May 3

May 3, 2004

Sweet!

OK - this is it. I adjusted the angles of the pulleys so that they were all perfectly lined up and then greased them. Then I refabricated the steering levers. I took a sealed bearing out of an old front hub and welded it to a 3/16 inch steel flat bar (note: Welding sealed hubs isn't a very good idea because the grease evaporates). Then I welded on two handle bar grips from a kids bike. The lever action is super smooth thanks to the bearings, but the steel plate is not stiff enough - good enough for this proof of concept monster, but too flexy for anything permanent. I think using an aero shaped, narrow front fork would probably work better. The reason for the change from the round tubing that I had before is because my knees kept smashing into them. This is much narrower and works great!

Upon some sound advice from my technical guru, John Mackay, I 'closed' the loop by adding a pulley to the front of the levers. Now, when I pull the right lever back to initiate a right turn, the left lever is pushed forward. The action is really cool. To turn left, you both pull back on the left lever and push forward on the right - something like a standard steering bar.

I also got rid of the springs - once this bike is moving, the trail does a pretty decent job of keeping it centered and upright. Now that I have more leverage on the steering handles, and a nice, tight cable fit with the 'closed-loop pulley', it's really easy to keep the bike upright when sitting still.

I also moved the rear wheels back a few inches to match where they would have to be on the next version which hopefully will be very close to the final vehicle design. As you can see by the drawing below, the rear wheels are directly below the rear pivot.

The blue lines show how the steering cables are routed.

Now, the only thing I am still not absolutely sure about is the large front drive wheel and knee interference with the gear cluster and/or the derailleur. I'm very concerned about this because if there is an issue, the only way around it will be to go with a smaller front wheel which I do NOT want to do due to gearing issues (larger wheels have lower rolling resistance as well as higher gear ratios), or move the bottom bracket (cranks) up higher which will totally destroy the aerodynamic advantage of the low, laminar fairing.

Still need a name - any ideas???

TransCanada1, XCanada1, TransCanadaRocket ??


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