Comments on: Stokemonkey safety notice http://clevercycles.com/2006/11/13/stokemonkey-safety-notice/ Thu, 02 Sep 2010 16:54:08 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Clever Cycles » Blog Archive » Stokemonkey sales & marketing pause http://clevercycles.com/2006/11/13/stokemonkey-safety-notice/comment-page-1/#comment-51448 Clever Cycles » Blog Archive » Stokemonkey sales & marketing pause Mon, 11 Jun 2007 18:18:33 +0000 http://todd.cleverchimp.com/blog/?p=161#comment-51448 [...] last year we identified a safety liability with Stokemonkey. We have since tested several potential fixes, and rejected most as unreliable. [...] [...] last year we identified a safety liability with Stokemonkey. We have since tested several potential fixes, and rejected most as unreliable. [...]

]]> By: Todd http://clevercycles.com/2006/11/13/stokemonkey-safety-notice/comment-page-1/#comment-15246 Todd Mon, 13 Nov 2006 23:51:58 +0000 http://todd.cleverchimp.com/blog/?p=161#comment-15246 Allan, if you're riding the bike when the problem occurs, just applying the brakes in whatever gear you're in and turning off will take care of things -- the controller will "give up" stutteringly if the motor can't advance at all. If you go to a low gear, you'll just need to apply the brakes harder to overcome the greater torque; conversely, going to the highest gear will load the motor hardest, making it easiest to brake. The case I worry about most is when you're not on the bike with your hands near the brakes at all, but standing aside it as you power up. Let's say you have a kid strapped in as you do this... small risk, unacceptable potential consequences. For the curious, the problem occurs when the wire or contact corresponding to the middle of the three-pin throttle connector is interrupted, with the other two intact. The fix will involve a throttle fault detection circuit in the controller that cuts power when the throttle signal is outside normal operating parameters. There are many other parties distributing substantially the same subcomponents in other electric bike products. I had heard of runaway throttles, but in previous cases believed it to be related only to throttles with an LED power indicator -- seems the indicator signal has a tendency to leak into the control circuit, especially in wet conditions. Stokemonkey hasn't used these types of throttles for this reason. But now we understand that it's a more general problem that needs a more general failsafe strategy to address. I think Cleverchimp is the only one publicizing the problem and pressing a fix because the other products tend not to be sold as suitable for carrying passengers; any passenger/cargo space on regular electric bikes tends to get taken over by batteries. Allan, if you’re riding the bike when the problem occurs, just applying the brakes in whatever gear you’re in and turning off will take care of things — the controller will “give up” stutteringly if the motor can’t advance at all. If you go to a low gear, you’ll just need to apply the brakes harder to overcome the greater torque; conversely, going to the highest gear will load the motor hardest, making it easiest to brake. The case I worry about most is when you’re not on the bike with your hands near the brakes at all, but standing aside it as you power up. Let’s say you have a kid strapped in as you do this… small risk, unacceptable potential consequences.

For the curious, the problem occurs when the wire or contact corresponding to the middle of the three-pin throttle connector is interrupted, with the other two intact. The fix will involve a throttle fault detection circuit in the controller that cuts power when the throttle signal is outside normal operating parameters.

There are many other parties distributing substantially the same subcomponents in other electric bike products. I had heard of runaway throttles, but in previous cases believed it to be related only to throttles with an LED power indicator — seems the indicator signal has a tendency to leak into the control circuit, especially in wet conditions. Stokemonkey hasn’t used these types of throttles for this reason. But now we understand that it’s a more general problem that needs a more general failsafe strategy to address. I think Cleverchimp is the only one publicizing the problem and pressing a fix because the other products tend not to be sold as suitable for carrying passengers; any passenger/cargo space on regular electric bikes tends to get taken over by batteries.

]]> By: Allan F http://clevercycles.com/2006/11/13/stokemonkey-safety-notice/comment-page-1/#comment-15243 Allan F Mon, 13 Nov 2006 23:20:35 +0000 http://todd.cleverchimp.com/blog/?p=161#comment-15243 Hmm, so would it be better to downshift into the granny gear, almost immediately slowing the bike down, or up shift to the tallest gear to take away as much mechanical advantage as possible, and let the brakes do their thing? I'm guessing what's best may depend slightly on the situation. But the very quick drop to the granny gear, maybe even derailing the chain in the process, seems a natural panic maneuver. On the other hand, lugging the motor and relying on good brakes seems a pretty effective course of action. Hmm, so would it be better to downshift into the granny gear, almost immediately slowing the bike down, or up shift to the tallest gear to take away as much mechanical advantage as possible, and let the brakes do their thing?

I’m guessing what’s best may depend slightly on the situation. But the very quick drop to the granny gear, maybe even derailing the chain in the process, seems a natural panic maneuver. On the other hand, lugging the motor and relying on good brakes seems a pretty effective course of action.

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