Pantani bike and aerodynamics

May 21, 2009
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I really enjoy the "retro" bike review of review of Pantani's 1998 "Bianchi". It was especially interesting to me how close it came to the present 6.8 kg limit. But I was surprised to read the following:

Convention was the rule back then, rather than the exception, with a standard threaded bottom bracket shell, non-integrated 1" head tube, telescoping 27.2mm seat tube, and well-proven tube shapes that ventured only slightly away from round in select areas. Needless to say, aerodynamics was barely even a concern a decade ago outside of time trials....

And later, in a photo caption:

The round seat tube looks decidedly traditional as compared to modern aero shapes.

"Modern aero shapes?" How is a 1.5 inch head tube going to be "aero" compared to a 1.0 inch head tube? Look at the bottom bracket of a Madone 6 or Specialized Tarmac or even the most recent pro bike reviewed by CyclingNews, the Kuota KOM. There's nothing "aero" about these frames with their massive cross-section of downtube and seat tube.

Sure, there's a few odd exceptions of guys on S-series Cervelos (even to this Sastre has shown considerable reluctance, preferring the fat-tubed "squoval" R-series), a few Felt AR's, and just this year the Fuji SST. But the majority of riders are on fat tubed beasts "stiffness über allis".

Neglecting the wheels, I'd be willing to bet the average Pro Tour bike (especially since this excludes Cervelo Test Team) is more wind resistance than Pantani's machine from 10 years ago. For what it's worth, the principal advance seems to be the stiffness, not aerodynamics.

One more comment: it's interesting so much emphasis is placed on the chainring choice, since these are swapped on almost a daily basis by mechanics in races. What's the last race the bike was ridden? So the choice of the 44 cog has little relevance.

Here he is in action on Deux Alpes:


Note the small ring is about as little as the BCD will support. That's no 44. Here's the 44 on it currently... compare and contrast:

 
Aug 13, 2009
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djconnel said:
I really enjoy the "retro" bike review of review of Pantani's 1998 "Bianchi". It was especially interesting to me how close it came to the present 6.8 kg limit. But I was surprised to read the following:

Convention was the rule back then, rather than the exception, with a standard threaded bottom bracket shell, non-integrated 1" head tube, telescoping 27.2mm seat tube, and well-proven tube shapes that ventured only slightly away from round in select areas. Needless to say, aerodynamics was barely even a concern a decade ago outside of time trials....

And later, in a photo caption:

The round seat tube looks decidedly traditional as compared to modern aero shapes.

"Modern aero shapes?" How is a 1.5 inch head tube going to be "aero" compared to a 1.0 inch head tube? Look at the bottom bracket of a Madone 6 or Specialized Tarmac or even the most recent pro bike reviewed by CyclingNews, the Kuota KOM. There's nothing "aero" about these frames with their massive cross-section of downtube and seat tube.

Sure, there's a few odd exceptions of guys on S-series Cervelos (even to this Sastre has shown considerable reluctance, preferring the fat-tubed "squoval" R-series), a few Felt AR's, and just this year the Fuji SST. But the majority of riders are on fat tubed beasts "stiffness über allis".

Neglecting the wheels, I'd be willing to bet the average Pro Tour bike (especially since this excludes Cervelo Test Team) is more wind resistance than Pantani's machine from 10 years ago. For what it's worth, the principal advance seems to be the stiffness, not aerodynamics.

One more comment: it's interesting so much emphasis is placed on the chainring choice, since these are swapped on almost a daily basis by mechanics in races. What's the last race the bike was ridden? So the choice of the 44 cog has little relevance.

Here he is in action on Deux Alpes:


Note the small ring is about as little as the BCD will support. That's no 44. Here's the 44 on it currently... compare and contrast:

Don't know about the aero but you know you are a player when you only have one water bottle cage on a big mountain day. Carrying bottles is for the little people
 
Aug 18, 2009
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djconnel said:
i really enjoy the "retro" bike review of review of pantani's 1998 "bianchi".

"modern aero shapes?" how is a 1.5 inch head tube going to be "aero" compared to a 1.0 inch head tube? Look at the bottom bracket of a madone 6 or specialized tarmac or even the most recent pro bike reviewed by cyclingnews, the kuota kom. There's nothing "aero" about these frames with their massive cross-section of downtube and seat tube.


For what it's worth, the principal advance seems to be the stiffness, not aerodynamics.

That's no 44. Here's the 44 on it currently... Compare and contrast:
+1, +1,+1, +1.
 
Sep 18, 2009
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it is not superseded technology

Well over 70% of wind resistance is the rider, not the bike.

In the peleton...irrelevant


Effectively Bike Performance has not moved on.

Carbon is a fetish
Aerodynamics on road bikes is
 
Mar 13, 2009
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The best carbon bikes are demonstratably lighter and stiffer than other materials. This is not a fetish, it became a fetish when punters decided all carbon is lighter and stiffer than aluminium or other materials. There are good carbons and bad. Aerodynamics in a road race...useful on a long solo break, the more people in the break the less useful. In a sprint what you gain in aero you could lose in stiffness.
 
Jul 5, 2009
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I've used a simple, coupled spring model to calculate the losses in a frame that isn't stiff. The numbers always come out to an order of 0.1%. So even if a new carbon frame is twice as stiff as Pantani's, at most they're saving 0.05% in efficiency. It also explains why Kelly was never hindered by riding his Vitus.

Aerodynamics on the other hand... I don't know of any wind tunnel comparisons, but given the size, frontal area, and aspect ratios I would imagine that the skinny steel tubes of yesteryear are more aerodynamic.

And as for light, well Pantani's bike seems to be bumping up against the UCI limit as it is.

The only improvement you could reasonably make on that awesome bike is to add some more aerodynamic wheels. Even for very hilly courses, the aerodynamic savings will trump any weight gain (Watts x time versus mgh).

John Swanson
 
May 21, 2009
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John:

Nice! Can you post details on your calculation? I didn't see it on your web site.

Stiffness is likely a matter of feeling secure rather than actual mechanical efficiency.
 
Jul 1, 2009
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Too bad they don't pump up the tires a bit or fill them somehow. It's kind of sad seeing them flat like that.
 
Mar 13, 2009
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ScienceIsCool said:
I've used a simple, coupled spring model to calculate the losses in a frame that isn't stiff. The numbers always come out to an order of 0.1%. So even if a new carbon frame is twice as stiff as Pantani's, at most they're saving 0.05% in efficiency. It also explains why Kelly was never hindered by riding his Vitus.

Aerodynamics on the other hand... I don't know of any wind tunnel comparisons, but given the size, frontal area, and aspect ratios I would imagine that the skinny steel tubes of yesteryear are more aerodynamic.

And as for light, well Pantani's bike seems to be bumping up against the UCI limit as it is.

The only improvement you could reasonably make on that awesome bike is to add some more aerodynamic wheels. Even for very hilly courses, the aerodynamic savings will trump any weight gain (Watts x time versus mgh).

John Swanson
John, I'm going to take a stab that you've only looked at hysterisis losses...if you can post a link I'd appreciate it.
 
May 21, 2009
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It will be curious when the Metrigear Vector comes on line whether this question can finally be resolved. I'm in the "low-loss" camp myself. It seems a flexy frame is a bit like elliptical chainrings. The pedal rotation rate becomes nonuniform, but in the end, work = ∫τ·dΘ doesn't change much through the system, where τ is the torque and Θ is the rotation angle at that point (pedals, spindles, crank arms, spider) (measured on a trainer to provide a firm frame of reference).
 

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