Monday, November 30, 2009

What Features I want in a potential streamliner and why?

Practical Streamliner 03
Recently I have been considering streamliners as commuting platforms. The so-called "practical streamliner" bike problem. This is an interesting problem to be solved.

Commercially there are a few approaches that have been taken.
  1. The Velomobile, a tadpole trike platform with a shell. Examples include the Quest, the Go-One, the Sorcerer, etc. Most are heavy (~70lbs) and the tadpole format adds a certain about of tire scrub and rolling resistance. Even so, this is the format that is the most common for practical applications today. It is also very fast as long as you don't have too many hills.
  2. Fabric and wireframe Faired bikes, the Lightning F-40, which holds the fasted time ever in RAAM is the classic example. Faired Easy Racer Gold Rushes are another common example and the lowracer above with a customer carbon fiber front fairing and cover is within reach. These tend to be lighter, in the 30-40lbs range and the cost is lower. The speeds are good, especially since the weight is low and low weight means that climbing is not as affected.
  3. Hardshell streamliners, tub bikes, these are the real speed bikes, also about ~70lbs with limited steering radius and other practical limitations. These tend to be individually produced with custom design features. There are examples that have been made more practical and can be used in general traffic and riding applications. Joe's streamliner built around a varna clone shell is one example

The question is what makes a good platform to build a streamliner around. You want a number of components.
  1. Suspension, a streamliner is faster and due to the opaque body generally has reduced forward visibility for road bumps and hazards. You will hit bumps fast and you want to be able to handle it. Suspension also helps stick to turns better at speed. Most streamliners can easily average in the mid 20s MPH or low 30s MPH if the road is reasonably flat or rolling hills. Suspension helps make this comfortable and keeps the tires on the road.
  2. Large Gear Range, a streamliner wants high gears to avoid spinning out in the 25-30mph range. It also wants low gears to climb hills with the extra weight. A gear range from 17 GI to 120GI is adequate for most practical applications. This can be accomplished with a jackdrive (intermediate drive), an internal hub, or something like the SRAM dual drive.
  3. Indirect Steering, indirect steering or some other method to control how much your steering apparatus goes to the side during turns. Traditional Tiller and U bar steering can take up quite a bit of width during turns, widening your profile and reducing the aero benefits of the streamlining. Indirect steering can eliminate this entirely though it does add complexity. Other solutions are sitting very close the the fork and putting a small T bar steering directly on top of it.
  4. Entry, Exit and Stoplight solutions, a trike of some sort makes a good practical streamliner since entry, exit and stopping/starting are all pretty simple as long as you can get in and out of the fairing. Bike solutions have to worry about bomb-bay doors for the feet, clearance for derailleurs , etc. The inherent stability of trikes helps a lot for low speed handling like climbing. Most of the practical 2 wheel streamliners have either open bottoms or do something with bomb bay doors (complex) or fabric (simple) to improve the aerodynamics on the underside. Entry and exit is also very tricky with a 2-wheel streamliner. The F-40 and other fabric/nosecone solutions solve this reasonable well. Many 2 wheel hardshell solutions require helpers to launch/catch them. This is not very practical.
  5. Storage, some form of storage and luggage capacity. A streamliner is useful for both speed and weather protection. You will want to carry the odd bit of groceries, a change of clothes or maybe a laptop. 20 -to 40L of storage is a nice thing to have. The extended tail section of most streamliners does provide a location that suits many designs. Even a way to add a small basket back there provides useful storage.

Looking at this list, you can see why tadpole trikes do well as velomobiles. I am looking for a bit more speed and less tire scrub so I am considering a tilting trike as a platform. Though a lowracer modification such as the one pictured above is also highly tempting. I suspect I could invest $1000 or so into such a solution and come up with something workable.

Sunday, November 29, 2009

Posting Schedule and random news

From RandomPictures

I haven't been posting much lately. Mostly due to the new house and because work has changed lately requiring more hours but also due to the fact that it is the winter. I will continue to run this blog and will post interesting items. For instance Arnold of Raptobike is planning a FWD trike design and has reserved the name I am hoping for a tilting trike out of this.

With the winter and my longer commute I find myself wishing for a trike to commute with. Especially a trike with a fairing, aka a velomobile. In the US, Bent Up Cycles has become the premium velomobile dealer. Dana carries the bluevelo Team, the Greenspeed Glyde and seems likely to start carrying the Quest version produced by Bluevelo under license from Velomobiel. Dana imports VK2s from Poland and carries a number of other European brands. If a tilting trike comes to the US my money says Dana will carry it, especially if there is a velomobile version.

At least that is my hope since I don't want to ever get a second car and prefer to find a car alternative in a velomobile. I don't think I will need the large carrying capacity of the quest. If I can carry groceries for dinner and a gallon of milk then it will be enough for me. My mostly likely day to day cargo is the commuting load. A laptop, a change of clothes, tools and a jacket. With this in mind I want a lighter weight velo and a narrower track. This leads me down the narrow wheelbase of a tilting delta trike framework. I see enough room for the basics in a turtledeck behind the seat and the tilting delta format is good for stability even in the wet leaves I sometimes traverse. Something like the Munzo TT would be nearly ideal with the indirect steering and the take apart frame for transport.

I think a functional, fast, velomobile would be nearly ideal 3/4s of the year and my raptobike would be my summer bike. I could outfit it for fun, lightweight, road cycling and keep the velomobile platform setup for commuting and foul weather. I would love to try this. If I have to make my own shell I will need to experiment with a tailbox for the raptobike first. Cleaning the garage of all the crap from the move becomes a priority then. Ah well, back to the reasons why I am not posting as much, too busy. I will continue to post but not quite as much as I had been.

Monday, November 9, 2009

Still Commuting

The Puget Sound rainy season has started. I am still cycle commuting, even in the rain but I have wimped out a few times. I added more lights to my helmet which gives me a bit of control over where my light goes and allows me to turn the lights on or off while in motion. It also lights up my cockpit controls without having to turn on the backlight for the gps or bike computer.
Raptobike 002

Lately I have been wondering what it would take for me to have a foul weather bike without sacrificing too much performance. The Munzo TT trike caught my eye. A 40cm track width, tilting delta trike with indirect steering and suspension. It is a very good platform to put into a homebuilt shell and the guys at seem to be planning to make it into a velomobile as well.

Here is the video of the trike in action:

Tilting trikes don't experience the same tire scrub that a normal trike does in turns. Delta trikes are also faster than tadpole trikes though normally aren't as stable in turns. The tilting changes that equation and makes the trike even better in turns than a tadpole. The narrow track width means a shell will be narrow as well. Suspension is always a good idea for a streamliner since you will hit bumps at speed. Disk brakes are also a good idea and this trike has the mounts for them. Additionally the Munzo TT separates which makes transport much easier. If the shell also separates (as it should) then you can transport the contraption pretty easily. Overall a very exciting idea and one sure to occupy my thoughts this winter.