this post was submitted on 20 Sep 2024
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micromobility - Ebikes, scooters, longboards: Whatever floats your goat, this is micromobility

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Ebikes, bicycles, scooters, skateboards, longboards, eboards, motorcycles, skates, unicycles: Whatever floats your goat, this is all things micromobility!

"Transportation using lightweight vehicles such as bicycles or scooters, especially electric ones that may be borrowed as part of a self-service rental program in which people rent vehicles for short-term use within a town or city.

micromobility is seen as a potential solution to moving people more efficiently around cities"

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[–] [email protected] 0 points 1 month ago (2 children)

How would this reduce drag? Genuinely curious.

[–] [email protected] 0 points 1 month ago

Just guessing: trying to minimize vortexes and turbulences.

[–] [email protected] 0 points 1 month ago (3 children)

My understanding is that it has to do with form drag -- aka pressure drag -- which results in vortices forming in the "separation region" directly behind an airfoil. Or in this case, a rider. Essentially, the swirling of air behind the rider is turbulent -- which is why a hoodie might flop all over the place -- and that causes energy to be lost.

This video on Nebula (and YT as well) describes pressure drag at about the 02m30s mark for a sphere. But this graphic from Skybrary also shows the problem:

form drag

By providing a smooth surface for air to "cling" to, where it would otherwise form vortices in the separation region, should reduce form drag. Although it will cause induced drag (aka friction with the additional surface). But at cycling speeds, that's less a problem than it would be at airplane speeds.

[–] [email protected] 0 points 1 month ago (1 children)

So would this also reduce the benefits of "catching drift" behind another rider?

[–] [email protected] 0 points 1 month ago* (last edited 1 month ago)

This is a good question and I don't really know how this device would affect drafting and related manoeuvres. But if I had to guess, drafting behind a lead cyclist should still be beneficial, but the "zones" where it works might change.

So for example, the optimal distance lee-ward of a lead cyclist might become shorter or longer. Longer could mean more space to vie for that position directly behind the lead. But shorter might mean it's impossible to draft without crashing into the lead.

Side-to-side drafting distances might also be affected, like how birds travel in a vee-shape. Maybe the vee would become wider? That might not be beneficial, though, if it's so wide that it's impossible to stay on the racecourse.

TL;DR: I have no idea, and aerodynamics are hard. That's why I'm intrigued by the field.

[–] [email protected] 0 points 1 month ago

My genuine thanks for taking the time to craft your lovely reply.

[–] [email protected] 0 points 1 month ago (1 children)

Here's one site that has info on skirts (under the trailer to reduce side flow) and tails at the back. There's an image of a wind tunnel view that gives a good idea what it helps with. Those vortexes at the back of a flat trailer suck a lot of power.

image

[–] [email protected] 0 points 1 month ago

I'd much rather have my shirt going all floppy flappy in between the vortices and keeping my back cool than shaving 2 seconds off my relaxation cruises.

I know some people who would jump on this 100% and I should probably send them the article...