Starter Questions and Gear shifting problem Bafang BBS02

maxitwist

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Hello ebike forum,

Ive installed a bbs02 mid drive on my trek 7x, heres some bits im not sure about that have popped up.

1) I needed to fit the chainring what looks like its is back to front, as there wasnt enough clearing on the frame to fit it the other way, is that ok? It has been running fine so far.

2) Some of my gears are unusable as the chain is not long enough to fit over them anymore with the bigger chainring, should i get a new longer chain?

3) NB - I am unable to change gears while the motor is engaged, just nothing happens when i try shifting gears. Do I need to buy the gear sensors to enable shifting through gears or is something wrong here? Are the gear sensors worth buying?

4) Because of being unable to change gears while riding, I set the bike to always be in the highest gear. Will this drain the battery faster?
b) How long should a 13ah battery last?
c) Will a larger battery increase the top speed as well as distance?

5) I live in a wet country, what should i be waterproofing ?
b) If im leaving the bike outside should i always cover the whole thing with a bike bag, should i disconnect the battery and take it with me.. etc

6) Is the programming cable worth getting?

7) The 6v headlight which came with the set doesnt seem to work, is that worth investigating or should i just get a proper one that doesnt need to connect to the motor.


Thanks for reading and if you can provide any help please do, Q3 is most important imo.
 

Tonerider

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Yes to a new chain. Some pics might be helpful in answering your q's, but you most liukely need to go to a smaller ring with proper offset to clear the chainstay. Might also need to shim the motor with spacers.
 

Vinz

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I agree that you need to install a new chain... but what is the size of the new chainring? I thought most kits came with a 42T or 44T ring - but if you got a 48T or 52T ring, that could be why it doesn't fit the frame, and also why the chain is too short.

I also had a problem with shifting - it would shift really slow, or not at all.
I was able to identify the cause:
My 2020 Giant Roam 3 has the shift and rear brake lines run along the underside of the down tube, and under the bottom bracket. And, the BBS motors are notorious for becoming a little bit loose - so my motor would move just enough to press on the shift cable, and restrict its action. I could verify this when I put the bike on a service stand. Re-tightening the motor mounting nuts only worked for a short while, and the problem would reappear. This is a design flaw in the BBS motors. (The newest Bafang motors use a hose clamp instead of nuts.)
My solution was to install a BBS stabilizer bar... Stabilizer Bar. This bar mounts to the motor and seat tube, and keeps it in place. Problem solved.

My headlight didn't work at first either - till I noticed that I had the wiring reversed. Now it's good. Check your wiring polarity.
I never leave my bike unprotected. I keep it in the garage or in the house when I'm not riding.
I did get the programming cable, as I wanted more control of the 9 PAS levels.

Your situation could be completely different - I'm just reporting what has worked for me.
 

maxitwist

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20220226_151103.jpg
 

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maxitwist

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I believe the new chain ring is 44T
However, the max chainring size according to Trek is only 36T
 

Vinz

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OK, the photos helped.
I'm thinking that since you're running the 44T chainring "in reverse", that you have negatively impacted your chainline. Ideally, when the chain is on the center cog of the rear cassette, it should engage the chainring and form a straight, centered line as viewed from behind the bike. It should not angle to either the right or left side. It can be hard to explain here, but there are plenty of YouTube videos about the chainline you can check out.
Since your chainring forces the chain away from the bike more than normal, it indeed would be difficult for the chain to go into a lower gear on the rear, as the chain cannot be forced to go into an extreme angle - it would pop off of the chainring, or just not shift.
You said that Trek specs a max chainring size of 36T, that's the dead giveaway here.
The included 44T chainring is shaped that way to partially compensate for the amount the gear housing sticks out from the bike - in an effort to keep the chainline as centered as possible.
But you can try installing a 36T chainring designed to fit the BBS02. That will help the chainline issue, but it may not fix it entirely, so you still could have a problem going into the lowest gear. Lekkie makes chainrings for the BBS motors, you can see one here.
There are other vendors that sell Lekkie rings too, I just picked one.
Anyway, that's my take based on your photos. I gather your motor is NOT pinching the shift cable, as was the case with me.
 

HumanPerson

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first of all your chainring on the front is on backwards.
do not go with a 36th chainring on front unless you are climbing mountain.

Vinz must have been drinking. Turn your chainring around. it's on backwards.
 

Vinz

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No, Vinz doesn't drink.
If you read his original post, by some chance, you'd know that the chainring doesn't fit the frame when mounted properly.
Now what advice would you give?
 

maxitwist

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No, Vinz doesn't drink.
If you read his original post, by some chance, you'd know that the chainring doesn't fit the frame when mounted properly.
Now what advice would you give?
Will the lekkie ring definetly fit?
I was into a bike shop today and he asked me a bunch of questions like the distance between the bolts and the distance between teeth and number of gears on my cassete. I thought i only needed to tell him the size im looking for and that would be it. Came home empty handed so.

By the looks of things I should get a new chainring.
A smaller ring will reduce the top speed though right?
 

Vinz

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Will the lekkie ring definetly fit?
I was into a bike shop today and he asked me a bunch of questions like the distance between the bolts and the distance between teeth and number of gears on my cassete. I thought i only needed to tell him the size im looking for and that would be it. Came home empty handed so.

By the looks of things I should get a new chainring.
A smaller ring will reduce the top speed though right?
The Lekkie rings are made to fit either the BBS02, or BBSHD motors. They are not interchangeable, so you need to order a ring for the BBS02 in your case. Since Trek specs a max ring at 36T, it seems to me that the 36T ring is safe. But I strongly suggest you call the vendor before you place an order so you can clear up any concerns. The people I've spoken with at various vendors were always helpful. I'm sure they would accept a return should you have a problem. They might even recommend a smaller 28T Lekkie, depending on how you ride.
I think your bike shop was just trying to fit you with an optimally sized chainring, to best accommodate the gears on the cassette. But you need a ring specifically made for the BBS02. Do you know the size of the previous chanring you were using? Probably something like a 30T, 32T, 34T, etc.
Yes, a 36T chainring will have a reduced top speed, compared to a 44T ring. But you'll gain some torque - which is better for hills and mountain trails.
Again I suggest calling a vendor to discuss with them your situation, before placing an order.
Oh, in your photo it looks like a front shift mechanism on the seat tube, next to the battery. Just curious what it is. One more tip - tidy up on the wiring a bit - you don't want any sticks snagging the wires!
 

Vinz

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If you wanna try something cheaper - from Amazon, who generally has a liberal return policy - go to Amazon and search for this item number
B09FZBKSKV
It's basically a Lekkie ripoff, but could be a good starting point for you.
This kind of ring will help your chainline issue, but again can't fix it entirely - as it doesn't compensate for the amount that the motor housing sticks out from the bike.
 

maxitwist

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Cheers, that was a front derailer, the previous chainring had 22t and 36t. Wasnt sure how to take it off fully so just tied it around there.
 

HumanPerson

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Not sure if that will help but maybe..I know may sound strange...but just maybe..... that along with a spacer or two could put you at
a good place that you may be able to change through some of the cogs eh?

Let us know how ya get on with this mate :)
 

HumanPerson

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Vinz, if you can find this cover somewhere, I think i seen it before but cant find it now it is made by someone else besides lekkie.
That may help our friend here too. That chainline is a bugger once ya go up 3 or down 3 from the direct line for sure
 

Vinz

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Vinz, if you can find this cover somewhere, I think i seen it before but cant find it now it is made by someone else besides lekkie.
That may help our friend here too. That chainline is a bugger once ya go up 3 or down 3 from the direct line for sure
Yes, spacers could help with the original 44T ring, But without being there, it's hard to tell how many spacers would be needed to clear the frame. You can't use too many spacers, as the mounting bolts for the ring may not be long enough for a safe fit. And yes, he could get longer bolts.
The motor cover you mentioned, I believe it is intended to allow use of a special 40T ring that has sufficient offset to fix the chainline problem. You can see it HERE ... but this page is selling the cover, the 40T ring, and a spacer, all for $125. It would be a great solution if it fit his frame. I just worry cause Trek specs a 36T max ring for his bike. Would that one spacer be enough?
Lekkie makes 2mm spacers that fit all 5 bolt holes for just $5, SEE IT HERE. Maybe using one or two of these with the original 44T ring facing correctly would work. Only Maxitwist can tell us how much clearance is needed. And he still might need longer bolts. But remember that using several spacers can negate the improvement to the chainline.
I got lucky with my bike - a 46T Lekkie ring on the BBS02 still clears my frame, no spacers needed.
 

maxitwist

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Appreciate the help guys.
So actually i got the shifter to work and move through all the gears except the lowest one. Havent changed anything, maybe i was just trying to shift under load before, idk. The chainline is ofc at such an angle that if im in the 2nd lowest gear its easy for the chain to come off, so i may still well get the better fitting ring or at least spacers to fit current one the right way, I think there is space for them.

Im really using this as a road/dirt road bike now, not going down any mtb trails with it. If i were then yeah the chain would be flying off all the time, but as it is, its only come off once when i was going over some stones on a downhill.
I plan to do some longer distance trip in the summer, about 40km.
So im wondering how far the bike can go on one charge, found some ebike distance calculator for it and it says i should get 40km out of it.
I notice when im riding typically the motor is putting out 200w,its a 48v 13ah battery, i weigh about 180lbs/80kg.
Does that sound right or should i be looking at getting a second battery for these trips?

The other thing I was wondering is what is the risk of the chain snapping? Should i be carrying around a spare one in case of that? Would hate to get stranded 30km into the journey.
 

Capt Kirk

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Following this for a while, and having gone through the same thing, I will say that the "Lekkie"HD42 gave me the chain line for a smooth shifting 7speed with a 36 Mega gear . It will climb any climbable graded trail in level 7, with a top speed in excess of 28mph. Do I go that fast on a trail, Not a chance. You appear to be looking for speed over climbing power right? You will really need that high range gear when climbing any steep hill as the lugging will over heat your motor. The shift sensor, if properly installed will allow smooth shifting if there is no load on the chain, try to shift before you need it. As far as the 13 AH battery my BBSHD runs in level 3-5 while I am running, and will give you over 20 miles of PA on average flow trails. Only carry spare parts if you want to ride back out, I still carry a new chain a few links and tools to fix most mechanical issues. One last thing, look on line for an "Internal tooth "Star" lock washer 49mm OD X 32.5mm ID for keeping the drive lock nut tight.
 

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