Friday, November 23, 2012

Bike builders news November 23

Feature article by RadicalBrad of Building a Velomobile - Part 2

In this week's issue, Brad makes a scale model of the velo body shape and design considerations.


Hub flanges and axle adapters for your bike projects
Bike builders community chat
Bike builders gallery - new additions: recumbents, trikes, choppers, tall bikes, kids' bikes, cargo bikes & more 

This and archived newsletters are here.


Thanks for your feedback, and keep those suggestions coming.

  See you in the Builders Forum.

Monday, November 19, 2012

Most cost-effective currently available lithium battery source and/or configuration

From the AtomicZombie bike building forum:

"Well, another spell in the repair dock gave me more time to think about possible add-ons (or more correctly build-ins) to the Timberwolf languishing in what I laughingly call my workshop. I've been giving a lot of thought to various possible additions to Brad's basic design, including a geared mid-drive, but mostly about how best to incorporate electric assist right from the get-go.

The logical first idea is to use an electric hub motor on the front. This has the advantage of simplicity, but on the other hand, it puts the motor at the part of the trike where ground contact weight is lightest. I don't know how much of an issue this will be, but its fair to say that the majority of the weight in any of the Deltas is carried at the rear, and so traction at the front wheel is a question mark.

The second idea is to use one, or two, Currie-style external motors either directly driving one or both rear wheels, or else connected into the chain/derailleur drive train at some point between the pedals and the rear axle.

However, the biggest single consideration is batteries. I have the wreck of an e-scooter that will, I hope, become a tadpole recumbent trike at some point; its all-up weight without passenger is over 200 lbs, and of this probably 2/3 is lead-acid batteries. I just can't see building a Timberwolf, which with rider will mass somewhere between 135 and 150 kg., and then adding a great whacking load of lead-acid batteries. Even if the tires would stand up to the load, it would be a tremendously heavy vehicle.

So, we then come to the lightest currently available battery technology, the various lithium-based types. These have an astonishing power-to-weight ratio, but they are new technology, and as such there's a lot of mis-information floating around. There's also the question of cost: what form of lithium cell offers the best "bang for the buck" in terms of watt-hours stored vs. dollars (not forgetting overall weight).

It's a basic truism that for a given power rating, using a higher voltage means a lower current draw. Since with most types of batteries the rate of current draw or discharge is a big factor, using a higher voltage would allow the use of cells with less amp draw capability.

The brick wall that I keep coming up to, and banging my head against is this: What form of lithium pack is the lowest cost for a given current draw, and what form of lithium battery is the most flexible in terms of series-connecting the packs to achieve higher output voltages. I have read various "opinions" and "reports" until I'm drowning in hyperbole, and I'm no closer to the answer: what's the best available form or configuration of lithium battery to start with.

For example, there are a wide variety of lithium cells used in RC model aircraft, robots, etc. There are any number of different lithium cells available for commercial-grade power tools. There are lithium batteries available in various ratings for laptop computers - and the list goes on. The common denominator is that they're all expensive, and so if one is going to bit the bullet and invest in a lithium battery system as an integral part of the build, it would make sense to try and maximize the power storage capacity and ease of recharging for a given dollar expenditure.

Once upon a time, I had a shingle that said I knew something about electrical engineering, and I suppose I still do know some parts of it. But I'm having tremendous difficulty in separating fact from hype in discussions about lithium technologies, and even more difficulty in finding out how best, and from whom, to source the batteries for the least cost without buying junk.

I've considered other options, from lead-acid, NiMH, Nickel Cadmium, etc. - and all are expensive if purchased new. So although lithium technology is expensive, any discussion of cost vs. weight vs. energy storage capacity has to take into account that, unless you stumble across a free or very cheap source, the battery pack is going to be the largest single expense in an electric drive system for a bigg-ish delta trike. Even if motors are purchased new, controllors likewise, the battery is going to be the big expense, according to all the research I've done so far."


Human Powered Transportation Projects

New in the Atomic Zombie builders gallery

Kyoto cruiser and velo

"Sociable dual velo project. Kyoto Trike rear was modified to fit into a double wide Stormy Weather shell. The Quad is just a fun thing to build in two weeks. One seat has been removed so the drive train can be seen. I have since changed to Sturmey 8 speed internal hubs as a mid drive to reduce my chain handling issues.This version of the Kyoto should fit into the Stormy shell we are building. You can see both the shell and the sociable at the Toronto bike show in March."

cargo bike

"Seat cover idea made from an old work coat." Pictures submitted by HPTA.

atomiczombie bike gallery

Friday, November 16, 2012

Build a velomobile

Four wheels – The Quadcycle

A quadcycle or “quad” is a four wheeled bike with two front steering wheels and one or more rear drive wheels. The obvious advantage of such a vehicle is stability, since it has four points on the road at all times. My initial idea was to start with a quadcycle like our StreetFighter and just bring up the seat height and overall track width a little more for visibility and stability. I had a lot of fun carving up the corners in the StreetFighter, and knew that it to be a very robust and stable vehicle for just about any kind of riding and terrain. 

But, after giving more consideration of the goals for this project, it became apparent that there would be no real advantage to having two wheels at the front and a quad configuration would make using an electric assist hub motor impossible. So, the quadcycle idea was abandoned in favor of a trike, which now left only two choices: delta or tadpole configuration.

Two wheels in front – The Tadpole Trike

A tadpole style trike places the two steering wheels in front beside the pilot and places the single drive wheel at the rear behind the pilot. This type of trike offers great handling and allows for the use of mostly standard bicycle components in the rear end and transmission system. As for aerodynamics, a tadpole trike is better than a delta trike because a teardrop body shape can be used, which places the tapered end at the rear of the vehicle for optimal travel through the air.

Another nice thing about the tadpole trike configuration is that a full fairing looks nice as it wraps around the pilot, leaving the large end in the front with plenty of room to install a full view windshield. Most of these advantages are more aligned to a vehicle designed for looks and speed, and not so much to a practical velomobile designed for everyday use and cargo carrying. A teardrop shape leaves almost no room in the rear for a cargo area, and although rear hub motors area available, they are less common and more expensive. This leaves only one other configuration to examine, the delta trike.

Two wheels in the rear – The Delta Trike

A DeltaWolf trike velo is the best design for cargo carrying.

A delta style trike placed one or more drive wheels behind the pilot and has a single front steering wheel ahead of the pilot. This type of trike offers stable handling using standard bicycle components in the steering system and a great deal of cargo carrying ability. Having the wider end placed at the rear of the vehicle means that a delta configuration is less aerodynamic than a tadpole configuration, but this is hardly noticeable at the typical riding speeds that will be seen in city traffic. For a racing vehicle designed for optimal speed, this teardrop shape is the ultimate design factor, but for a utility vehicle, it will be of little concern.

The load bearing wheels and drive system at the rear where the pilot sits are a great advantage of the delta configuration because it will offer the most traction and braking possible as well as keeping the load centered between two wheels. Since there is nothing except for the single front wheel and pilot’s feet at the front of the vehicle, the body shape can taper towards the front and keep the total volume much lower than that of a quadcycle configuration.

A delta trike is also the most robust of the three possible configurations because it uses standard bicycle components in the steering system with axles and industrial grade bearings in the rear. Having a standard set of bicycle forks in the front means that a commonly available electric hub motor kit can be easily installed to offer an electric assist drive.

So, it became obvious that a delta trike would offer the best base vehicle to use for a practical velomobile with load carrying capacity and an electric assist dive. Making the final decision on the base vehicle meant that I could now come up with my wish list of other features I wanted to have in my practical velomobile, which would include rear suspension, dual disc brakes, a suspended cargo bay, over-seat steering, long range electric drive, a trailer hitch, a head light, turn signals, rear view mirrors, and of course a full body with easy access when getting in or out. All of these features would be easy to integrate into a delta trike design.

Since winter has now set in around here and I normally work outdoors, I plan to build myself a velomobile in what would be considered reverse order – making the body first and then building the base trike to fit into the body. Typically, I’d build a body over a trike, but since I have to work indoors for the next six months and I already have a trike to use as a reference (my Aurora Delta Trike), I feel confident that this order of operations will turn out fine. The Aurora trike already has most of the features I want such as rear suspension and dual disc brakes. I only need to decide on a seat height and track width to use in the final design.

For my practical velomobile, I want a slightly higher seat height (similar to a car) for optimal visibility in traffic as well as a slightly wider track width for cornering stability and increased cargo capacity. Other than those changes, the Aurora trike is a good fit with its rear suspension, a recumbent seating position, and a robust transmission system.

I’m able to remove the rear suspension spring and simply prop up the rear of the trike to the height I want, so now I have a base vehicle that can be used to take measurements and work out the size and shape of the body. Using a few photos taken from the side, I can make several mock-ups in Photoshop to help me decide on a general shape of the body.

With a base vehicle to take measurements from and a clear set of design goals, I can concentrate on the side profile of the body, which will involve some practical thinking as well as artistic abilities. The final design will become a combination of both aesthetics and ergonomics, allowing the rider to get in and out of the vehicle easily, while maintaining a sleek modern look with pleasing curves and proportions.

Some of the other factors that will influence the final design will be the type and strength of the materials used, plus costs and complexity.

Once I decide on a final body shape, it will then be a matter of choosing the best possible materials to build a lightweight and robust body for my practical velomobile.

For the next installment of this build blog, I’ll have a decision on a final body shape as well as the materials that will be used to create it.  This project also needs an official name, but we intend to let our community choose one in the near future, so please visit our forum and offer your moniker for our practical velomobile project.

Thursday, November 15, 2012

Build a velomobile

Every time I find myself standing at the gas pump, holding down the lever while the dollars spin past, I tell myself that there must be a better way. Let’s face it, the cost of using a gas guzzler adds up to a lot more than just a dent in your wallet each time you fill ’er up, although the pain you feel at the pump is certainly instant. How about all of the effects to the environment?

Using a gas powered vehicle to pick something up from the store a few blocks away is certainly convenient, especially on a cold day when you can just press a button on your car remote starter and let the interior heat up for you. But, with millions of people doing this, what is the net cost on the environment? Call me paranoid, but with the crazy worldwide weather we have been experiencing in recent years, I think the answer is obvious. From this point forward, I will use the word “car” to refer to all gas guzzling ground transportation vehicles.

Environmental issues aside, there are many good personal reasons to be leaving the gas guzzler parked more often. My health has been impacted by the convenience of the car since the first day I passed my road test. How did I get around in the days before becoming enslaved to my car? Well, besides begging for an occasional ride, I got around on foot or by bike! 

I remember how simple things were back then. My main concerns were usually how long it would take to get from point A to B and making sure that my tires had air. I had no expensive repairs, no insurance costs, no parking problems, and didn’t have to work overtime just to pay for fuel. Ironically, I had more free time even though it took a lot longer by bike because I didn’t have to schedule in time for exercise because it came with the lifestyle! That extra body weight was a direct result of using a car, too. Sure, the car helps me get around in a hurry, but I end up either wasting more time and money to sweat over a treadmill or consulting with a doctor on how to fix my health.

Seems as though in our later years we have things backwards, don’t you think? “DING!”Oh, hold on a minute, the truck is filled now. I have to go give the attendant another $70 bucks!

I’ve decided to get a grip on my shrinking wallet and ever expanding waistline, and find a practical way to leave the car at home as much as possible. Now, the key word here is “practical”. Living in the a rural area of Northern Ontario means that I will always need a reliable car or truck to move large cargo and to travel large distances to the city in the winter, but since there are some local stores within riding distance a bike could certainly be used for many journeys.

For those who live in the city, a practical human powered vehicle with some cargo capacity could also be used for many local trips, such as grocery runs or social calls. For me, practical also means affordable and robust, which almost always translates to home built, which to us DIY types is great news. Of course, there are commercially available human powered vehicles “velomobiles” for those who can afford them, but since they tend to be as costly as a decent used car, they are out of reach for most.

All of these velomobiles pictured above are obvious works of art, but there is no way I would ever part with ten grand for something that I could build myself. Obviously, there will be tradeoffs between cost and aesthetics, but there is no reason why a very practical and sturdy velomobile could not be built using readily available parts by anyone with a few basic tools and a lot of motivation. 

In fact, I have seen some home built velos that are streamlined works of art, but often the cost of materials used and the skill set needed are beyond most of use weekend garage hackers, and the end product is more like a hotrod than a bike you would want to take out in traffic or ride around in the rain.

My goal is to build a body using basic materials that is both aesthetically pleasing yet at the same time tough enough to live in the real world. Living in the real world means taking Mother Nature’s wrath of rain, sleet, hail, wind, and constant bombardment of UV radiation. Living in the real world means surviving the odd ding, dent, or scratch from crowded urban environments, being able to bounce over a curb and take the abuse of a poorly maintained road without shaking to pieces. Living in the real world also means living in the urban jungle, so the vehicle will need to be visible in traffic and include the usual safety gear such as rear view mirrors, brake lights, head lights, turn signals and a horn. Living in the real world means offering the pilot some shelter from the elements without requiring any acrobatic maneuvers to climb in and out of the vehicle. And of course, living in the real world means that the vehicle must include some practical cargo carrying capacity for such things as groceries, a battery pack, and personal items.

So with all of these goals in mind, the first choice becomes - delta, tadpole or quad?

The type of base vehicle will determine the overall shape of the body as well as its load carrying capabilities, handling characteristics and aerodynamic advantages.  Choosing one of the three configurations was actually quite a chore as they all offered advantages and disadvantages when it came to costs, aesthetics, practicality, and ease of building. In the end, I decided that a delta trike would be the most practical base vehicle, but I will discuss all three possibilities, as well as their strengths and weaknesses.

More tomorrow

Monday, November 12, 2012

Bike builders news November 12

In this issue:

 Feature article by RadicalBrad of
Building a Velomobile - Part 1

Do you want to save money and leave the gas guzzler at home more often or for good? Do you want to learn how to build an eco efficient transportation alternative? Atomic Zombie will show you how!

This issue features our newest project, an electric assist velo for a delta trike similar to the Aurora Delta Trike. The build blog will include videos later this month. The velo build will be a regular feature in our newsletter and blogs. The brainstorming sessions have begun. Read all about it in this week's issue.


Hub flanges and axle adapters for your bike projects
Bike builders community chat
Bike builders gallery - new additions: recumbents, trikes, choppers, tall bikes, kids' bikes, cargo bikes & more 

This and archived newsletters are here.


Thanks for your feedback, and keep those suggestions coming.

  See you in the Builders Forum.