Jacob’s Aero Bicycle Thread

[RustyLugNut]

. . . you have pictures!

As my wife likes to say, "I can't read, but I can look at pictures"!

[JacobLeSann]

A picture is worth a thousand words! Add in my mountain range of paragraphs and make it two-thousand words

[Should be biking]

Nice progress and I’m impressed by your sketches.
Your rear brake reminds me of the brake on the Zipp 2001.

[JacobLeSann]

I return!

Apologies for being sporadic. Made a lot of progress, then forgot about the bike, and now lately I’ve been doing quite a bit.

I’m using a styrofoam and fibreglass composite structure as recommended by my good friend. Stuff weighs nothing but I can punch it bare knuckled with no issue. I think I might try this design on car mods! It’s an enjoyable process, too. Glue the foam to the bike; shape it; glass it; rinse and repeat.

The design has also changed up quite a bit too. I became the new owner of a 2007 Aprilia SR50R. I can pin that scooter all day long and get up to 90 km/h yet the worst mileage I’ll ever get is 90 MPG. Averages 115MPG. $6 for me to ride 260-300km So, my usage of a road bike on the highway is effectively outmoded.
The bike is now being designed for more generalized riding, though mostly in town/city limits. As such, I’ve made the design more considerate of maintenance/weight/aesthetic factors. I like the turnout. I’m also tossing the cool Galaga-spaceship handlebars I made. They weigh like 7lbs (yikes!).

Will crosswinds suck? Very likely! I do not have a wind tunnel and have little knowledge on yaw angles in relation to drag. But as I have my scooter, this bike will be more of a toy/workout device than a necessity. Like a Porsche, except it’s worth maybe $200.


Enough yak, here’s some pics!

[JacobLeSann]

Slight update:

This bike is still alive. It has been unfinished for possibly 2 years now. Absolutely wild.

I did some very intense fab work to drop some weight off the bars, taper their cross section into a teardrop, and curve them carefully. I mistakenly ordered a fixed gear crankset which looked nice but doesn’t fit up with my gear. In addition, most of my group set just doesn’t mate well with the handlebars.

The verdict? I might just make it a fixed gear bike. I have better designs that will outmode it.

[Logic]

Aero bikes always end up going nowhere.

The reason:
They become downright dangerous and the rider either ends up dead, or having narrowly escaped with his life he vows to never get on that 'damn death-trap again!'
There's a good chance that that's what happened here too..?

The reason:
Aero is basically turning the whole frame into wings. Vertical wings..
Now wings are great at producing lift. Ask any aeroplane.
Or when you put them vertical a large amount of sideways force when the wind isn't from directly ahead:

Lets say there's a crosswind a couple of degrees from your left. (up to around 12 deg IIRC)
All those little wings are doing a great job of trying to pull the bike over to the right.
And that's fine; you just lean to the left into the wind.

But now the angle of the wind relative to the wing increases, you lean left more, and... suddenly the angle is too great (past 12 deg IIRC) and the wing stalls = loses it's push to the right, completely and suddenly!
But you're still leaning left. Either you go left, into traffic etc or fall over.

2 Solutions:

1: Make all the little wings weathercock around the original bars.
Now any cross winds affect you less than they affect a normal bike. (Safer)

In fact: If you spring-load them all slightly to want to face forward; any crosswind is turned into a bit of forward thrust for a very slight sideways/toppling force.
No more than you get from the stock round bars and likely still less.

2: So called Whale tubercles on wings increase the angle of attack range in which the wing produces 'lift' (to over 17 deg IIRC)
BUT most importantly;
makes the stall gradual (vs sudden)
That means that you have time react: To correct for all your leaning to the left.

The other thing cyclists vehemently choose to forget (for fear of looking naf/stupid/unlike the other sheep) is that the top (~3rd) of their wheels and tires are moving upwind at twice the speed of of the rest of the bike.
Any aero mudguards always get boo'd at, if not tarred and feathered and chased outa town!

Hopefully that will change thx to the aero work happening on race motorcycles nowadays. But it takes almost zero brainpower to pedal so who knows.

[Grant-53]

I made my aero bars using a pair of end bar grips, four 300 mm pieces aluminum 25 mm angle stock, and two pieces of 22 mm tubing 100mm long. Bond the aluminum angle stock to form a T shape with the lengths offset about 25 mm. Drill two 6 mm holes through both the bar end and the angle pieces. Notch the 22 mm tube so it fits flat against the longer of the T pieces. Assemble with 6 mm bolts and nuts. Attach to a flat handle bar 125 mm either side of the stem. Adjust so your elbow should rest comfortably. Put grips on the vertical tubes andany cushioning on the top of the T sections.

A small front fairing cut from a piece of corrugated plastic 600 mm by 900 mm. Cut slits toward the center in a radial pattern. Overlap at each cut about 30 to 40 mm to form a concave shape. Secure by punching holes through both layers in pairs 25 mm apart and thread small zip ties. Mount a length of angle stock to the head tube with a muffler clamp. Attach the concave piece to the angle boom and cross brace with pieces of cord attached to the top corners.

The tail section is a 900 mm cone of sheet material that tapers from the hips to a point. Mount to an aluminum angle piece clamped to the seat tube. Hoops of plastic tubing can be used inside the cone to maintain the shape if needed. See the photos of the Rocket tailpiece by Oscar Egg

A wheel cover disc is safe to use only on the rear wheel. ANY FAIRING MUST BE ATTACHED TO THE FRAME AND NOT THE STEERING COMPONENTS. This will prevent crosswinds from affecting the steering control.

[Grant-53]

A full fairing system on a road bike should be similar to naked recumbent. See recumbents.com building body shells.