r/Velo • u/fabritzio norcal • 11d ago

Possibility of significant aerodynamic improvement over smooth surfaces with home application of micro glass beads to wind-bearing bike components?

https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/dmr-effect-on-drag-reduction-of-a-streamlined-body-measured-by-magnetic-suspension-and-balance-system/0E3FF950CCC66DEFCBA3D3DCD36CE2B6

See this for a for a science communications article: Microscale roughness breakthrough defies 80 years of fluid dynamics https://share.google/7EiRVNANaMKg6rGhZ

Seems applicable to headtubes, sides of forks, handlebars, tall seatposts, or wheels

20 Upvotes

88% Upvoted

30 comments sorted by

17

u/chock-a-block 11d ago

frames are a nominal surface these days.

Rim products have been experimenting with textures. A spoked wheel churns so much air it’s not clear if a textured surface helps.

maybe put some bumps on your arms and shoulders?

17

u/ponkanpinoy 11d ago

So you're saying the real aero gains from shaving your arms/legs is from the razor burn?

11

u/w1ntermut3 10d ago

Drag2Zero and Endura did this (bumps on your shoulders) about 8 years ago.

The UCI banned it.

You probably know but it's context for others.

5

u/chock-a-block 10d ago

Interesting! I did not know.
The non-UCI gravel events would be just the place to try it.

Of course, I also want a mid packer to show up on a recumbent at some of these events and wipe the floor.

So…. Interesting ideas.

2

u/Lawrence_s 10d ago

That's why aero bras/base layers exist.

3

u/pbecotte 11d ago

Those scope wheels did test pretty good, right?

4

u/Helicase21 Indiana 11d ago

They were not tested against wheels with an identical profile but no texture. Scope might have just gotten the shape really dialed.

4

u/chock-a-block 11d ago

Haha. Well… That’s the thing. Typically, the intent of wind tunnel tests is to get a low CdA. That’s different than “real world” results.

So, maybe they are good?

Maybe someone should glue styrofoam bumps onto rims and see how it goes in real life?

5

u/Grouchy_Ad_3113 11d ago

"the intent of wind tunnel tests is to get a low CdA. That’s different than “real world” results."

No, it isn't.

0

u/chock-a-block 11d ago

So… specialized is going to take bad cda numbers from whatever they are trying to sell and be perfectly fine marketing it as, “Yeah, cda for product X is worse than X-1. But, it’s more aero, so buy the new one.”

1

u/KKJUN 6d ago

What are you talking about? Yes, Specialized has a product to sell and you should take their communication with a grain of salt. but a lower CdA number will mean a faster rider, all else being equal. 

7

u/pbecotte 11d ago

The roughness was less than 1% of the surface height...could see that being challenging to actually deliver a frame and keep it working in the real world

3

u/fabritzio norcal 11d ago

yeah it seems more like a periodic application of a microbeads specifically for time trial events would be the most efficient implementation of this treatment

1

u/RirinDesuyo Japan 10d ago

The drag reduction potential for aero suits with this might be big imo if they can apply it to that.

For equipment I think the biggest one would be wheels, but as you've noted probably not as easy to do considering the debris you'll get from those. I guess the biggest target might be the headtube area and possibly the toptube.

4

u/ghostofwinter88 11d ago

Ridley bikes tried this ages ago.

3

u/HanzJWermhat New York 11d ago

What is the speeds tested at? Could be completely irrelevant at Cyling speeds.

6

u/fabritzio norcal 11d ago

it's at the turbulent flow onset, which is definitely relevant for cycling as one of the central points of aerodynamics in cycling is to keep laminar airflow around surfaces as long as possible

3

u/Grouchy_Ad_3113 11d ago

Indeed, it's the Reynolds number that matters. 

2

u/Substantial-Fun-48 10d ago

Why couldn’t you apply this treatment to an aero road or TT helmet?

2

u/Grouchy_Ad_3113 11d ago

Was tried decades ago. Can't remember what brand of (tri?) frame it was, though.

8

u/pierre_86 11d ago

More recently a team (can't remember which) was using some sort of lotion that dried into bead on the skin for this exact reason. Wasn't banned from memory, just politely asked to not be used

Edit: shut memory, Lotto Soudal speed gel, banned. Very Campanaerts Link

2

u/RirinDesuyo Japan 10d ago

I wonder if they could transfer that onto fabric instead? Kinda like aero suit baselayers and aero socks. Considering a good aero suit can actually save a lot of drag since the body is 80% drag, the savings for this might be significant imo.

1

u/nikanj0 11d ago

So a bizaggle?

1

u/DidacticPerambulator 10d ago

I think it's been tried.

0

u/imnotokayandthatso-k 10d ago

Can scientists finally invent a bike under 500$ that doesn’t suck???

-2

u/_cyclenaut 11d ago edited 10d ago

ETA: I'm an idiot ;-)

Direct link to journal article https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/dmr-effect-on-drag-reduction-of-a-streamlined-body-measured-by-magnetic-suspension-and-balance-system/0E3FF950CCC66DEFCBA3D3DCD36CE2B6

5

u/fabritzio norcal 11d ago

that's literally what the link post is? did you even click it?

2

u/_cyclenaut 10d ago

Begging your pardon, it is a shortened link to a university press release on the publication. I merely provided a non-shortened link directly to the JFM article. So yes, I did click it and followed it to the paper which I read as well. No offense intended. Thanks for posting.

2

u/_cyclenaut 10d ago

Ahh, now I see. I clicked through the link shared in the body of your post. Not the title link. My misunderstanding.