Aerodynamics / Aerodynamic Cost / Aero parts

Looks like Zipp wheels can melt .. on EC1 collective bike in 3..2..1..

Its the humpback whale fin idea. The bumps don't help at 0 degrees, but don't add drag either because they are inline with the wind direction. But they make the humpback whale fin stall much less abruptly and at wider angles have a lot less drag ( and more lift).

look at this graph:

the peak and valley gets smoothed out

tldr: When the wind changes back and fourth over the stall angle (around 12 degrees in the example), it is much more controllable.

tldrtldr: The wheels handle better (if zipp got it right, no data yet...), and the idea should be put on 808s.

But what do they do at lower yaws where people who can ride (ie. non age-group triantelopes) are at?

Not much I would guess, the main benefit is making the wheel feel like a smaller rim depth (ei controllable) than it is.
In theory the wheels should get lower drag and even negative drag at wider angles, but that depends on zipps implementation.

The wheels also have fancy new dimples. These could lower drag at 0 degrees by keeping the air attached further round the rim shape, but no graph / data / comparisons yet

I hung on to my 808 when other people were getting off their bikes to drink because it was so windy in Borrego so I'm only interested if it's faster. I'm out. That's before mentioning the cost... and the hub recalls...

I hung on to my 808 when other people were getting off their bikes to drink because it was so windy in Borrego

To be fair, they were probably a lot lighter than you.

This was in the USA, you might be (somewhat horrifically) surprised.

haha yes 4000usd

its a bit annoying because I was (/am) working on sort of the same idea (#boastpost..):

Lower left corner: rough plastic print of a strip of bumps, to be smoothed with acetone and copied in a mold and cast in 40 pieces and glued on a aliexpress carbon rim. I based it on this research paper and guesstimated there should be 120 bumps 4mm high around the rim. Zipp seems to think 18-24 works best.

But hey, The research has been available since 2008/2004 and Zipp have been developing for years in windtunnels with practical examples. I just printed a piece of plastic and thought about maybe gluing it on a rim. What do they know? :)

edit: There was an earlier version but never backed up with data:

http://www.nottinghampost.com/dimitris-reinvents-wheel-bike-riders-edge/story-19350045-detail/story.html#ySmzW8HzqkgbXU9Q.01

editedit: image host is annoying. I have attached my photo:

1 Attachment

Damon Rinard/Nathan Barry/Cannondale Bicycles shared data from a windtunnel test of a bike with no brakes, rim brakes, disc brakes.

http://www.slowtwitch.com/Tech/Disc_and_Rim_Brake_Aero_Drag_6073.html

the comparisson between the rim brake and disc brake results is a bit unfair because the test uses the same wheels (with and without rotors attached). So a better rim brake setup would be with narrower nondisc hubs + 4 fewer spokes in each wheel.

They mentioned the wheelset choice in their statement of limitations.

The comparison is also not fair because they're using an aftermarket aero-specific rim brake versus a standard disc brake setup and they're using a 160mm front rotor instead of a 140mm.

They also appear to have tested without hydro lines or brake cables which would certainly make a difference.

Looking for a replacement TT frameset for next year, requirements are as below:

-medium-ish frame size ~52cm TT
-short head tube (ideally 100mm, maybe less)
-round steerer
-probably no more than £1200 (new or second hand, not bothered)

I currently ride an Argon 18 thing, it's a bit big and i run an adjustable stem pointing straight down to compensate as I ride with the bars pretty low. I'd like to get rid of this stem but it probably won't be possible...

Is a Cervelo P3 the best option? Or spend less on a frameset and spend money on other aero kit? (I already have a Zipp 900/808 combo, rotor aero cranks etc. and club skinsuits are hopefully going castelli next year, so that'll be as fast as possible) Cheers.

Is a Cervelo P3 the best option?

Probably. Ideally the proper one, not the 2013+ MAMIL version. With a £1200 budget you should have enough for a classic P3 and a 3T Ventus II

They won't use the Cervelos for sprint events.. and Trott will be on a UKSi bike too for the womnium/team pursuit. The team pursuit will also be on UKSI.

Sorry about the dredge, was looking for something else and stumbled on this.
"They won't use the Cervelos for sprint events." I think everybody except Hindes used the Cervelo
"Trott will be on a UKSi bike too for the womnium/team pursuit" Partially right, I think she used both in the Omnium
"The team pursuit will also be on UKSI" All four men and three of the women used the Cervelo

PX exocet2 plus 3t ventus bars could be a good option as well. Frames can be had for 3-400 and 400 for bars.

Spend the rest on an aerocoach session.

I'd love to test my Shiv vs. the P3 if everything else remained the same.

Cheers, this is the one were the seat tube matches the curvature of the rear wheel isn't it? Looks a lot nicer IMO.

Is the Ventus integrated stem only? I'm not sure if I'd be able to get the bars low enough as the P3 only looses me ~15mm of headtube, do you have any opinion on USE Tulas for this reason?

I'll post a picture of my current setup for reference when I get the chance...

EDIT
Current setup:

@danb Exocet 2 (I know to avoid the mk1) is a good shout, is there any data at all on it though? Aerocoach is on the to do list once I have a new frameset I reckon

Aerocoach is on the to do list once I have a new frameset I reckon

Better to Aerocoach before you replace your frame. If they move your position by much, it could have a bearing on which frame you buy.

https://www.lfgss.com/comments/13319139/

Just stumbled upon this in the HHSB thread:

Any thoughts on filling the spider vs. a Fibre-Lyte Total Aero chainring?

Filling the spider! DIY, and smoother airflow over the crank.
You can then buy a 'normal' ring, that you'd be able to sell to a wider audience when the time came to get rid.

Given that it's not part of the chainring, does that count as a fairing?

Although the actual rule basically prohibits everything aero so we're all fucked:
"The use of recumbent machines, protective shields, windbreaks or other means of reducing air resistance is prohibited."

Other than that aspect, Fibrelyte chainrings look about 300x better.

smoother airflow over the crank.

That's dependent on crank type and how good a job you do.
I have less material facing the air with a full aero Fibrelyte ring compared to that setup. But without testing both, who knows which is more aero. @xavierdisley probably but he sees the world in smoke trails...

There is that (and F-L are too busy too make me a Total Aero ring for 7400).

Off the top of my head I agree with you, that matching the arc of the spider arms is going to beat a flat infill.

@hippy As long as DIY mods/fairings are relatively subtle, i.e., not taken near NikB extremes, I don't see anything wrong with that.
Levelling the playing field with people who can afford fancier kit.
Far too many other holes in CTT rules to be an issue.

EDIT: I suppose becomes an issue at National & Worlds level though, so I do see your point.

I hadn't thought of that: fucksocks.

Anyway, I'm all about looking fast so I'll have to wait for F-L.