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Old 11-16-08, 11:17 AM   #1
RLSchell
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Electrec sound on hard acceleration

I fully realize that ebikes should probably be pedaled a bit from a dead stop before engaging the motor, otherwise the torque places a lot of strain on components. However, sometimes my thumb is quicker on the throttle than my feet are on the pedals, particularly at busy intersections. When this happens under load (e.g., uphill from a red light), my Electrec makes a brief, loud clunk/sproing (perhaps pop/sproing) sound from the rear. It sounds sort like the drive chain skipped teeth on a sprocket, though the close engagement of the chain makes that appear unlikely. Anyone else with an Electrec also get this noise sometimes? Any idea what it is and if I'm doing any damage when it happens? It's happened many times and there's no obvious damage. I can't reproduce the effect except on road, under load, up hill. I make sure the motor mount bolts are tight and the motor drive chain is fully engaged on the sprockets. I've had the rear wheel off a couple of times to change tires and I try to make sure everything is aligned and centered (not easy on the Electrec, changing the rear tire can take a few hours!), yet the problem persists. Naturally, I could avoid this by better training myself to pedal more before hitting the throttle, but I'd still like to know what's making that noise. Ideas?
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Old 11-17-08, 10:31 AM   #2
npkeith
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My electrec was doing that a lot after a tire change. It turns out the bike shop had removed the motor. When they put it back on, it was too loose. My guess is the chain has stretched and is just a *little* too loose. The motor chain should have 1/8 to 1/4 of an inch deflection when you push on it. You might try loosening the bolts that hold the motor, and gently tapping the motor back a fraction of an inch or so to tighten things up.

(per the guy at Electik Motion who's name escapes me, its better to be too loose than too tight (puts strain on the motor axle), but not so loose it skips - shift the motor just enough to stop the skipping.)
-Keith
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Old 11-17-08, 03:05 PM   #3
RLSchell
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Sounds like my problem. This didn't start until after I had removed the rear wheel for first time. It is slightly easier to get the wheel off and on if you remove the motor, but it's not easy either way. I have re-tensioned the motor in the mount several times over the last few months. Every time I do this, the problem SEEMS goes away for a few days and then comes back. Hard to say for sure because it doesn't happen every day. I'll tension the chain and really tighten down those mount screws. Thanks for your help!

BTW - I'm starting to get the throttle issue you mentioned in another post. My fault because I jammed test leads into the connector to check the throttle pot. resistance and now the connector doesn't grip the pins as tightly. Looks like I have a couple of projects for this evening...
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