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  1. J

    120% speed advanced timing on the controller programming

    From my slot car racing days (looong ago), retarding the timing has the opposite effect - it sacrifices RPM for more torque. How you wired the car's motor depended on whether you were more interested in drag racing (torque) or long track races (RPM). Of course there are limits to what...
  2. J

    Speed sensors?

    Filzer sells them as a kit. E.g. - http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442629081&FOLDER%3C%3Efolder_id=2534374302693003&bmUID=1249923929625 (that link is to a co-op, so you can't buy without becoming a member; it was the only example I could think of). Any...
  3. J

    BIMOTO MODIFIED Free Wheeling CRANK MECHANISM

    No, I think your postings start to look more like spam than information. One good post is all you need.
  4. J

    BIMOTO MODIFIED Free Wheeling CRANK MECHANISM

    Did you really need to post the same information in three threads?
  5. J

    Clever "Contortionist" Folding Bike Design - pics and vid

    Flexible drive shaft?? Curved to fit inside the "chain stay."
  6. J

    How much more power?

    As long as you keep in mind that heat and temp are different things, you'll be fine using that concept. WInd flow will keep the heat down without reducing the temp below ambient. However, don't use the wind chill charts to estimate what will happen with a motor. Those charts are calibrated...
  7. J

    What one-off bike should I build to sell?

    Better late than never: http://gizmodo.com/5322478/tron-legacy-trailer-officially-released Tadpole with a difference. I'm sure this would sell.
  8. J

    Chinese Products: Buy at your own risk

    "Made in Japan" used to mean crap, then the Japanese made better and better products. South Korean cars were crap at first (remember the Pony?) and other SK products like home appliances were mediocre. Now they are as good as that from any other country (comparing comparable prices ranges, of...
  9. J

    this is kinda an odd question

    Since when are bicycle parts supposed to handle motor loads? You should be more realistic in your expectations.
  10. J

    Japanese ebike pics

    A chain tensioner so that you don't have to fiddle with rear wheel position for chain tension. Not required if the bike had a rear derailleur instead of a gearless or internally geared hub.
  11. J

    My belt broke - motor's timing pulley isn't secure

    For checking the alignment of the drill press table, get a small engineer's square engineer's square http://www.leevalley.com/wood/page.aspx?c=1&p=32601&cat=1,42936 (they are generally available from many places that sell good wood or metal shop equipment). Use it to confirm that the drill bit...
  12. J

    How much more power?

    FWIW, I've seen a bunch of larger motors, including EV motors, that are liquid cooled. The liquid jacket is built into the motor housing. Add a radiator and pump and you'll start looking more like a modern motorcycle. :)
  13. J

    Bicycle helmets wind noise?

    Another possible solution is to simply twist the strap. Flat straps will flap in the wind, while twisted straps will shed air differently and the sound is quieter; if you're lucky it might be less annoying. Putting a twist in a strap is a standard technique for reducing wind noise in roof rack...
  14. J

    My belt broke - motor's timing pulley isn't secure

    So if you don't have the manufacturer's rated torque constant or Kv, you'd have to run a test to measure the Kv by fiddling the V and counting the rpm each time. Calculate the ratios (plural - one data point does not a good measurement make) and see that you get a reasonably consistent value...
  15. J

    Bicycle helmets wind noise?

    My comment is about protection in an accident, not about noise. If you value your noggin, you should use a helmet that matches the conditions of use. BTW - the most common bike accidents requiring medical attention result from cyclists hitting stationary objects (more than half of all...
  16. J

    My belt broke - motor's timing pulley isn't secure

    When I saw this, two things stuck in my mind: 1 - How come after all these years, I've never seen this equation? 2 - Why is my gut feeling saying "This is wrong"? I'm a CE from way back (specialty is structures, hence forces, stresses, dynamics etc). Not being a ME means I may have missed...
  17. J

    My belt broke - motor's timing pulley isn't secure

    Dudes - the torque is due to the two forces (shear at the pin where it exits the shaft's hole at two diametrically opposite points) separated by 8mm. Hence the calculation is either twice 4mm times one of the shear forces or once times 8mm times one force. 8mm is correct.
  18. J

    My belt broke - motor's timing pulley isn't secure

    It shouldn't be 150lb. That assumes static loading. With dynamic loading, the exact load will be dependent on the nature of the loading characteristics (sinusoid, sawtooth, square etc). A factor of 2 is a back-of-the-envelope guesstimate that is often used. Hence that would halve the ratio...
  19. J

    Bicycle helmets wind noise?

    At those speeds, a bike helmet is likely a bit too light for protection. You really should be looking at a motorcycle helmet anyway.
  20. J

    GPS for bicycle use

    Some of the "automobile" GPS navigation units have features for pedestrians too. This means they may have shortcuts that cyclists can use. They aren't sold just for cars but as general purpose nav devices. Look at the full feature set before buying. Note that if you live in a significant big...
  21. J

    2 Girls + 1 Tandem + ebike kit suggestions

    I wonder if a pair of geared hub motors like Ezee, both front and rear, would provide the torque required without the weight of the 5xxx motors?
  22. J

    Gates Poly-Chain

    That's a minor change - they just "cut through" the rear dropout and bolt it closed. Personally, for all the cost and bother, I'd just as soon go for a shaft drive. They have all the advantages of a belt with less chance of breakage. The best shaft drives are negligibly less efficient than...
  23. J

    My belt broke - motor's timing pulley isn't secure

    Where do you get the 15:1 safety factor? Where did you get the 3-4 ft-lb torque?
  24. J

    2 Girls + 1 Tandem + ebike kit suggestions

    That's not a problem with Hall sensors, that's a problem with bad design. If the Hall sensors were properly waterproofed, this wouldn't happen.
  25. J

    My belt broke - motor's timing pulley isn't secure

    Don't forget that when you compare 150 lb resistance to 250 lb limit, you are not taking into account a safety factor. Also, the loading can be dynamic, not static, so the actual load might be double that 150 lb estimate - now you're at 300 compared to 250. Still without a safety factor, BTW...
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