Possible aero mods for conventional frame bicycle

[Grant-53]

The lower leg fairings are definitely worth developing. Upright Mike at recumbents.com has experimented with them and I have used barn boots in winter as well. The upper torso boat tail is also a proven design. The FIM limits its size on motorcycles and Triathlon sanctioning bodies have outlawed aero devices attached to clothing. A front aero water tank is permitted up to a given size. No ruling an rear water/food carriers yet.

The older gentlemen at the Vetter Challenge prefer a back angle close to vertical or slightly reclined. More progress is being made so check the latest post at craigvetter.com.

A bicycle fairing will be very similar in shape to the motorcycle fairing and 7/8 the size usually. The trick with a aero tuck is to have good fit and support of the chest and fore arms to reduce fatigue. I use a full face helmet with visor but a 'spaceman' bubble may prove undesirable when pedaling in warm weather. Anything over 30 mph (50kph) and I may install a lap belt plus skid plates in the fairing for my hips and shoulders.

[BamZipPow]

Originally Posted by parabellum

BamZipPow, thanks for the greeting. I have my account for a few years but I wasn't too active here, though.

It sounds like putting a well-fitted windshield can lower the power output by several watts, now I have to do it myself and check if it works that well for me (I ride almost only in the touring position, I don't do any racings).

These upper wheel fairing are really expensive, maybe doing your own fairing that are integrated with fenders and enclose the whole wheel (with cuts for brakes) would be a cheaper way?


Rumdog, I've seen that some of the pizza delivery men riding on scooters have rucksacks in a prolonged shape, maybe that would be a good base for making a kamback pack

Grant-53, I will surely make the read about the tail box, I'm riding upright so I have to check if it will work well in that configuration.

You could try building those items out of extruded foam/Foamular. It makes a fantastic platform to experiment with and you can easily shape fer yer needs. If you want to go even further, you will have a shape that you built to work from.

[botsapper]

Minimum prep, aero refitting yourself to the bike. Time trial bike aero tips for more efficient road bike riding.

Duathlon Triathlon bike fitting

http://a2wt.com/research.pdf

Ways to improve aerodynamics for timetrials -

Biggest Bang For Your Buck In Time Trial Equipment | CyclingTips

[Vman455]

Originally Posted by BamZipPow

...and more!
Upper Wheel Fairings are designed to give bicycle wind resistance the slip

How on earth do those weigh 2 pounds?

[BamZipPow]

Originally Posted by Vman455

How on earth do those weigh 2 pounds?

Probably from all the metall hardware...

[elhigh]

Originally Posted by BamZipPow

Probably from all the metall hardware...

I was thinking that between the added weight, the added stuff sticking into the wind in the mounting hardware, and the minimal coverage, those little skirts probably aren't helping much.

Parabellum, filling in the main triangle of your bike's frame is a good idea for minimal investment, just to feel how it might improve things. That is, unless you want to retain your water bottle mount. Or that's where some people clip a battery for a headlight.

Based on my limited experience of a stationary bike vs. my vast experience on actual bikes, try not to limit your exposure to moving air too much. If you build a fairing to cover most of yourself and the bike, leave a couple of ducts open here and there to provide a breeze on you. Even at modest rates of exercise you'll build up a lot of heat and if you don't have any airflow, you'll be pretty overheated pretty quickly.

One flow of air directed toward your chest and another at your groin will make a big difference in your overall comfort level, but that's a matter of personal preference.

[Vman455]

Originally Posted by BamZipPow

Probably from all the metall hardware...

There isn't that much to it, though--I count eight bolts, two rods, four plates, and the fairings themselves. To compare, this wheel:



...which is an aluminum box-section rim with a fairly substantial fairing, weighs just over two pounds.

Also, he shouldn't be claiming "up to 20 percent faster without any extra effort," when there was no controlled testing to generate that number.

[3-Wheeler]

Originally Posted by aerohead

.... This is something the Craig Vetter gang is missing on the Motorcycle Forum......

Phil,

Just curious. Has anyone from EcoM ever written to Craig and mentioned the Streamlining Template to him?

I noticed that many of the CV fairings, drop quickly behind the rider. And there is a reference to a aero specialist that gave mention of making the rake even steeper.

I'm at a loss on some of the things I've seen there. The overall premise of an airfoil around the rider is great however, and he gives great ideas on how to mount them.

Jim.

[COcyclist]

Originally Posted by parabellum

I would like to ask if there are any aerodynamic modifications that would do any good for a typical bicycle (in my case this is a diamond frame)?

Parabellum, I have been a bike commuter for roughly 40 years and an avid cyclist for much of that time. In my experience, anything you do to a diamond frame bicycle will have minimal effect on your commute times. I commute year round wearing bulky, baggy clothes in winter. The biggest drag comes from the rider. If you can get your upper body low and your back level with the ground that will make the biggest difference. You will decrease your CdA so a drop bar may be better than a flat handlebar. An "aero-bar" may get you even flatter but it is not practical to ride that way in traffic.

Anything you add to the bike may help in some ideal conditions but be a hindrance in everyday use. Bicycles are much more influenced by a crosswinds than are motorcycles. A 20 mph crosswind on a bicycle at 15 mps still feels like a nasty crosswind. A 20 mph crosswind at 60 mph on a motorcycle acts like mostly a headwind. Sailors talk of apparent wind, physicists speak in terms of vectors but you get the point. Many of the things that work for motorcycles could make you slower in the real world. Save up and build a tadpole trike velomobile as the ultimate commuter bike (or Human Powered Vehicle).

[aerohead]

Originally Posted by 3-Wheeler

Phil,

Just curious. Has anyone from EcoM ever written to Craig and mentioned the Streamlining Template to him?

I noticed that many of the CV fairings, drop quickly behind the rider. And there is a reference to a aero specialist that gave mention of making the rake even steeper.

I'm at a loss on some of the things I've seen there. The overall premise of an airfoil around the rider is great however, and he gives great ideas on how to mount them.

Jim.

I'm not sure for certain.
When Low & Slow came by a few years ago we talked about MC aero quite a bit and Vic is acquainted with the Template and also a friend of Craig's.
So I figure Craig has at least been exposed to it.
I think Craig has used symmetrical wing sections as a template,and I think it's more appropriate for bikes.
And with these 2-D flow shapes,we don't want to truncate them as we would a body of revolution.Any kind of pointed curve in the aft-body is better than a chop-off.
The Summers Brother's Goldenrod would be a good example.Walter Korff,who did the aero on this record car,found the tail so important that he enclosed the parachute tubes entirely inside a boat-tailed cone which could be shot off the car as a prelude to parachute deployment.
Last September,at Bonneville I was happy to see the Vesco family streamliner with this feature added finally,along with a few other teams.
I feel like Craig and his associates are on top of MC aero and have done well with their designs.
Here's one example of the clamshell rear

This bike would suffer larger drag with it's truncated tail

Here's the lowest drag 2D profile (in the center)

This table gives an idea for drag penalty when the tail is mutilated