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Dakoroman Drive System Pdfx1
rob.northcott wrote: You're effectively using the rider's ankle as the torque arm of the gear system, right, even if the pedal was firmly attached to the shoe? Also, the pedals would move in a freaky way round the circle unless the rider kept their feet at the same angle for the whole revolution (which they don't) - a bit like PowerCranks as somebody else mentioned. That may make unicycling feel pretty bizarre, but might not be a problem. Ioan- I agree with Rob that this would add some very strange feel to the pedaling motion. The pedals are going to want to rock back and forth while riding. Our pedals don't stay flat throughout the entire revolution of the cranks. In your system as the rider rocks the pedals the cranks must rotate slightly about the wheel axle. In fact, for the 2:1 system for every 2 degrees of pedal tilt the crank will rotate 1 degree about the axle. For 150mm (6") cranks this constitutes 2.5mm (0.1") travel at the pedal. One of the disturbing things about riding a geared unicycle (as many now know) is the backlash felt at the pedals. In my design I had to accept 0.5-1.0mm of variation at the end of a 150mm crank due to inherent gear backlash. I knew this ahead of time and wondered how difficult it would be to adjust to. I think it must be about the same for Florian's hubs. In your geared crank design, for just 2 degrees of pedal tilt throughout the crank revolution this is already 2.5 to 5 times as great as the gear backlash of an epicyclic hub and would be perceived the same way. I have not included the backlash already present in the crank gears but that would be a cumulative effect. The "long pedals" are required to permit the body to exert a force with the heel to counteract the tendency of the pedals to rotate around with the cranks. This is useful only while applying pedaling torque. On a unicycle the rider must constantly adjust the applied torque to maintain balance in the forward/backwards axis. When the torque is suddenly reduced on a unicycle to correct and balance, the toe rather than the heel would be required to maintain the pedal in a horizontal position. Because of the short lever arm on the front of the pedal, it would rather easily try to rotate under the foot right at the very moment that the rider attempts to correct his balance. This would be unnerving to say the least. You have made several references in your posts to small wheels, of order 12" in diameter. Small wheels do not fare well over rough surfaces, especially at high speeds. The small wheel size amplifies road irregularities. These irregularities need to be corrected by the rider by varying torque at the wheel axle. This takes physical energy and concentration. The portability of a small wheel becomes moot if the vehicle is not ridable. I would recommend that you not suggest using small diameter wheels on a unicycle driven by your gearing scheme. Long distance unicycle riders use large diameter wheels for a reason that it quite obvious to unicyclists but not so apparent to those who do not ride. Can you make some comments about these issues? Maybe you already have some design refinements in mind. Again, these may not be significant issues for other pedaled vehicles but for unicycles they certainly are. -- harper -Greg Harper *jc is the only main man. there can be no other.* "In general, I'd like everyone to just stop treating one another like crap. I see it every day. It sucks." - SqueakyOnion ------------------------------------------------------------------------ harper's Profile: http://www.unicyclist.com/profile/426 View this thread: http://www.unicyclist.com/thread/70516 Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- http://www.usenet.com |
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