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  1. M

    Broken Spoke. Am I fat or do spokes age??

    Most spokes failures are due to stress at the elbow caused by unloading when the tire in the vicinity of the spoke pushes against the ground or an obstacle (e.g. pothole). Spoke nipples can loosen if the spoke becomes slack, effectively loosening the rest of the wheel and increasing the...
  2. M

    Pikes Peak Race--Entering?

    Rats, I've been found out. Luckily, I possess l33t sk1llz and have already planted posts in this very forum, retroactively making it look like I announced the conspiracy, er, I mean support for Josh, last Wednesday. But it goes deeper than that. Are you ready to take the red pill, my friend...
  3. M

    Pikes Peak Race--Entering?

    To each his own. I think swapping packs is just dandy as long as you carry the spare along with you. At least one ebike last year swapped packs somewhere close to the top. I don't know about the Optibikes. The organizers have made it clear that motor vehicles are not allowed on the course...
  4. M

    Pikes Peak Race--Entering?

    It would be funnier if it were true. I can't speak for all Optibike owners, but those of us who participate in the Google group are genuinely enthusiastic about all sorts of ebike developments. One of us (me) is even sponsoring a competing bike using Ron Rocha's chain puller drive. I'm...
  5. M

    Pikes Peak Race--Entering?

    Are you suggesting that showing up to this USA Cycling sanctioned Fun Ride with the 6000W motorcycle-with-pedals mr greenwhatever was foaming at the mouth about is in good taste? You seem to have trouble understanding that this is a bicycle ride, and that motor vehicles are specifically prohibited.
  6. M

    Pikes Peak Race--Entering?

    Thanks for a helpful and informative response :roll: Perhaps you can provide something more concrete? Are you disputing the fact that engines run hot when the mixture is leaned from optimal? Perhaps you believe humid air is a better conductor of heat? I'm willing to discuss this so we can...
  7. M

    Pikes Peak Race--Entering?

    http://www.google.com/search?hl=en&q=why+does+a+lean+engine+run+hot I'm not an internal combustion engine engineer and don't have a complete understanding of the reasons for the phenomenon. I can tell you it is plainly evident when tuning model airplane engines, and is widely reported elsewhere.
  8. M

    Pikes Peak Race--Entering?

    I don't think so. The specific heat of dry air and water are roughly 1.01 and 1.86 kJ/kg.K, respectively, depending on conditions. However at standard conditions 100% humid air is only 3% water vapor, and has a specific heat of 1.01*.97+1.86*.03 = 1.035, a mere 2.5% increase (up to 6% increase...
  9. M

    Pikes Peak Race--Entering?

    That does not make sense. A BLDC motor's Km constant is independent of winding. In other words resistive losses are a function of torque, not turns. Iron losses (eddy currents) depend only on n*I (turns times current) - they are determined by torque (and speed) and are likewise independent of...
  10. M

    Pikes Peak Race--Entering?

    Eric, you truly are an idiot. No, I do not work for Optibike. Thanks for the laugh. Unfortunately you are, overall, far more annoying than funny. Still I figure one more post here to set the record straight is justified despite the adage "please don't feed the trolls". Regardig your battery...
  11. M

    Pikes Peak Race--Entering?

    Obviously you don't know what I ride, nor much else about me. Calling me a hypocrite was an act of ignorance. You owe me an apology. Gotta love them conspiracy theories. In the real world, where I ride, Jim and Kyle ran stock Optibikes last year. I assume they plan the same this year. The...
  12. M

    Pikes Peak Race--Entering?

    Check your facts, my friend. I run a small (44 tooth) chainwheel on my Optibike for insane climbing, but it limits my top speed (without pedaling) to a road legal 20mph. The power is also legal: 800W * 85% efficiency (estimated) = 680W, safely below Colordo's 750 W limit. It rides like a...
  13. M

    Pikes Peak Race--Entering?

    You completely miss the point. This is a private bicycle ride. The course is "closed to motor vehicle traffic". If you bring a sufficiently powerful electric-motorcycle-with-pedals, someone is bound to complain and there will be consequences. The police can issue a ticket for riding a non-street...
  14. M

    Wheel Building!!

    Oil on the threads only allows the nipples to unscrew if the spokes lose tension! Otherwise, friction (particularly nipple against rim) prevents them from unscrewing. Again, slack spokes are bad wheel juju, but if you are worried about it use some spoke prep (or linseed oil) which lock the...
  15. M

    Wheel Building!!

    I have only built wheels with 14 or 15 gauge (preferably butted) spokes with 56 tpi threads, so I can't speak from experience here, but with fewer threads per inch, a thicker spoke should have a similar thread ramp angle, allowing you to reach the same tension. You can check spoke tension with...
  16. M

    Wheel Building!!

    Thinner spokes (higher gauge numbers) stretch more, which good because they lose less tension at the bottom of the wheel than thicker spokes. Maintaining tension prevents the nipple from loosening (and unscrewing) and reduces flexing at the elbow where the spoke goes through the hub. I'm not...
  17. M

    wich relationship is between Vp and Vrms?

    My oscillogram (the second one) was taken across the leads of an old brushless model airplane motor (Jeti Phasor 30-3). You see negative values for two reasons: First, the voltage is the relative difference between two of the motor leads. The controller switches these from positive to ground...
  18. M

    wich relationship is between Vp and Vrms?

    That's a surprisingly clean signal - I'm used to working with RC motors (also BLDC) with signals like those shown in the image below. Part of the difference is the motor timing (my controller is only supplying power during a portion of each 1/6 of a cycle), but I don't fully understand the...
  19. M

    wich relationship is between Vp and Vrms?

    It might help if you tell us why more about your interest in peak and RMS voltages. For most practical purposes, you can think of a motor controller as supplying a constant voltage, equal to the battery voltage multiplied by the duty cycle of the high frequency PWM waveform. To model...
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