Bafang mid mount motor

RobN

Pedelecer
May 15, 2020
101
29
Hi Guys,
been looking around the forum for a couple of weeks and decided the mid mount motor kit is what I want for my Cube Attention mounting bike. So got the kit and set about fitting it today. Whys it never quite as simple as the Youtube videos?
Anyway got the old bottom bracket, crank etc off and put the motor through the bottom bracket. Now when pushing it through, the motor stops on touching the chain stay but I can still get the securing locking rings on the other side so the motor is fixed in good and tight and secure with the required fixings. The chain ring looks to be in good position compared to the rear chain set ,ie front chain ring is more or less in line with the middle of the rear chain set .
My question is , is it ok for the motor to be up against the chain stay ? There is a couple of mm gap between the bottom bracket and the motor as the chain stay touches first. Does it need a spacer fitting between the motor and the bottom bracket.
Thanks in advance for any help given.
Regards
Rob.
 

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Nealh

Esteemed Pedelecer
Aug 7, 2014
13,904
5,376
58
West Sx RH
If need be use another one so the motor doesn't touch the stay other wise noise will resonate and get on your wick.
 

RobN

Pedelecer
May 15, 2020
101
29
Thanks Nealh,
my only concern is if I space it "off" the chain stay then on the other side it is a bit tight for getting the locking rings on. I have enough thread for the initial lock ring (good and tight with lock thread)but the secondary lock ring only just catches as it is, so any spacer would mean no thread left for the second securing ring.
Do I just put up with a bit of noise from the resonation of the motor? Or is one tight lock ring sufficient?
Regards
Rob.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
13,904
5,376
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West Sx RH
One lock ring is enough, Loctite it and torque it up.
 

RobN

Pedelecer
May 15, 2020
101
29
Well spacers arrived so ive put them on and the motor is now clear of the chainstay.
Only trouble is I needed longer bolts and some washers too, for the support bracket as it now sits further away from the motor. I nearly stripped the motor thread using the shorter ones as they caught then slipped when I tried to tighten them up, anyway I found some in the garage and thread locked everything up.
Ready for the battery now....only it hasn't arrived.
I ordered everything from PSWPower on 24th May. Paid for it all and the motor arrived last week. I asked where the battery was and they said it would be in stock on the 9th June. OK nothing I can do so I will wait. Got a notification today saying battery on way, then one saying refund for battery has been given, then another one saying invoice for battery please pay now so we can send battery..!
When I asked what was happening they said the sum was too big so they had to refund for battery and get me to reorder it?
This is with Alice in China ,who, although her English is better than my Chinese did not make any sense to me whatsoever...!
I just hope it arrives and ive now not been charged extra for it due to a change in exchange rates.
Its a bit frustrating as I just want to get it complete and give it a try.
I wouldn't mind but she said the battery is coming from Germany.
I was considering a kit for my wifes bike but I may look for a different supplier for the next one.
Anyways I will update once the battery arrives hopefully.
Regards
Rob.
 

RobN

Pedelecer
May 15, 2020
101
29
And the latest is ....I was refunded £323 pounds for the $415 dollar battery and ive been recharged £339 for the $415 dollar battery. The thieving gits...!
Oh and still no sign the battery is on its way.
Not right happy to be honest.
 

RobN

Pedelecer
May 15, 2020
101
29
Well battery finally turned up this morning so I got on with fitting it.
Reasonably straight forward but needed a couple of extra rivnuts putting in frame.
I also put some rubber pads in between rivnuts to act as a cushion to stop any rattle or movement of the battery carrier. See pics.
Had to solder on the supplied connectors as the battery came with different connectors to those of the motor. Heat shrinked them for good measure.IMG_0228.jpg
 

RobN

Pedelecer
May 15, 2020
101
29
Some more pics.
I put extra fixing through lower section of battery carrier for extra support.
I still have to fit brake sensors yet and tidy up the wiring but just wanted to check that it worked first.
Had a quick spin up the road and all seems well so tomorrow I will go on proper ride and sort out last bits once im happy with things.
But first impressions are that its just what I wanted.
 

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peter.c

Esteemed Pedelecer
Apr 24, 2018
1,369
393
thurrock essex
That should fly with a hd ;) , hope you got quality cells in the battery, it will eat a cheap battery and spit it out in a few months
 

RobN

Pedelecer
May 15, 2020
101
29
hd?
Battery is 52v 17.5 amp from pswpower.
Not sure what cells in the battery but it came from Germany I believe and was £339 .
Is this likely to be OK?
New to all this so any info appreciated.
Regards
Rob.
 

RobN

Pedelecer
May 15, 2020
101
29
Hi, sorry yes the bbshd motor . I have just checked the battery is actually 48v not 52v. I am still not sure what cells are in it but hopefully decent ones.
When I charged it yesterday it went up to 55v on the display screen?

I have a couple of questions on battery care if anyone can answer them for me?
Do I switch battery off when putting it on charge?
How long do I charge it for, the light seemed to stay red yesterday even when battery was at 55v according to display unit on handlebars?
Display unit never got a full battery symbol on it , it was showing just short of a full battery ?
Do I use battery until totally flat before recharging (someone once told me rechargeable batteries needed to be empty now and again to get a proper full charge into them, maybe talking phone batteries at time)?

When using bike do I keep the motor speed as high as possible rather than letting it slow down in high gear going up hills etc? Is this the cadence? Keeping it spinning higher?

Apologies for all the questions but I just want to get the best out of it.
The Forum has been a great help so far.
Regards
Rob.
 

Gavin

Esteemed Pedelecer
May 11, 2020
316
176
Well done for building the beast Rob. Now it's time to show off your handiwork with some pictures....

With regards motor speed, once you get used to it you'll get a feel for what the motor likes (a bit like a car engine) and what gear you need to be in. If your legs are telling you that you're in too high/low a gear then the motor will probably be agreeing with you.

Under heavy load though (hills, deep mud etc) you wanna keep it spinning quicker (i.e. a lower gear) to give it an easier life and avoid heat build-up
 

RobN

Pedelecer
May 15, 2020
101
29
OK Cheers Gavin,
ive just got to finish a few bits off and tidy up the wiring then I will stick some more pics up.
Thanks for the info.
Regards
Rob.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
13,904
5,376
58
West Sx RH
The battery from empty/lvc will take about 8 - 9 hours to fully charge, the last part of the charge can take some time if the BMS is in balance mode.
If it is 48v then it will see a top voltage of 54.6v, your 55v reading maybe either too high and the BMS hasn't finished balancing or your meter is not very accurate.
 

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