Wheel difficult to turn

[jan-norway]

Hi everyone,

My name is Jan and I currently live in Oslo. I recently decided that I need an ebike and figurred that it would be a good idea to build one myself. As I have little knowledge of bicykles I've run into a problem early on, and I'm hoping to get some help here.

My bike details:
Taifun delta trekking bike,
700C wheel size,
13,5 cm room between rear forks (sems to be able force them to ca 15,5),
Rim brakes,
quick release wheels,
Not aluminium frame (just tested with a magnet).

I recently received from Golden Motor in China:
Prokit 901 500W for 700C rear wheel, 6 speed casette,
LT36V12AH battery, twist throttle, cruise control, and controller, rak 001.   

My question is regarding installation of the motorized rear wheel. There seems to be so much friction an rolling resistance that I guess something has to be wrong with the way I try to mount it it.  The wheel came with, for either side, a disc brake tube (metal sylinder), one washer with a tap, one washer without a tap and a bolt

[jan-norway]

(Continuing - sorry for splitting)

As I don't have disc brakes on my bike I'm not sure what to do with those disc brake tubes. Should they just be be put on first on both sides and get a washer next to them?  Wont they make alot of friction? Should I have specifically orderred a kit for a bike without disc brakes?

On the right side the db-tube will be about 1 mm outside of the sped casette, and I then need two washers to get clearance between the frame and the speed casette. On the left side the db-tube, washers and bolt was already fitted on the motor cable leaving no choice. (I guess I should post pictures, can do later)

I mounted it this way, which seemed like the only option with what I had, and there was much friction in the wheel when I spun it using the pedals. The wheel stopped spinning after maybe 3 seconds. After I had been  spinning it a while, a sound came (bad? ) and the wheel is now very hard to turn.

If someone would give me a tip I would very much appreciate it!  I apologize for the poor english and the newbie-character of the question.

Thank you,

Jan

[Bikemad]

Hi Jan andto the forum.

The spacer tubes and washer should be fitted as shown here:



If the wheel is tight to turn (in addition to the normal magnetic resistance of the motor) then try turning it slowly by hand and listen for a rubbing sound and see if you can locate the cause.

Check to make sure there is clearance at the brake blocks, and between the tyre and the frame.
If nothing is touching either the rim or the tyre, then it has to be somewhere on the axle or the motor.

Make sure there is clearance between the washer and the freewheel unit, but if nothing appears to be touching on the axle area, try disconnecting the three thick Yellow, Green and Blue phase wires from the motor (but don't allow the loose terminals to touch each other) and then see if the wheel turns more freely.

Please let us know what you find.

Alan
 

[jan-norway]

Thanks a lot for the reply Bikemad. I really appreciate it.

I had another long look at it today, checking if the wheel was touching the brakes, frame etc., which it wasn't. The wheel is mounted according to the picture ( I have a gear cluster too which is not on the picture). It is now.

When it comes to space between the washer and the freewheel unit, I was a bit unsure what you meant. I assume freewheel is the innermost part of the gear cluster that can move independently of the rest? Well, I can't really say 100% if there is space there. It was really marginal. The disc brake plate-tube was only looking 1 mm or so outside of the gear cluster, but if nothing has moved it should be some free space there. It looks as if there is space there.

Testing today: At first there was a scraping sound at a specific point in every rotation and a bit of nagging resistance with it. This sound came from within the motor as far as I could tell. Then, somehow, after I had been rotating the wheel for some time using the pedals the sound and resistance at that specific point was gone. The wheel seemed to be spinning ok. There was still much more resistance than without a motor (I guess it was comparable to having a dynamo on a normal wheel, probably a bit less). But this is probably the magnetic resistance in the motor that you mentioned, right? There was also some kind of whistling sound when spinning fast, but this sounded like something that could be normal.

I continued spinning it for some time to check if it really could be ok now. After some intervals of spinning fast, it came to a sudden stop. There is now a great resistance in the motor. As some sort of brake should be constantly on. It is possible to turn it still, but force is needed. I remember it was in the same state yesterday as well, but then it disappeared somehow pretty soon.

Any idea what this could be?

I tested it once again now, great resistance at first, then suddenly it was gone for a sec, back again for a few moments, gone for a sec, and then back again. So it comes and goes.

I'm not sure if I'm making matters worse by trying to spin it all the time.

You wrote that I should try to disconnect the phase wires (from the control box I guess?). Could it be that the difficulties I'm having now is because I haven't installed everything, haven't connected any of the wires, controller or battery etc.? And that the motor enters some kind of brake mode?

If not, would it be very unwise to install everything and see what happens when I turn it on?

Thanks again for the help!

Jan

[Bikemad]

Jan, the freewheel unit is another name for the gear cluster assembly.
The washer on the end of the spacer must not touch the outer end of the gears (sprockets), or the outer end of the fixed portion which screws onto the hub (the centre part of the whole gear cluster).
If the washer is touching either part it will cause unnecessary friction, which can probably be eliminated with a bit of gentle filing on the washer where it touches against the freewheel assembly if required.

I haven't installed everything, haven't connected any of the wires, controller or battery etc.? And that the motor enters some kind of brake mode?

From your description, it sounds as if two of the phase wire connectors are simply touching against each other.

This is precisely the reason why I mentioned this:

(but don't allow the loose terminals to touch each other)

So make sure the three connectors are all kept separated from each other and then try turning the motor again to see if the resistance has gone.

Then try holding all three connectors together and see just how strong rheostatic dynamic braking can be.

A word of warning:
When you have the controller fitted and wired to the motor, do not try spinning the motor very fast by winding the pedals without the battery being connected and turned on. If you spin the motor fast enough, the voltage generated can become high enough to actually damage the controller if there is nowhere else for it to go.

Alan
 

[jan-norway]

Thanks for your help Alan - it was exactly as you said!

I have now installed everything and tried to test it today, but unfortunately I ran into another difficulty.

When I twist the throttle the motor kinda tries to turn the wheel, as if it is banging against an invisible wall. After half a second of "trying" it stops, and if the throttle is still twisted a sound comes from the motor which resembles a valve opening and letting gas out.
 
Sometimes when I try to turn it on and twist the throttle, it doesn't try to rotate the wheel at all. But if I spin the wheel manually and twist the throttle it will try. When the wheel spins and I twist the throttle, it stops abruptly with kind of a banging noise.

Any thoughts on what that might be?

Some other information:
The lights on throttle are indicating that the battery is full. The horn makes a loud beep when pressed. It also makes a not-so-loud high-frequency sound when the battery is turned on. The power brakes halts the wheel when pressed.

The trick mentioned in the manual (pressing cruise control button 5 times while squeezing the brakes) does not appear to have any effect.

I don't have a voltmeter at hand. The battery was charged until the green light came on.

The powerswitch cable was a bit unprotected towards one end. I covered it with some tape. The red battery cable was not 100% either, there might be poor connection there. But if that was the problem there wouldn't be any response from the motor at all I guess?

Thanks again for helping me out here!

Jan

[Bikemad]

It sounds to me as if it might be a miss-match between the hall sensors and the phase wires. Double check that you have the Yellow Green and Blue thick phase wires connected to the correct colour wires at the bullet connectors and that the wires are going to the correct terminals on the controller.
If these are correct, check that all the other coloured wires are connected exactly as shown on pages 13 and 14 of the user guide. Check closely that the wires in all the block connectors for the hall sensors are in the correct order and have not been inadvertently placed into the wrong positions during assembly.

Hopefully it will just be a couple of crossed connections that just need to be swapped over again.



Alan
 

[jan-norway]

Correct again Alan! The yellow and blue hall sensor wires were swapped. After correcting them, everything seems to work. Looking forward to my first ride now

Thanks again Alan for being so helpful! Invaluable for a newbie. Maybe I can help you sometime

The sun is shining from a blue sky here in Oslo which means that I have got to get this thing outside.

Have a great day everybody!

Jan

[Bikemad]

Hi Jan, I'm glad I was able to help you with your problem, and I'm very relieved that it was something relatively quick and easy to locate and fix. I'm sure you'll have enjoyed every minute of your first power assisted ride.
Please let us know how the ride went, as we'd love to read about your first impressions of your eBike experience.

Alan
 

[jan-norway]

I think the bike is working even better than I was hoping for. Yesterday,  I went on a ride up the mountains and its amazing to be pushed up those hills so easily. I found some  places to rest with great views of the city and the fjord. With the throttle still indicating full battery, I went into the "outback" of Oslo, called Nordmarka. There, it appears to be a network of roads which are used for cross-country skiing in the winter that are perfect for biking in the summer. Because of health problems I havent been able to check this out before. Beatiful nature. The e-bike has definetly opened a new dimension for me and I feel like Im discovering my city all over again:) Looking forward to the summer now.

So Alan, if you ever wanted to check out the Norwegian capital from the seat of an ebike, I can hook you up!

The only issue I had was that a couple of wires disconnected a few times. But as I was fixing it, peole came asking me what I was doing, and I got to tell them about my ebike etc, which was fun aswell.

[jan-norway]

(Needed to split it up again, writing on an e-reader)

I was wondering if it is possible to get even more torque if I connect the controller to a computer and adjust the ampere-settings?  Or would I need a battery with higher voltage to do that? I now have 500W motor with 36V battery.

I guess I'm just curious about the possibilities. 500W seems to be enought for me. Would a 1000W use the batery faster than a 500 would when going at the same speed on the same road? ( guess I should by a ebike for dummies book soon).

I think I was underway maybe 3.5 hours yesterday, but my battery was still supposed to be at full capacity. I was going slow, but still I kind of doubt it.. well, I'm not complaining

Jan