Tongsheng - chain slipped off now too much resistance and can't pedal

[scrolltonowhere]

I'm having an issue with my TS ebike conversion. I did this last year and it was riding fine. I just brough it out as it sat in the basement for the winter. The first ride was smooth but today's second ride the chain fell off the front ring. After the chain was set properly back over the front ring, I noticed pedaling was less smooth and had a lot more resistance. On my way home, I shifted and then the bike decided it didn't want to let me pedal any further. I was able to walk the bike back home which was fortunately only a few blocks.

One possibly related issue that occurred last fall one of the pedals slowly started coming loose as I pedaled. I don't know if this is related.

Does anyone have any ideas what could be going on with my bike?

 

[docw009]

One of the pedals is loose? You mean the pedal arm, not the pedal? This may cause the torque sensor in the motor to not register consistenmt pressure on both sides, so the motor gets less assistor maybe none at all. Fix the loose pedal.

 

[Chalo]

Pedal or crank? Where did the chain fall off to? Did you try to pedal after the chain fell off, and if so, did the chain gouge anything in the process?

To me it sounds like you need to consult somebody who has at least a minimal understanding of bike maintenance and can better describe what happened. Or maybe take some pictures?

The easy route might be to take it to a bike service shop and let them take care of the problem.

As for me, I never recommend e-bike conversions to anybody who doesn't already know how to keep their pedal bike running.

 

[scrolltonowhere]

One of the pedals is loose? You mean the pedal arm, not the pedal? This may cause the torque sensor in the motor to not register consistenmt pressure on both sides, so the motor gets less assistor maybe none at all. Fix the loose pedal.

Sorry if that wasn't clear. It was actually a crank that came loose last fast that I fixed right away.

Pedal or crank? Where did the chain fall off to? Did you try to pedal after the chain fell off, and if so, did the chain gouge anything in the process?

To me it sounds like you need to consult somebody who has at least a minimal understanding of bike maintenance and can better describe what happened. Or maybe take some pictures?

The easy route might be to take it to a bike service shop and let them take care of the problem.

As for me, I never recommend e-bike conversions to anybody who doesn't already know how to keep their pedal bike running.

Hi again Chalo. The chain fell off the front ring toward the frame of the bike. So I believe you saw my comment on another thread about trying to get some screws off the motor housing as a suggestion from another forum member. As my motor has now been removed from the bb I tried pushing the bike again. With no cranks or motor on the bike will roll forward but not backward. Now I'm thinking this could be something completely unrelated to the motor. I guess you have to be careful of whose advice to take on this forum. They told me to rush in and just take the motor apart and I stupidly listened.

I did basically replace every hardware piece on the bike last summer including the cassette. I'm wondering if this issue can be somehow related to the cassette. Sure, I'm not great at bike maintenance but I want to learn.

Edit: I just took some photos of the cassette. It looks a little like the smallest cog may be misaligned. Could this be the issue?

 

[scrolltonowhere]

 

[amberwolf]

With no cranks or motor on the bike will roll forward but not backward.

Is it the rear wheel or the front wheel that won't rotate in reverse?

Does the same problem happen when you flip the bike upside down and manually rotate the wheels?

Does the wheel *never* rotate in reverse *at all*, or does it start to do so and then "jam"?

If the latter, what other part of the bike also moves while you are reverse rotating it, and stops before or at the same time as the wheel?

If it is the rear wheel, then with the chain pulled off the cassette so it is away from the wheel entirely, not touching any part of the wheel or cassette, does the wheel still not rotate in reverse?

 

[From-A-To-B]

As for me, I never recommend e-bike conversions to anybody who doesn't already know how to keep their pedal bike running.

I resonate with this. DIY ebike conversions are great. I went a little spendy with my own conversion with a 1000W Leaf rear wheel kit. I believe I came out around $1250 for the whole bike, including a DIY 48V20AH battery from Lishen cells. I know many others may have spent much more, and many have spent less. I built another bike for my partner after we sold the car, and her build came out to give or take $800, less the donor frame we already had.

Anyway, the point is: our DIY bikes are rather fiddly. I’m always adjusting something, rebuilding something, or improving something. I enjoy the continual build process, but it’s not for everyone. And for someone without the know how and inclination to learn bike mechanics, upkeeping a conversion ebike may be a bridge too far.

I was excited to get more performance for less money compared to a factory built ebike. But my experience after a few thousand miles is that you cannot set-and-forget a DIY conversion.

 

[scrolltonowhere]

Is it the rear wheel or the front wheel that won't rotate in reverse?

Does the same problem happen when you flip the bike upside down and manually rotate the wheels?

Does the wheel *never* rotate in reverse *at all*, or does it start to do so and then "jam"?

If the latter, what other part of the bike also moves while you are reverse rotating it, and stops before or at the same time as the wheel?

If it is the rear wheel, then with the chain pulled off the cassette so it is away from the wheel entirely, not touching any part of the wheel or cassette, does the wheel still not rotate in reverse?

It's the rear wheel that's not rolling. It's the same case when upside down and when I manually rotate. I can rotate the rear wheel with some applied force but it stops abruptly meaning it's not possible to let the wheel spin freely.

I'm not sure what you mean by what other part of the bike also moves while reverse rotating. I don't think any other part if I understand what you're asking.

I'm not able to get the chain off the cassette right now since it's indoors and handling the chain is pretty messy. Maybe I'll take it into a bike co-op tomorrow that's supposed to be open. I appreciate your help in trying to help me troubleshoot this.

 

[gromike]

You know, you can watch the Park Tool video on cassette removal/service. Probably a good thing to watch even if you're bringing it in.

 

[amberwolf]

All of the questions are designed to help you observe exactly what is happening on the bike when it is working correctly (forward motion) and when it is not (backwards motion). It may take many repeats of tests to see everything that is happenign, or it may be obvious where the problem is pretty quickly, but careful observation will show you where the problem is.

Without actually being there to see and feel what you have and how it moves and stops, I can't tell you what might actually be happening, but there are a limited number of possibilities.

It's the rear wheel that's not rolling. It's the same case when upside down and when I manually rotate. I can rotate the rear wheel with some applied force but it stops abruptly meaning it's not possible to let the wheel spin freely.

Well, since the rear wheel spins forward freely but not backwards, does it stop instantly when you rotate it backwards after rotating forwards, every time?

Or does it take some distance to do so?

If so, how much rotation does it make?

Does the cassette's freehub click during this like it does in forward rotation?

Or is it silent until it stops the wheel from rotating?

I'm not sure what you mean by what other part of the bike also moves while reverse rotating. I don't think any other part if I understand what you're asking.

If the chain is touching the cassette then the chain should move too. If it doesn't, then the chain is jammed and you should find out what's wrong with the chain or replace it. If it isn't the chain itself it would have to be something the chain is attached to or passing thru.

If the chain is not touching the wheel or the cassette, then it won't move with the wheel.

If the chain is touching the wheel or cassette, and also touches some other part of the bike, does that other part also move when the wheel stops? Like the derailer? Or the chainguard or front derailer, if any?

If the chain does touch wheel/etc and stops moving when the wheel does, does it have more tension on it then?

Does pulling on the chain from the "top" (like the front chainrings would) also spin the wheel forward?

Etc. Observing what moves and what doesnt' move and what causes other parts to move will find the part stopping it from moving.

I'm not able to get the chain off the cassette right now since it's indoors and handling the chain is pretty messy. Maybe I'll take it into a bike co-op tomorrow that's supposed to be open. I appreciate your help in trying to help me troubleshoot this.

Since you don't have any cranks / motor / etc on htere, which means you have no front chainring, then if you have gloves, or some paper towels or a rag, etc, it's pretty easy to shift the derailer out all the way to the right, then sipmly lift the chain off the cassette's teeth, and either ziptie or hold the chain away from the cassette so nothing can possibly restrict wheel movement except for the wheel itself.

Then it is easier to tell if
A) the wheel is catching on something on the frame, or a brake arm / pad / etc that it doesn't do in forward motion
B) the cassette is jamming on the frame and it's built in freewheel allows forward motion anyway, while preventing reverse rotation
C) the wheel now rotates freely meaning the problem is with something the chain itself passes thru, like the derailer and it's jockey wheels, or the front chain guide/derailer if the bike has one.

Etc.

 

[scrolltonowhere]

All of the questions are designed to help you observe exactly what is happening on the bike when it is working correctly (forward motion) and when it is not (backwards motion). It may take many repeats of tests to see everything that is happenign, or it may be obvious where the problem is pretty quickly, but careful observation will show you where the problem is.

Without actually being there to see and feel what you have and how it moves and stops, I can't tell you what might actually be happening, but there are a limited number of possibilities.


Well, since the rear wheel spins forward freely but not backwards, does it stop instantly when you rotate it backwards after rotating forwards, every time?

Or does it take some distance to do so?

If so, how much rotation does it make?

Does the cassette's freehub click during this like it does in forward rotation?

Or is it silent until it stops the wheel from rotating?



If the chain is touching the cassette then the chain should move too. If it doesn't, then the chain is jammed and you should find out what's wrong with the chain or replace it. If it isn't the chain itself it would have to be something the chain is attached to or passing thru.

If the chain is not touching the wheel or the cassette, then it won't move with the wheel.

If the chain is touching the wheel or cassette, and also touches some other part of the bike, does that other part also move when the wheel stops? Like the derailer? Or the chainguard or front derailer, if any?

If the chain does touch wheel/etc and stops moving when the wheel does, does it have more tension on it then?

Does pulling on the chain from the "top" (like the front chainrings would) also spin the wheel forward?

Etc. Observing what moves and what doesnt' move and what causes other parts to move will find the part stopping it from moving.






Since you don't have any cranks / motor / etc on htere, which means you have no front chainring, then if you have gloves, or some paper towels or a rag, etc, it's pretty easy to shift the derailer out all the way to the right, then sipmly lift the chain off the cassette's teeth, and either ziptie or hold the chain away from the cassette so nothing can possibly restrict wheel movement except for the wheel itself.

Then it is easier to tell if
A) the wheel is catching on something on the frame, or a brake arm / pad / etc that it doesn't do in forward motion
B) the cassette is jamming on the frame and it's built in freewheel allows forward motion anyway, while preventing reverse rotation
C) the wheel now rotates freely meaning the problem is with something the chain itself passes thru, like the derailer and it's jockey wheels, or the front chain guide/derailer if the bike has one.

Etc.

Thank you amberwolf for all the time and effort you've spent on helping me troubleshoot. I put the motor back on and fortunately it powers on. I'm glad I didn't muck anything up there


So I found the probably issue and I think I can rule out the motor fortunately. I really hope I don't have to open up this motor for any reason sometime down the line because it will be a low percentage chance I'm able to get those last 3 screws off the motor case but I'll cross that bridge if I come to it.

With the motor on and the chain in place, I can spin the pedals and the bike can move with much resistance. Same still goes with the rear wheel. Backward, the rear wheel still won't roll. I found out that one of the screws was missing from my bike rack. It somehow got wedged inside and was pressing very firmly against the smallest cog of the cassette. I took off the wheel and spun the cassette and notice that the ring at the top of the cassette spins unevenly, which means it was probably initially forced an uneven line with the front chainring and knocked it off. Since I had no idea that the bike rack got wedged in this space, it probably further bent the ring it was rubbing against as I biked back home. I took off the wheel and spun it. That ring is the only thing that has an uneven spin. I thought I had the tool to take the cassette off but now I remember I believe I borrowed it from a tool library last year so I can't take it off right now unfortunately.

You can see at the top of the ring in the first picture that the ring touches the first cog. There's a great distance from the bottom Do you think I can just replace this outer ring?

 

[AGS]

To be honest, the whole cassette needs to be replaced. You have broken teeth all over the place.

 

[scrolltonowhere]

To be honest, the whole cassette needs to be replaced. You have broken teeth all over the place.

Really, I think the teeth look fine. I replaced the cassette less than a year ago and I didn't even ride it over winter.

 

[amberwolf]

Now that you point it out I can clearly see the rack mounting tab jammed into the space between the cassette lockring and the frame, in your images posted of the cassette. Sorry I didn't notice that earlier to directly point it out.

FWIW, some of the teeth *are* pretty obviously deformed; it's most clearly visible on the smallest cog where you can see not only the wear-notching but also tip damage where material has been scooped up and out at the chain-engaged edge of the teeth. Such deformations typically lead to chain skipping under torque, and they also wear the chain, which can then damage the other cogs both on the cassette and on the front chainring, which then further wears the chain, etc.

The smaller cog damage is probably from using it for high-torque rather than high-speed, instead of downshifting to the largest cogs for that purpose (like starting from a stop, hillclimbing if any, etc).

Whenever you decide to replace parts, I would recommend replacing the chain, cassette, and front chainrings all at the same time, so the wear already on one part doesn't damage the new parts.

The reason the cassette lockring

Google Search

is cockeyed on there is that it was probalby unscrewed from the freehub by the object jammed between it and the frame.

To fix the problem you should thread it back into the freehub and use the correct lockring tool to tighten it. If the threads on the lockring or the freehub have been damaged you might have to try clearing them first, or if it's bad enough you may have to replace the lockring (a new one will come with the new cassette, usually, if you also replace that for the damaged teeth) and even possibly the freehub itself (some freehub parts are available separate from the wheel hub, so you may not have to relace the wheel around a new hub).

Some reference pages
Shimano Cassettes & Freehubs (and the various info on the rest of the page)

Bicycle Chain and Sprocket Engagement and Wear

Maintenance of bicycle chains.

www.sheldonbrown.com

Chain Maintenance

Maintenance of bicycle chains.

www.sheldonbrown.com

Chain care, wear and skipping by Jobst Brandt

Article by Jobst Brandt about bicycle chains, wear, lubrication and skipping

www.sheldonbrown.com

etc.

 

[From-A-To-B]

Amberwolf gave great, comprehensive advice. That end ring is the cassette lock ring. It compresses your stack of cogs into the freehub (which is attached to your hub/wheel). I wonder if you’ve damaged the freehub body, or just have damaged the lock ring. Check out the threads and see if a new lock ring will thread nicely into place. If in doubt, have a tech at the bike co-op look at it with you.

Ditto about the apparent wear and tear on the cassette teeth. There’s also a large U-shape in between the teeth where material has worn away. As has already been said, chains wear on the cogs, and worn cogs will also accelerate wear on (new) chains.

I’ve always been told to expect a cassette to last 3-5 chains, depending on the frequency of chain replacement. But that’s on pedal bikes, and is only a rule of thumb. Throwing a BB motor into the equation speeds up this wear because you’re feeding more power through the drivetrain.

 

[docw009]

I don't think the Tongsheng is strong enough to wear out a chain. It will burn its internal gears out first,

Wouldn't be surprised that tire is rubbing against the frame, Unless he's crushed a screw or washer on top of the wheel bearings, or have the brakes rubbing, the wheel should always spin freely in one direction without a chain,

 

[amberwolf]

Wouldn't be surprised that tire is rubbing against the frame, Unless he's crushed a screw or washer on top of the wheel bearings, or have the brakes rubbing, the wheel should always spin freely in one direction without a chain,

He already found the problem--see the image below. It's easy to spot if you're looking for a problem--I missed it because I was too busy thinking of troubleshooting steps to post to guide him.

https://endless-sphere.com/sphere/attachments/20230421_221615-jpg.333041/

 

[scrolltonowhere]

Now that you point it out I can clearly see the rack mounting tab jammed into the space between the cassette lockring and the frame, in your images posted of the cassette. Sorry I didn't notice that earlier to directly point it out.

FWIW, some of the teeth *are* pretty obviously deformed; it's most clearly visible on the smallest cog where you can see not only the wear-notching but also tip damage where material has been scooped up and out at the chain-engaged edge of the teeth. Such deformations typically lead to chain skipping under torque, and they also wear the chain, which can then damage the other cogs both on the cassette and on the front chainring, which then further wears the chain, etc.

The smaller cog damage is probably from using it for high-torque rather than high-speed, instead of downshifting to the largest cogs for that purpose (like starting from a stop, hillclimbing if any, etc).

Whenever you decide to replace parts, I would recommend replacing the chain, cassette, and front chainrings all at the same time, so the wear already on one part doesn't damage the new parts.

The reason the cassette lockring

Google Search

is cockeyed on there is that it was probalby unscrewed from the freehub by the object jammed between it and the frame.

To fix the problem you should thread it back into the freehub and use the correct lockring tool to tighten it. If the threads on the lockring or the freehub have been damaged you might have to try clearing them first, or if it's bad enough you may have to replace the lockring (a new one will come with the new cassette, usually, if you also replace that for the damaged teeth) and even possibly the freehub itself (some freehub parts are available separate from the wheel hub, so you may not have to relace the wheel around a new hub).

Some reference pages
Shimano Cassettes & Freehubs (and the various info on the rest of the page)

Bicycle Chain and Sprocket Engagement and Wear

Maintenance of bicycle chains.

www.sheldonbrown.com

Chain Maintenance

Maintenance of bicycle chains.

www.sheldonbrown.com

Chain care, wear and skipping by Jobst Brandt

Article by Jobst Brandt about bicycle chains, wear, lubrication and skipping

www.sheldonbrown.com

etc.

Thank you for confirming this issue. I haven't had the chance to go to the lbs yet to use their cassette removal tool.

I did notice that when riding in the smallest two cogs, there will sometimes be skipping - like you mentioned under torque.

I hope I didn't damage the motor after I rode it home, since I was riding with a lot more torque. I'll see after I get the cassette sorted.