No freewheel on new BPM 2 hub from BMS battery

[romarin123]

Hello all

Since this is my first post, I will introduce myself: long time bicycle enthusiast which went from diamond frame, to recumbents and now wants to convert them to e-bikes due to knee problem. I own two recumbents one I built myself ( I do TIG) and a Rans Stratus LE. Now the bad stuff. I ordered a 48 v 12 ah battery and a Bafang BPM 2 motor mounted on a wheel from BMS batteries. Upon arrival I noticed the wheel was very hard to turn by hand (in the correct direction shown by arrow on hub). There is no freewheel. Upon complaining I was told by one BMS battery person 'it is built like that' and by technical support 'sorry we cannot hep you on that'. Now The Bafang BPM 2 is a geared motor and I purchased it believing it freewheels. Can anybody tell me if the BPM 2 has that feature ? Thanks

 

[KirstinS]

I have this exact motor from bms and it does freehwheel !

 

[Alan Quay]

Check that the wires from the motor are not shorted together. That'll cause it to be tight.

If you are missing an actual freewheel, you just use the one from the wheel you take off.

Also, the motor will be stiffer to turn in the opposite direction of normal rotation. Are you sure you have it the right way around?

 

[romarin123]

Thank you Kirstins for confirming that the motor should freewheel. BMS battery is trying to convince me otherwise. Thank you also Alan for your ideas. I have checked and no wires are touching , as the motor is presently not powered and the wires are not connected. Yes I could have tried to turn it in the 'wrong' direction, but this is not the case. I made sure that I turn it in the sense of the arrow on the hub. When I turn it in the opposite direction I feel the gears engaging and it becomes of course much tougher to turn. I was told by Mr. Bruce Teakle ( he has a blog on changing gears in a Bafang motor) that there is no way to adjust the 'tightness' of the axle as in an ordinary hub. Is that the opinion here also ? Should I open the thing and explore ? Thanks for the input as it makes it already easier knowing I have knowledgeable help.

 

[awol]

Should I open the thing and explore ?

If it's anything like my Bafang CST motor then I would open it up, it's easy with only about 4 main parts+fiddly washer's, instead of sending it back. My Bafang motor came from another supplier with a squeaking annoying clutch and got no help from the supplier so I opened it up and put a new clutchplate in for about £25. It then ran so much quieter and smoother.

 

[romarin123]

If it's anything like my Bafang CST motor then I would open it up, it's easy with only about 4 main parts+fiddly washer's, instead of sending it back. My Bafang motor came from another supplier with a squeaking annoying clutch and got no help from the supplier so I opened it up and put a new clutchplate in for about £25. It then ran so much quieter and smoother.

 

[romarin123]

Hello Awol. I will follow your advice and hold before sending it back. It is the newer model with the casing held by screws so it is not a bear to open. I was told on another forum that the problem might only be that the motor has to be sort of 'broken in' for the freewheel to operate in a normal fashion. So as for now, my feeling is to get it to work electrically ( I am missing a few parts for that, among others the controller) and then see if the 'stiffness' changes. If not, I will investigate the insides and report. Thanks

 

[Alan Quay]

Thank you Kirstins for confirming that the motor should freewheel. BMS battery is trying to convince me otherwise. Thank you also Alan for your ideas. I have checked and no wires are touching , as the motor is presently not powered and the wires are not connected. Yes I could have tried to turn it in the 'wrong' direction, but this is not the case. I made sure that I turn it in the sense of the arrow on the hub. When I turn it in the opposite direction I feel the gears engaging and it becomes of course much tougher to turn. I was told by Mr. Bruce Teakle ( he has a blog on changing gears in a Bafang motor) that there is no way to adjust the 'tightness' of the axle as in an ordinary hub. Is that the opinion here also ? Should I open the thing and explore ? Thanks for the input as it makes it already easier knowing I have knowledgeable help.

Your problem with BMS battery is about how you are phrasing the problem.

Even I (as a native speaker of English) had to read a couple of times.

A freewheel is a specific piece of equipment. The screw on type sprockets, similar to a cassette but threaded as opposed to keyed.

The BPM is not supplied with a freewheel. That's what the guys at BMS trying to tell you.

Obviously the motor should offer virtually no resistance when rolling along.

 

[anotherkiwi]

Obviously the motor should offer virtually no resistance when rolling along.

And once you put on a free-wheel or a cassette it will turn freely.

 

[Deleted member 4366]

I'm having trouble understanding what you're saying about the motor, so I guess it will be even worse for a Chinese person.

I don't know what you're doing to test it because you didn't describe how you were doing it, but I offer you this advice: You don't take any notice of arrows on the hub. The disc brake fixings will show which way round it goes. You can't test a new motor by turning the axle with your fingers. You have to put it in a frame with the axle clamped. Even then, without a rim, it will appear stiff until it's done a few hundred miles. When the axle is clamped, you can feel the gears turning when you rotate it in the backwards direction, but not in the forward direction. If you can feel the cogging in both directions, the clutch is stuck, which you can often free by giving the wheel a whack in the forward direction.

 

[romarin123]

Hello all contributors to this thread. I apologize for my broken english as this is not my mother tongue. I agree that that the term freewheel can be confusing since in english, it is in both a noun (a device) and a verb. Imagine indeed how confusing it must be to the chinese! So I made a short video to show BMs battery the problem, a picture being worth a thousand words. The wheel was clamped in an appropriate support. I tried to make it spin by hand (in the correct direction which does not engage the gears) and while it spins, it does not do so 'freely'. D8Veh your suggestion is good , but I can clearly feel the gears engaging in the 'wrong direction' and not engaging in the other direction so I do not think it is a 'stuck' clutch. Also, since it is a front wheel I cannot and will not install a cassette. Be that as it may, I got the answer from their engineer that 'Bafang motors are tight' and I was told to assemble the bike and test it. This rejoins other's suggestion to 'break in' the wheel. It will take me some time to get to that point and we shall see... I will report. Thanks again.

 

[Deleted member 4366]

I think you were worrying about nothing. Once you have it all built up, you'll see that it's everything you hoped for.

You have to take care when fitting a BPM front motor. The torque can break your forks if you don't do it right. What type of forks does your bike have?

 

[KirstinS]

Mine did free up after 50 miles or so, just as d8veh suggests

 

[romarin123]

Hello d8veh Sorry I was away. I think the concensus is that I should 'break in' the wheel. So I will do that as soon as I build the thing. As for the fork, they are nothing special took them from run of the mill 20'' bicycle. They are steel , but I do not know the exact type, but no fancy lightweight alloy. I have ordered a pair of torque preventers from BMS battery, but I would welcome any suggestions on this issue.

 

[romarin123]

Hello again. I forgot to mention that the forks are not 'mountain bike' type (round straight tubes), but rather the 'slender' tapered and slightly curved types. I could post picture if required.

 

[Deleted member 4366]

I'd fit at least one torque arm, which needs to be properly anchored, not with a jubilee clip unless it's one of the rigid type.

 

[jonathan75]

I'd like to add that my Bafang motors sometimes resisted freewheeling, heavily, when wired up with power but miswired. It's important to note that sometimes the plastic connectors in a kit with the various coloured wires stuck in them, aren't consistently lined up on the male and female sides even when the parts are from the same seller or manufacturer. That has caused things to go wrong for me including a failure to freewheel, so I strongly recommend checking that all the wiring is meeting up as it's supposed to.

 

[romarin123]

Thanks d8veh for the advice on the torque arm. Hello Jonathan75, I will make sure everything is wired correctly when I get to this point. Initial test on freewheeling was done without connection to power, manually on a wheel stand. I expected the wheel to 'freewhweel' or if you wish, to spin effortlessly when turned by hand in the 'correct' direction that is the direction in which the gears do not engage. It did not. I am in the process of building the bike and will be able to test the wheel with power. I would expect that if everything works as it should and everything is wired correctly , wheel should continue to spin for a while after power is cut of. If not, I will try to put some miles on it to 'break it in' and see if things improves. Will report then about results.

 

[romarin123]

Forgot to mention that I verified that no wires are shorted when I made test by hand. I do not know exactly how these motors work, but I would have expected that when gears are not engaging the only resistance to rolling would have come from the axle bearings. But I may be wrong. We will see how things unfold and as d8veh said I maybe worrying about nothing.

 

[1boris]

Thanks d8veh for the advice on the torque arm. Hello Jonathan75, I will make sure everything is wired correctly when I get to this point. Initial test on freewheeling was done without connection to power, manually on a wheel stand. I expected the wheel to 'freewhweel' or if you wish, to spin effortlessly when turned by hand in the 'correct' direction that is the direction in which the gears do not engage. It did not. I am in the process of building the bike and will be able to test the wheel with power. I would expect that if everything works as it should and everything is wired correctly , wheel should continue to spin for a while after power is cut of. If not, I will try to put some miles on it to 'break it in' and see if things improves. Will report then about results.

No,it doesn't spin effortlessly by hand.Its actually a little hard to turn when new.So I believe your motor as other have said is perfectly ok