Middrive Chain popping

S

speedyebikenoob

1 kW
Joined
Feb 6, 2019
Messages
333
I have a middrive e bike and I noticed today when riding around that if you are in too high of a gear (3-4-5-6) and you gun it from a standstill the chain starts to "pop". It doesn't necessarily slip, but it's kind of concerning. What are the reasons for this happening? Is it because the chain is not lubricated enough or something? Also I have to chains, one from the motor to the crankset, and one from the crankset to the rear gears. I'm not sure which one is doing the popping but I feel like it's the motor chain. This isn't a huge problem for me or anything because it just happened that today on accident I started in like fourth gear, I usually start at first and make my way up and the chain doesn't pop.
 
higher gears have less sprocket teeth engaging the chain in the back, so the harder the chain pulls on it the more likely it is to slip.
 
amberwolf said:
higher gears have less sprocket teeth engaging the chain in the back, so the harder the chain pulls on it the more likely it is to slip.
Click to expand...

Is there any known way to prevent this? I'm guessing the more pops there are, the more unnecessary wear it puts on your drivetrain.
 
Grantmac said:
Don't start in the wrong gear.
Click to expand...

What do higher powered bikes do though to prevent this? My bike is only about 2400 watts, and I always make sure to start in the lowest gear now, so it's not a problem for me, I'm just kind of curious as to what people with 4k+ watt middrives do.
 
I'd assume they start in the right gear. ;)

Other ways to prevent it:

Increase chain tension so it can't lift up over the teeth. This then wears the chain out faster at the pins.

Increase derailer spring tension so it keeps the chain wrapped on the sprocket. This may make it harder to shift. (much harder, if you have to increase it too much).

Use only one gear, and use a chain tensioner that does not have a spring, or has a very strong one, to keep the chain wrapped around the sprocket.

Increase chain wrap, so more chain links contact more sprocket teeth (this is what happens automatically when you use larger sprockets). This may also make it harder to shift (possibly impossible, depending on the amount of wrap you have to use).


None of the solutions are optimal, they all have disadvantages.

It's much simpler just to use the gears as they were intended. ;)



FWIW, I've never been a powerful cyclist, and with my knees and other joints deteriorating as I get older, I'm nowhere near as powerful as I was a decade or two ago. Yet, I could still pop chains on the smallest sprocket in the back, if I slammed on the pedals hard at a stop in the wrong gear...just with my legs (especially if I was pulling a loaded trailer full of dog or dog food).
 
Sounds like you might have a stretched chain, which makes them start skipping even when used with a new rear gear set.

Stretch your chain fast, by starting in too high a gear all the time, along with wasting your battery power, and heating up your motor more than it should be.
 
Driving the chain is making some basic tuning and riding habits mandatory. Proper chainline, proper tension, matching chain/gears... and proper shifting for the load/speed.

No magic can save a bad tuning, nor a bad rider. :twisted:
 
worn chain

and or sprockets
 
amberwolf said:
I'd assume they start in the right gear. ;)

Other ways to prevent it:

Increase chain tension so it can't lift up over the teeth. This then wears the chain out faster at the pins.

Increase derailer spring tension so it keeps the chain wrapped on the sprocket. This may make it harder to shift. (much harder, if you have to increase it too much).

Use only one gear, and use a chain tensioner that does not have a spring, or has a very strong one, to keep the chain wrapped around the sprocket.

Increase chain wrap, so more chain links contact more sprocket teeth (this is what happens automatically when you use larger sprockets). This may also make it harder to shift (possibly impossible, depending on the amount of wrap you have to use).


None of the solutions are optimal, they all have disadvantages.

It's much simpler just to use the gears as they were intended. ;)



FWIW, I've never been a powerful cyclist, and with my knees and other joints deteriorating as I get older, I'm nowhere near as powerful as I was a decade or two ago. Yet, I could still pop chains on the smallest sprocket in the back, if I slammed on the pedals hard at a stop in the wrong gear...just with my legs (especially if I was pulling a loaded trailer full of dog or dog food).
Click to expand...

That's interesting, you still must be stronger than me though because I've never been able to get the chain to pop on a normal bicycle :D , but, I don't think I've ever started in the highest gear on my pedal bike so maybe I could.
 
MadRhino said:
Driving the chain is making some basic tuning and riding habits mandatory. Proper chainline, proper tension, matching chain/gears... and proper shifting for the load/speed.

No magic can save a bad tuning, nor a bad rider. :twisted:
Click to expand...

Ooh I see, okay I just set my tension and my derailleur once and forgot about it, maybe I'll go back and retune it if the popping starts to occur in the lower gears. I usually try and keep my motor about 2/3s up in the rev range on flats and if I'm going uphill I run it closer to redline just so it won't overheat. I'd say my chainline is okay, but I could probably make it better by adding a couple of spacers between the chainrings in the front.
 
speedyebikenoob said:
Grantmac said:
Don't start in the wrong gear.
Click to expand...

What do higher powered bikes do though to prevent this? My bike is only about 2400 watts, and I always make sure to start in the lowest gear now, so it's not a problem for me, I'm just kind of curious as to what people with 4k+ watt middrives do.
Click to expand...

They start in the correct gear, or if starting on the flat in a higher gear they add power slowly/smoothly.
I see a lot of guys (in video) just slamming the power open in the first gear that won't loop them off the back rather than running through the lower gears at a power level that keeps the front down. All that torque has to go somewhere.
My rule of thumb is if I can't move the pedals without standing than I'm in too high of a gear. Also I run the largest practical chainring to keep me in the biggest cassette cogs. I don't ever run max throttle in the smaller cogs, I'm not interested in going 40mph.
I'm "only" running ~2.2kw.
 
The pops might come from a bad shifter adjustment, the chain mounting the cog with it's side, then popping into place under pressure.
If it was skipping due to power you would notice it.
 
Check for chain stretch. This is the only time I experience chain slip on my BBS02. When it's time for a new chain AND cassette. Don't bother replacing only one or the other, they will both last much longer if they wear together.

Last time it was actually slipping on the motor chain ring, after about 25,000km the teeth on the Bafang ring were starting to wear and no longer grabbing the chain properly, so I replaced all 3 parts. Chain, front chainring, and cassette.
 
Thats the problem with mid drives: Is that you wear out the driving components faster.
Chain
Rear Cassette/Freewheel
Crank gears
Derailleurs
 
Yeah they do wear out, but I wouldn't say it's that big a deal. I get through a year on a chain/cassette, riding about 1000km a month in a pretty hilly place. The front chainring lasted 3 years before it started to be an issue, and I've never changed the derailleur.

But I don't use PAS, do use the correct gear, and maintain lubrication.
 
Grantmac said:
speedyebikenoob said:
Grantmac said:
Don't start in the wrong gear.
Click to expand...

What do higher powered bikes do though to prevent this? My bike is only about 2400 watts, and I always make sure to start in the lowest gear now, so it's not a problem for me, I'm just kind of curious as to what people with 4k+ watt middrives do.
Click to expand...

They start in the correct gear, or if starting on the flat in a higher gear they add power slowly/smoothly.
I see a lot of guys (in video) just slamming the power open in the first gear that won't loop them off the back rather than running through the lower gears at a power level that keeps the front down. All that torque has to go somewhere.
My rule of thumb is if I can't move the pedals without standing than I'm in too high of a gear. Also I run the largest practical chainring to keep me in the biggest cassette cogs. I don't ever run max throttle in the smaller cogs, I'm not interested in going 40mph.
I'm "only" running ~2.2kw.
Click to expand...

I see, it's the same for me here. My bike can do nearly 40 mph but I never run it even close to that, I only go like 22-23 max for longer distances continuously
 
Tommm said:
The pops might come from a bad shifter adjustment, the chain mounting the cog with it's side, then popping into place under pressure.
If it was skipping due to power you would notice it.
Click to expand...

I regreased my chain actually and now it tends to do it less even if I'm totally lugging the motor, so maybe that too.
 
dustNbone said:
Check for chain stretch. This is the only time I experience chain slip on my BBS02. When it's time for a new chain AND cassette. Don't bother replacing only one or the other, they will both last much longer if they wear together.

Last time it was actually slipping on the motor chain ring, after about 25,000km the teeth on the Bafang ring were starting to wear and no longer grabbing the chain properly, so I replaced all 3 parts. Chain, front chainring, and cassette.
Click to expand...

Damn, where and how do you guys manage to rack up so much mileage on your bikes lol. The chain only has about a hundred miles on it though, I actually regreased it yesterday and it popped a lot less, so maybe it's just not lubricated enough especially since I was going offroading, I've noticed how dirty the chain is though so I'll probably clean it as well.
 
"Only" 2400W is only about 12 times a concerted effort by an average person at the pedals. Maybe 5 times that of an elite athlete.

Such power quickly wears and elongates a chain, which in turn transfers that wear to the sprockets. Once a chain is elongated by 1% or more, it's likely to make noise, fail to shift correctly, or skip under load. (A bike shop will have a tool that can be used to measure chain elongation.)

The best thing you can do to mitigate this accelerated wear is to use bigger sprockets than you would on a pedal-only drive. This reduces the chain's working tension, reduces its angle of articulation, and shares loads among more teeth at any one time.

There are adjustments you can make to your derailleur that might be able to increase the wrap angle of the chain around the rear sprockets. Look for YouTube videos about "B-tension", because if there is too much B-tension, you won't be getting as much wrap around the sprockets as you would with proper adjustment. Also if you have a bike with horizontal dropouts, sliding the rear axle all the way back will increase wrap and reduce the opportunity for the chain to skip.

There are other factors, like chain tension/length, derailleur adjustment, hanger alignment, and chainline that can all contribute to or promote chain skipping. It might not be a bad idea to consult a seasoned professional bike mechanic for a diagnosis and touch-up.
 
speedyebikenoob said:
Tommm said:
The pops might come from a bad shifter adjustment, the chain mounting the cog with it's side, then popping into place under pressure.
If it was skipping due to power you would notice it.
Click to expand...

I regreased my chain actually and now it tends to do it less even if I'm totally lugging the motor, so maybe that too.
Click to expand...

Did you read what I wrote?
 
even with superhuman power levels

sprockets dont wear much

using good fresh chain

using worn stretched chain

sprockets turn to shit

quickly
 
Tommm said:
speedyebikenoob said:
Tommm said:
The pops might come from a bad shifter adjustment, the chain mounting the cog with it's side, then popping into place under pressure.
If it was skipping due to power you would notice it.
Click to expand...

I regreased my chain actually and now it tends to do it less even if I'm totally lugging the motor, so maybe that too.
Click to expand...

Did you read what I wrote?
Click to expand...

Yes I did, I've adjusted the shifter many times, and as I mentioned in my original post, it's not really a problem for me because it never happens when I start off in a lower gear. I just asked out of curiosity.
 
You must log in or register to reply here.

Similar threads

J
Looking for input on chain-sprocket combo for 8kw drivetrain
Replies
4
Views
157
scianiac
S
R
    • Like
L-Faster / Dome Motor 450W Mid-Drive Build
2
Replies
25
Views
3,073
DanGT86
DanGT86
R
    • Like
A critique of mid-drive riding recommendations (and hub drive criticisms)
Replies
15
Views
5,087
Bullfrog
B
A
Outrunner left side mid-drive conversion
Replies
19
Views
1,734
crazy dreamer
C
M
Problems with Votol Em200sp and low acceleration.
Replies
2
Views
801
stan.distortion
stan.distortion
Back
Top