Aerodynamics / Aerodynamic Cost / Aero parts

Speed is not worth what's happened on this page

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Did someone say something?

Did someone say something?

It really sounded like someone said something. Hmm, might just be the 50Hz buzz...

Regarding Zipp's new disc disc, maybe they will start making centerlock track cogs :)

http://www.zipp.com/wheels/super-9----disc-brake-carbon-clincher-disc/#

Have Formula been reading my tandem thread?

No I think it was a one-off (at some time put on a raleigh fixed gear bike 2009). Can crop up on aliexpress (or thailand ebay..)

If we copy Team GB from the Olympics and start using big sprockets, we won't need centerlock anyway, 6-bolt goes down to 16T easily and 15T at a push.

Todd Reichert set a new world record yesterday, flying start 200m in under 5s. This is what really aero looks like:

How does he see where he's going?!?

Inside of the Aerovelo bike:

Really cool stuff.

How does he see where he's going?!?

Cameras:

Because of the enclosed shell, you use cameras and a TV screen to see where you’re going – that must be a bit weird?
Todd Reichert: It takes a bit of getting used to. It's kind of like playing a video game, except the consequences are a bit more real.

If he does crash I would imagine it would take about an afternoon before it finally gets to a stop on the tarmac. Would probably still beat world records on its side?

If he does crash I would imagine it would take about an afternoon before it finally gets to a stop

Rob English dropped one a few years ago, he managed to find a car to use as a brake
https://www.youtube.com/watch?v=i5Dapy1xUq0

More here: http://www.aerovelo.com/

It has some custom tri-/penta-spokes designed to be fast exclusively inside covers. It is nice that their design was proven correct. (I cant find which wheels they actually used, probably a trade secret...)
http://www.aerovelo.com/mission-log/2015/5/2/reinventing-the-wheel-pt-1-the-structure

Now they just need to retune the design for open air use...

I think it was either you or some internet engineering quote that stated that a chain drive should use minimum a 17 teeth sprocket. Efficiency should drop a lot below that.

There's 'discussions' on a Facebook track cycling group all the time about whether big-big or small-small is better. As best anyone can work out the minuscule efficiency savings from having the chain take a smoother curve round bigger sprockets is outweighed by the chain moving faster.

outweighed by the chain moving faster.

Eh?

GB use big/big, therefore it's probably faster.

As best anyone can work out the minuscule efficiency savings from having the chain take a smoother curve round bigger sprockets is outweighed by the chain moving faster.

Anybody who claims that is just wrong. There might be weight/aero arguments against big/big on a bicycle, but the raw drive efficiency argument is well understood both experimentally and theoretically.

chain drive should use minimum a 17 teeth sprocket. Efficiency should drop a lot below that

There's no hard cut-off, but efficiency fall off with reducing sprocket tooth count is non-linear, so you're getting onto a steep part of the curve somewhere in the low teens. Conversely, you're on the shallow slope pretty soon, so the gain from going from 48/12 to 60/15 is much bigger than the gain from 60/15 to 72/18.

All of the numbers are in marginal gains territory, if you get your chain set up properly you're talking about something in the region of 1W between 12 and 15 and another 500mW from 15 to 18 for crank speed of 100rpm.

The Diamondback looks cool!

Its great that bike designs are getting weirder again

Now there needs to be some comparative test that show what works ei:
Its best with a fairing close to the front wheel or to give the front wheel as much free space as possible....