eBike Wheel Resistance too High

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  #1  
Old 07-07-19, 09:36 AM
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Unhappy eBike Wheel Resistance too High

I have a Yukon Navigator SF24 electric bike that moves up to about 20m/h. But when trying to paddle manually, it's very difficult. I know it should have some resistance due to the strong magnets, but the resistance seems far too high. Lifting a bike and trying to turn the wheel by hand takes large amount of force, and it stops immediately as soon as I release it.

I have not been able to find any service manual for this bike, and neither Sears nor Webzenia was helpful. Is there an adjustment to reduce the resistance? Thanks.
 
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  #2  
Old 07-07-19, 10:31 AM
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Here is the manual I found online.

First I would rule out possible mechanical problems like the brake dragging.

What controls do you have for the motor? The manual lists several different possibilities. Any possible way you have changed modes and engaged dynamic or regenerative braking?

Then I'd try contacting the bike manufacturer. Hopefully they have instructions for the Chinese drive system.

After that I would start searching for electric bike drive systems for a manual. Almost all those drive systems are imported from China so I don't think you'll find any reference to your brand bike. You'll just look for "some" instructions and really hope that there is anything you can do. I assume anything will require plugging your drive system into a programming module or computer. Somehow the firmware might have gotten corrupted turning on dynamic/regenerative braking or something similar. This mode can be used to charge the battery like when coasting down a hill. Unfortunately it can also mean that when pedaling you are also trying to charge the battery greatly increasing the pedaling effort.
 
  #3  
Old 07-07-19, 03:38 PM
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if you disconnect the battery and wait 20 minutes is it still hard to turn? if so would look at mechanical issues like brake or even bearing ,if its much easier to turn perhaps its a motor controller issue
 
  #4  
Old 07-07-19, 04:28 PM
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Does the wheel spin freely if you lift it off the ground and spin it by hand? And there's no sign of a rear brake in your photos but I presume there is one. Are you certain it isn't binding?
 
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Old 07-08-19, 08:21 AM
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Thanks for all the replies.

@Pilot Dane: I do have that Operator's Manual. Only control this bike has is the key to turn it on, and the throttle grip to accelerate, and the brake level to activate the brake hub. There is no other, to change mode or any. I have sent email to mfg, but no reply yet. I haven't, yet, but will try searching for the manual to the motor.

@alan73: I remove the battery entirely, completely loosen the brake, but still same.

@Fred_C_Dobbs: No it doesn't spin freely. In the photo, the wire with the spring on it is the brake wire, attached to the level that activates the brake in the brake hub.
 
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Old 07-08-19, 08:25 AM
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itchibahn:
[email protected]_C_Dobbs: No it doesn't spin freely. In the photo, the wire with the spring on it is the brake wire, attached to the level that activates the brake in the brake hub.
Well, obliviously I wasn't looking very closely, was I?
 
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Old 07-08-19, 08:51 AM
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Just for curiosity, I started to push/pull anything that can be done, and although it still has great resistance to initiate the spin, it now will spins freely one cycle before stopping with high resistance.

In the following photo, I've completely loosen the screw (marked by the red arrow). This allows the wheel to spin freely one cycle before stopping. The resistance seems to increase as it's screwed in. Not sure how this work because there's only that cylinder which seem stationary (doesn't move), and all the screw does is putting pressure on it.

At least, it's better than before, but still need to lessen the resistance. I may have to disassemble the brake hub to see what else can be done.
 
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Old 07-08-19, 10:09 AM
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It looks like you are assembling a brand new bike. Have you contacted the supplier/manufacturer? What do the instructions say?

It appears the brake is not properly installed over the drum. It looks crooked. That could be causing the brake to bind or drag.
 
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Old 07-09-19, 12:22 PM
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@Pilot Dane: I also thought that brake cover was installed incorrectly, but after carefully measuring the width, that cover is actually narrower on that side.

The bike came with rear wheel already installed. Only thing detached was the front wheel, handlebar, paddles, and seat.

So far no response from the mfg. I'm going to remove the rear wheel to see if that brake cover could be removed. For now, I'm painting and re-flooring one of my bedroom, so it's gonna be a week before I can get to it.

Thanks.
 
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