able to put a foot on the ground, while still sitting on the saddle?

In still air, no difference, since the apparent wind gradient is basically zero in the vertical direction. With any ambient wind, there would be a small effect since there is a non-zero velocity gradient in the air flowing across the ground (i.e. zero at the ground surface and then increasing quickly)...but again, the differences in height of the "blob" we are talking about are not enough to make an appreciable difference due to this effect. So, in theory there is a difference...but in practice, it will be basically immeasurably small.

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http://bikeblather.blogspot.com/

I think Tubulars are a different animal than clinchers when it comes to pinch flats, those are the kind of flats that are most common to me.

Now it's been several years since I raced on tubulars. Back then I was on TUFO, then Conti Competitions then Vittoria Corsas.

I thought the Corsa was narrow for 90 psig but I was on the high inflation pressure train back then and rode them at about 120psig.

If I was riding tubulars now I think I'd be nearer 100 psig, most tires feel fairly soft to me at that pressure and that is just under what I ride on clinchers, (I'm about 142lbs)