TongSheng Chainwheel offset - dropped chain

Hi. Sorry if this has been covered before - I am just coming to the end of my initial build, and the chain keeps slipping off the chainring, I assume because of the cassette offset against the std TongSheng chainring. See pictures. best approach? The motor is flat again the crank/ bottom bracket. The chain is clearly at an extended angle when in high gear, and no wonder it slips out. I see on the bafangs the common option seems to be a lekkie chainring.

Ideas/ help appreciated.

Tx

I took the stock adapter, after cutting off the arms, and mated it to a Bafang style offset 42t, the smallest that will fit over the reduction gear housing, by drilling some new holes in the adapter to match the chainring.



It did all that could be done to make the chainline better, I do lots of steep climbing in the 46t rear cog, and no dropped chains and decent chain wear also.

I also used some Bafang straight arm cranks to decrease Q factor.

I just use the three "outboard" positions on the cassette with a BBS02 spaced for 8-speed and using 11-17-28 cogs which are all that are necessary with the motor. Shifts fine and excellent wear. The middle cog has a "straight chainline" so each of the other two cogs are only one step in either direction.

Hi. Thanks for the responses ... I am not a mechanic and just started out my journey, so might need some more specific direction please.

So option #1 seems like find a chain ring with inward offset to bring the chain ring effectively closer to the frame. There's not much distance between my current chainring and the frame so assume a smaller 46T or 42T chain ring? Is something like this suitable?

https://tinyurl.com/y5xcgvdc

Option #2 which I must admit I don't understand. "...three "outboard" positions on the cassette with a BBS02 spaced for 8-speed and using 11-17-28..." sounds like you are centering the chain to the middle of the cassette, which I get but how do you create the offset in the first place?

Again I appreciate the help/ patience...am learning.

...and in the spirit of learning..

I did check my chainline, both at the (middle) cassette and the (middle) chain on the chain ring, and both were in the 55cm range, give or take, so it doesn't feel like an incompatibility.

Must admit, even in the limited gears, I am impressed with the TongSheng ... currently have a Haibike with Yammy motor .. very good, but heavy and limited battery, especially as I've now done 7000kms and will need a new battery. NZD1600, without shipping and gst.

So keen to get this issue solved, so I can go up some of the hills which surround me.

Thanks again, for any help.

Been looking around a bit more on chain rings, and thinking of trying the Lekkie Bling Ring HD ... anyone tried to connect to a TongSheng?

https://www.burkescycles.co.nz/products/lekkie-bling-ring-hd?s=recomatic

Seems like a popular choice for the Bafang's BS. Might take the bike round to see what might fit. Views?

Sorry if I was obtuse, but what I meant was that my chainring was offset so far to the right, that the second position on the cassette (from the lock ring) was a straight line to the chainring. Therefore I used three gears from the lock ring, then spacers to the end of the cassette,

re 2old ... "Sorry if I was obtuse" ... my ignorance more like fella...

Ok. so you offset the chainring to the far right which I assume means getting it closer to the frame, which I think is what BigWheels suggestion is. And I assume the best way is to manufacture or find a chain ring with offset like the Lekkie?

As a matter of interest, I took 4 links out of the chain, and this has improved the experience a lot. Will be trying to see if I can fit a lekkie over the weekend ... I don't think my engineering skills are up to much.

looking at the main TongSheng thread, it looks like there are one or two others with a similar challenge, and most seem to choose chainring with offset.

Anyhow, thanks for sharing the wisdom.

Thought I'd give an update. Reducing the size of the chain seems to have fixed it. But will ride over the next 2 weeks and then provide an update. Haven't changed the stock chain ring. Still feels offset to middle gear would improve, and so still might try lekkie at some point. Will update in a couple of weeks.

Thanks for help.

A couple of other things I've noticed. Got a couple of error codes the other day...and at the same time the battery indicator kept changing levels ... hasn't repeated (someone suggested cold weather), but one thing I have noticed is the bars on the battery display, on the tongsheng display, don't seem consistent ... one minute its 3 bars and the next back up to 4. Perhaps firmware trying to be too smart?

Other thoughts over my Haibike:

1. Having flexibility over battery/ frame is great.
2. Power is not light and day, but its definitely more, and its nice to be able to remove speed limit. I've for the 54v/ 750w unit....and battery is ~725 Wh.
3. Its not quite as refined as my yamaha .... setting off is slower, to bring power on, and sometimes I feel the power assist drops off even on high assist, when I am not pushing, whereas Yamaha seems to have priority to movement first torque second.
4. Motor is noisier, but heyho.
5. Ability to service motor is again a big plus.

Upgrades (shortterm) being considered:

1. Bigger rotors....will eventually replace brakes
2. Change Tongsheng crank arms for Bafang straight to prove Q factor.
3. Tires ... and wheels ... bought a cheap bike and the current are cheap cheap.

Medium term I will look at the open source firmware.

Longer term better front fork.

For now I want to test reliability, battery life, waterproofing, chain issue (making sure its fixed), wear-tear and maintenance ... if all goes well, I will be selling my Hiabike (done 7000 kms and battery only gets to ~75% capacity) in the next 6 months.

Check the open source firmware for the motor, more control over parameters and better battery control.

Have ordered the replacement display and Rs232/ USB ... so will find out soon.

Still having a few dropped chains, so will be checking chain length again, and maybe shorten a bit more ... seems to be a bit of an art to this.

LePeche said:

Have ordered the replacement display and Rs232/ USB ... so will find out soon.

Still having a few dropped chains, so will be checking chain length again, and maybe shorten a bit more ... seems to be a bit of an art to this.

Click to expand...

Even on bikes without the torque and speed of an electric motor it's hard to keep the chain on. Offset never seems to be ideal with mid drives either. I had mine OK for a couple thousand km's but it's starting to spit chains again. I'm going to upgrade to a clutched derailleur next opportunity I get.

LePeche said:

Have ordered the replacement display and Rs232/ USB ... so will find out soon.

Click to expand...

Hi, following this thread with interest since I am also in Wellington. Where are you ordering your display and cable from?

Pse check your PMs, a public reply would be 100% OK and might help others, I didn't want to hijack your thread.

Since Tongsheng uses 110bcd spacing for its chainrings, you can use a Narrow/Wide (N/W) MTB chainring to prevent/decrease drops.

SeaBass said:

Since Tongsheng uses 110bcd spacing for its chainrings, you can use a Narrow/Wide (N/W) MTB chainring to prevent/decrease drops.

Click to expand...

Not if the chainline is so whacked as it can be in stock form. That is why I use the offset ring, which is also narrow-wide btw.

re hindesite

Ordered from

https://www.aliexpress.com/item/32909589293.html?spm=a2g0s.9042311.0.0.47b04c4dm6S81c

https://www.aliexpress.com/item/32792513237.html?spm=a2g0s.9042311.0.0.47b04c4dm6S81c

Not arrived as yet. No probs wrt msgs ... and I share as I get to learn also, so all comments welcomed.

re chainring. Took the bike to bike shop and ring wouldn't fit ... more the gap at the front motor. Keen to understand how the clutched gear gets on as an option.

The chain drops due to slackness, when in the lower gear so I doubt offset would help anyway...chain drops over drops/ bumps when in lower gear, and drops from the chain ring. The chain seems to be the correct length so reluctant to shorten further.

...and for the benefit of others.

I bought the motor and battery from

https://www.aliexpress.com/item/32824543593.html?spm=a2g0s.9042311.0.0.27424c4d4ezjm2

https://www.aliexpress.com/item/32860301024.html?spm=a2g0s.9042311.0.0.27424c4d4ezjm2

The Battery guy from great with comms. Both were delivered quickly and in tact. No customs duty.

Outside of the chainring the main issues were:

Getting the motor to fit inside the bottom bracket. Like many I had to use a dremel to grind some of the frame away.
Bottle cage nuts, needed to be refitted as they kept coming loose. Ok now, but ideally need brass versions. Have supported through velcro strap.

Bigwheel said:

I took the stock adapter, after cutting off the arms, and mated it to a Bafang style offset 42t, the smallest that will fit over the reduction gear housing, by drilling some new holes in the adapter to match the chainring.

Click to expand...

Is this BBS02 or BBSHD chainring? How big is offset in mm? BBS is 9mm and HD is 18.3mm, according to Lekkie website. Thanks.

Demion said:

Bigwheel said:

I took the stock adapter, after cutting off the arms, and mated it to a Bafang style offset 42t, the smallest that will fit over the reduction gear housing, by drilling some new holes in the adapter to match the chainring.

Click to expand...

Is this BBS02 or BBSHD chainring? How big is offset in mm? BBS is 9mm and HD is 18.3mm, according to Lekkie website. Thanks.

Click to expand...

It's the BBSO2 kind. You will have to create 5 spacers, so it you go bigger than 9mm you will need longer spacers which could flex, and longer than stock bolts to fit it to the modified stock adapter and you can fine tune that until the ring just clears the nylon cover to get as much as possible which worked best for my bike at least.

Done 1350 kms, and this evening I suddenly get a grinding feeling through the pedal, and a higher/ louder pitched noise from the motor, and a loss in power. I assume the plastic gear is buggered. Don't have time to take motor apart, but am I on the right track?

Must admit ... a bit disappointed its not lasted longer, but other threads/articles suggest replacing the blue plastic gear at ~1300kms. My ride is pretty full on (steep climb) in terms of strain on the gears.

Took the motor apart and no signs of damage to cogs, so cleaned and put back together. Same outcome.

Here's a video ... first off no power assist (no noise), and then full (cog noise)...although the motor provides no assistance what so ever.

https://1drv.ms/u/s!AgJzHivwxSoWgekkJ6hX6RXfpm0Fqw?e=slSNLJ

Have msg'd the shop I bought from on Ali. Will be interesting to see how they respond.

Battery was fully charged and indicated on LCD as full.

If it has a freewheeling clutch in it, that has probably failed; it would allow the motor to run (at hihger revs than normal) while little or no power gets to the drivetrain from it.

Thanks for the steer. Anyone replaced one of these clutches? Is it best to change the individual bearing $15 or the complete assembly $50? I don't have a bearing remover tool. Might see if a local mechanic might be able to do it. Other the later is the only option.

Still talking to the supplier to get their view.

Sort of feels my dropped chain issue led to some stresses on the mechanics. Have since replace my chain ring (narrow/wide), and added a chain guard...just a shame I hadn't done this before this issue turned up.

I see on the other thread, that some people are having similar issues but it turned out to be the blue cog ... specifically the bonding of the inner part to the outer ... feels like I would get more noise from the motor in this instance. But I have the metal cog on order, so assume I can cover this if its the reason.

Will advise.

Well replaced blue gear with metal, and no change. Still don't get power. Have asked for help/ guidance on the other longer thread, but will continue to post on here. Its either the clutch bearing (noting it doesn't seem to align to the wiki symptoms i.e. peddles do not slip) or the PAS ... I do wonder if the sensor has been damaged as my crank/ peddles do wobble like many people seem to report...this my have pushed the magnets too close to the PAS. I might have a look tomorrow. The PAS fix is a new controller unless I can identify the sensor type. Will wait and see what the other thread suggests .. have also contacted the seller on Ali, who has been helpful.