[The Toecutter]

Originally Posted by Bicycle Bob

I like it, but I'd like it more with integrated frame and suspension. Why build something rigid when flexible is lighter and more functional? It could be done in steel, but you'd have to really enjoy advanced metalwork.

I like things to be repairable/replaceable at the component level if need be. I do not want a suspension integrated into the frame because if the suspension fails or I get into a minor accident, I'd like the odds to be likely that I can repair it with standard parts, and not have to replace the entire vehicle.

1g lateral sounds wonderful for conserving momentum, but in the real world, you seldom get to use it without bothering people.

I'm considering this from both a performance and safety standpoint.

To stay narrow for filtering and passing man-doors, I'm seriously tempted by the complications of a tilting mechanism.

Tilting mechanisms are very difficult to get working. I'm going to avoid bothering with that for the near-term future. It's also another part to fail. This can be made up for with proper design of chassis geometry, sufficient wheelbase and width, at the expense of turning radius and overall agility.

In any case, I think that .6 g is sufficient.

Certainly. Most trikes/velomobiles will tip at around 0.5G, but they are also much more narrow than 40".

You get much less rolling resistance with relaxed traction demands, too.

If the tires are the limiting factor regarding traction, the vehicle will skid instead of tip, in most cases. So having a tipping point of 1G while the tires can handle up to 0.85G before skidding would still be great. LRR tires with poor traction in cornering would basically mean the vehicle was tip-proof in normal operating conditions, which is highly desirable.

I would also recommend paying serious attention to directional stability. With such a light, fast, streamlined form, traction becomes unreliable. Aim to have a stable glider fuselage that usually stays on the ground, but does not yaw in a crosswind gust, even on wet ice. It just moves over.

All agreed. Downforce will certainly be a consideration here as well. The tail will have to taper to a fine point, and the sides will have to be designed to break up crosswinds. Center of gravity will also have to be as close as possible to the center of pressure, preferably with both slightly behind the front wheel axle line.

I just took my current build out for another 15 mile ride today. It is stable going 40+ mph downhill with side gusts of 15+ mph. I barely notice side winds impacting my directional stability at all, and the body shell acts as an excellent sail for any side/tail winds the way I designed it.

I'm looking forward to fairing the front wheels! That will be the next large gain in efficiency to be had.

Everything I've learned with this design is going to be transferred to a custom car. The concept of a 1,000+ MPGe electric car that can accelerate like a high end motorcycle is just too alluring, as is a velomobile variant that can move like a car and still be pedaled like a bike with everything shut off. One could literally go for tens of miles on just one cent of electricity in either of such a thing. Part of the reason I developed an affinity for bicycles was their simplicity and low cost of operation,in addition to their fun factor. Whatever cars I design are going to reflect those attributes as a design philosophy.