Aerodynamics of thin steel tubes vs CF or AL

Discuss light weight issues concerning road bikes & parts.
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dvincere
Posts: 204
Joined: Fri Jun 01, 2012 6:40 pm

by dvincere

I know this is weightweenies but I was wondering if anyone has seen any numbers on the aerodynamics of a small tubed steel bicycle say against a monstrous tubed Al or CF bike? I was wondering how much one loses with something like my CAAD10 in aerodynamics against a more classic bike, considering only the frame. If we don't have numbers, any of you out there ridden enough bikes tot hink you can tell a difference?

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sungod
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by sungod

round section isn't a great aero shape, but most tubes are at an angle to the airflow (assuming headwind), so they present a more aero elliptical section, i'd guess a lot of frame drag is down to the headtube

rider size/clothing/position make a huge difference to drag, you'd need to measure a specific individual on different frames (and wheels) to see which worked best together, even then the results would only be for that person/position, and which frame is more aero may still vary depending on yaw angle

there're a few threads on ww about the aero frame topic, for instance...

viewtopic.php?f=3&t=106591

...contains links to some tests

dvincere
Posts: 204
Joined: Fri Jun 01, 2012 6:40 pm

by dvincere

Thanks for the link. I've seen a couple of these studies and they only ever compare carbon to carbon. I agree that round isn't the most aerodynamic shape with respect to coefficient of drag, but steel is capable of such a smaller frontal area to the wind at any yaw angle, that perhaps where trying to engineer ourselves back to where we used to be in terms of total frame drag. I'm a mech e but not in bicycle engineering so I can only make gross estimates to C_d and frontal area's... I do agree the rider will always be the most significant part of both the weight and aerodynamics equation, though.

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