Project 100 (custom enclosed Honda C90 targets 100 mph vmax and 100 km/L FE)

[Electictracer]

Redyaris is right on in my opinion. Your vehicle should be fairly light, those brakes should be good enough. I don't think any sort of proportional mass formula would be accurate considering the longer wheel base. In my experience, It takes a lot to skid the front tire, usually the rear tire comes up first. With projects like yours and mine, we have much longer wheelbases so this will be reduced.

I think there are just to many variables (cargo weight, road surface, tire condition, speed) to try a balanced breaking system. If you got it wrong it could cost you dear. If you could get an abs system to work that is a great idea and something I have not considered. I would be interested in that myself.

Obviously the simplest answer would be just have standard controls.

[visionary]

Panic Over
I spent a couple of days thinking through design ideas for the brake system, and another day working it all out on a spreadsheet to get the bias percentage. No matter what variation I tried I couldn't get a reasonable front/rear split - but now I know why!

After some research on Brembo website I can see that using REAR master cylinders for both front and rear systems I was raising the front circuit fluid pressure higher than normal - should be 19mm(approx) for twin disc setup NOT 13mm which is std for single disc. Correct that error, but that's not the reason!
Then I read suggestions above, and whilst evaluating ideas I saw a TYPO in my spreadsheet - simply dropped a "0" from a dimension. FOOL!!
Anyway now its all good!

The bias comes out at 63% front and 37%rear which is pretty much what I had hoped for. Although the CBR twin front discs are a bit overpowering it is made up for by the very overpowering ZR750 rear piston sizes which restores the balance.

Thanks to those above for input - now I'll get on and build it up!

[HHOTDI]

anxiously waiting for updated pics...great build, keep up the good work! :{)

[Grant-53]

Each problem solved brings you one step closer! Looks like you have the the body, chassis, and brakes well in hand for 100 mph. After that you will be able increase engine output to get the acceleration you need. Years ago SAAB engineers arrived at the ideal figure of 36 lb/hp but you should be able to get along with less power using more gear ratios as do touring bicyclists. Supercharging a modified engine would be the ultimate power plant. Best wishes and ride safe.

[visionary]

Interim Update
Sorry things have been a bit quiet recently – I prefer to post news when I have something important finished or want input or ideas. Although I have been busy on the project, it seems that I haven’t had any “big” news. My goal is a test ride before Easter and road legal(ish) riding before end of April.
Here is where I am at the moment. The “pedal box” is roughly finished and mounted this image shows the layout for two pedal operation.


I’ve got to mount the fluid reservoirs but once the brake lines are made, fitted and bled that’s it for the brakes.

This shot shows the normal driving position


I had to raise the footwell height to get a comfortable pedal angle and I still feel that the available leg room is not enough.

The shot below shows the stationary “foot down” position, which is very simple to reach. The side bars are angled to make easy access for feet moving in or out. The leg angle is comfortable and the vehicle is easy to support. Note that my seat height is 500mm and the part finished bike weight is over 120kg at present.



With hindsight I would have preferred another 50mm of length to make things a bit more comfortable. Originally I set my ground clearance at 150mm, now my footwell is 70mm deep so I have 220mm footwell to ground. Even though I haven’t ridden it yet, it is obvious that 150mm is unnecessarily high, so I’m contemplating a drop to 100mm.

I’ve also been working on a fuel tank, to be located behind the seat back. The capacity looks like it will be about 18 litres and I’m fitting the standard C90 fuel level sender unit, rigged up to the temp gauge on the CBR clocks. This will give exceptional range but one downside is that calculating fuel mileage form tankfill to tankfill will take too long. In order to make quick measurements of fuel mileage during the development phase, I am going to fit a 500ml “test tank”. Actually this will be a spray gun gravity pot rigged with a ball valve so that I can run on the pot or the tank. This way I can do a 30 minute (or so) run at 100kph and get instant feedback on performance.

I’ll post pictures when the welding is finished and any other news within a couple of weeks. I have been following other threads and preparing a detailed post on my aerodynamic viewpoint, which will “put the cat among the pigeons” but that can wait a bit longer.

[Electictracer]

Cat among pigeons? Must be a UK expression. If it means what I think it does, I hope I’m not a pigeon…

[HHOTDI]

...bring it heheheheh :{)

[visionary]

Interim update and request for opinions

Although I have been making steady progress, there have been no major “breakthrough” moments as many of the larger jobs are done, and there seem to be a large number of smaller jobs which prevent me from starting a test ride.
One particular issue is that of gear selection, and I would like to invite suggestions, comments and criticisms from anyone with relevant engineering experience. Here is an outline explanation of my plans, followed by alternative solutions.
The gear mechanism is the stock Honda C90 design, normally operated by a “up and down” foot pedal. Because of its location (under the seat) this will require a “remote” means of operation. I have chosen to make this selection mechanism hand operated, and prefer that it can be operated by either hand at handlebar height.
My first choice was to use a cable operated “push/pull” system because of its light weight and simplicity of engineering. However I have reason to reconsider the design because of other systems that I am planning to use on the bike. For two other systems (leg aperture openings and parking stand deployment) I need a powered operation. My options are mechanical, electrical, hydraulic and pneumatic, so it makes sense to integrate all systems using a single technology, but which one is best?
The cable system represents my “mechanical” solution but it has no involvement with other systems.
An option using “electrical” technology would be using two solenoids (one for upshifts, one for downshifts) triggered from switches on the handlebars. This would have simplicity benefits and uses energy already available in the form of battery power. However, electrical operation of the parking stand deployment is quite difficult, so its unlikely to yield big rewards overall.
An option using “hydraulic” technology would be to employ two rams (one for upshifts, one for downshifts) triggered by solenoids controlled from handlebar switches. A single pump and reservoir system could provide power for both the leg apertures and the parking stands. Hydraulic operation of the parking stand is ideal, but has a big weight penalty using fluid and bulky motor/pump design, and I’m not confident that the fast action necessary for gear selection is easy to engineer.
An option using “pneumatic” technology would be to employ two actuators (one for upshifts, one for downshifts) triggered by solenoids controlled from handlebar switches. A simple, lightweight and cheap pump could maintain pressure in a storage tank (approx 150psi) with about 1 litre capacity (I guess). This would keep a ready source of energy for all operations and speed of gear selection should not present a problem. Drag racing bikes often use this technology, and I would be very interested to hear from anyone with first-hand experience. Actuators are lightweight and relatively cheap so it looks like a promising solution.
Let me know what you think, or if I’ve missed anything.

[redyaris]

Take a look at what shifter Karts do. they have a hand operated shifter lever. they use 125cc motorcycle engine/transmission setups and have been doing this for decades now. I wouldn't be surprised if they have tried all the methods you discribe.

[Bicycle Bob]

There is no need to harmonize your control methods. It is common to have a hydraulic brake system with a mechanical emergency brake. Clutch operation can go either way, depending on convenience.

Push-pull cables are pricy - usually the inner wire only pulls, against a return spring, so you might use two, or a detent arrangement balanced against the Honda parts.

As to the high actuating force for the stand, I recommend a two-part action. Assuming a lever to deploy the wheels, the first half of the motion releases the landing gear, and gets it onto the ground by gravity or by spring action. The second half of the stroke applies an over-center clamp to hold the gear on whatever slope it has found the ground at, while the spring, if used, keeps stretching harmlessly. Both actions can be low-force at the handle, quick, and easily reversible.
I'd stick with all-mechanical. Cheap cables are certainly adequate for far finer adjustments to derailleur gear systems.