Chain keep falling off the crank - Giant Explore E3 - 2019

new_ebiker

Member
Not sure what’s going on with my bike, but my chain is keep coming off as soon as I start peddle

I tried to move the crank with my hands, it’s fine when I am not on the bike. However when I get on the bike, and start peddling, the chain will fall off from the crank....

I tried everything, this never happened to me with my road bike.
 

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Mtl_Biker

Active Member
Not sure what’s going on with my bike, but my chain is keep coming off as soon as I start peddle

I tried to move the crank with my hands, it’s fine when I am not on the bike. However when I get on the bike, and start peddling, the chain will fall off from the crank....

I tried everything, this never happened to me with my road bike.
Strange! And especially strange on the photo you supplied... the chain looks like it's so loose that it's come right over the pedal.

Is this the original chain? When you say it's fine when you're not on the bike, do you mean when the bike is just sitting there :) or when up on a bike stand and you're cranking the pedals? If the bike's on the ground I doubt very much if you could pedal it enough to see if the chain is being directed over the chain ring. I would suspect the front derailleur is out of adjustment. Do you have a bike stand?
 

new_ebiker

Member
Hi MTL_Biker. The E+3 doesnt have a front derailleur, just the 9 spd Deore in the back.

It’s on the original chain, approximately 2000km (based on 26 battery charge cycles, since my model doesn’t have the computer that logs the lifetime KMs)
 

Mtl_Biker

Active Member
Hi MTL_Biker. The E+3 doesnt have a front derailleur, just the 9 spd Deore in the back.

It’s on the original chain, approximately 2000km (based on 26 battery charge cycles, since my model doesn’t have the computer that logs the lifetime KMs)
Original chain... I was hoping you'd replaced the chain with perhaps one a few links too long. Chain stretch? I kinda doubt it could be that bad. You didn't answer if you have a bike stand or not. I'd get the bike up on a stand so that you could turn the cranks quickly by hand and try shifting gears... I wonder if the problem is happening when you are at an extreme gear at the rear? Have you been able to pinpoint when exactly the chain comes off the ring?
 

new_ebiker

Member
Original chain... I was hoping you'd replaced the chain with perhaps one a few links too long. Chain stretch? I kinda doubt it could be that bad. You didn't answer if you have a bike stand or not. I'd get the bike up on a stand so that you could turn the cranks quickly by hand and try shifting gears... I wonder if the problem is happening when you are at an extreme gear at the rear? Have you been able to pinpoint when exactly the chain comes off the ring?

I do have a bike stand. it happened this morning on my way to work, and i decided to head back home after this. On my way home, it just keeps popping up (less then 3km)

oh, i also notice something very strange. Even if i m coasting, the chain is still moving forward. I don’t recall the chain moving when i just coast

i am about to get off work, will probably take a look later tonight.

thanks everyone for their valuable inputs.
 

CityExplorer

Well-Known Member
I was thinking it might be chain tension adjustment, but if the chain is moving forward when your coasting then that there is an indication the rear wheel is not torqued right, other rear component assembly issue, or wheel issue. I think you are on to the problem now, good luck.
 

new_ebiker

Member
I was thinking it might be chain tension adjustment, but if the chain is moving forward when your coasting then that there is an indication the rear wheel is not torqued right, other rear component assembly issue, or wheel issue. I think you are on to the problem now, good luck.

i think you are right...

this is how it happened. I went over a bump, i heard my pannier flapped against something. It turns out only one of the two hooks was attached my my rear rack, i suspect it misalign the rear derailleur when it flagged and hit it....

should i bring this to a bike shop. I feel like this is beyond my DIY skill level.... I only able to successfully changed chain before, and adjust the + - limiting screws
 

CityExplorer

Well-Known Member
i think you are right...

this is how it happened. I went over a bump, i heard my pannier flapped against something. It turns out only one of the two hooks was attached my my rear rack, i suspect it misalign the rear derailleur when it flagged and hit it....

should i bring this to a bike shop. I feel like this is beyond my DIY skill level.... I only able to successfully changed chain before, and adjust the + - limiting screws
I don’t know for sure, i’m not much of a bike mechanic yet. Generally though it is a very good idea to bring a new bike to a shop to check everything. They can also help size the bike for you, seat position, forward/reverse handle bar position, etc.
 

new_ebiker

Member
I took it to my lbs, and paid for a tune-up. everything is working fine now. I mentioned about the creaking notice, the guy said it might be due to the bottom bracket, which he see some movement. however, he said i ll have to bring back to a authorized giant dealer for replacing the bottom bracket.

anyone had to replace their bottom bracket yet?
 

Mtl_Biker

Active Member
I took it to my lbs, and paid for a tune-up. everything is working fine now. I mentioned about the creaking notice, the guy said it might be due to the bottom bracket, which he see some movement. however, he said i ll have to bring back to a authorized giant dealer for replacing the bottom bracket.

anyone had to replace their bottom bracket yet?
But what was the problem? What did the guy adjust?

And as far as the creaking, many of us have had it, but at least in my case just tightening everything up solved it.
 

Sierratim

Well-Known Member
I took it to my lbs, and paid for a tune-up. everything is working fine now. I mentioned about the creaking notice, the guy said it might be due to the bottom bracket, which he see some movement. however, he said i ll have to bring back to a authorized giant dealer for replacing the bottom bracket.

anyone had to replace their bottom bracket yet?
Glad the tune-up resolved your chain drop issue. How often had you been cleaning and lubricating your chain?

For mech bikes and hub motor drive ebikes, replacing the bottom bracket is fairly straight forward and a routine part of long term maintenance. With that said your bike has the Yamaha mid-drive motor, does it not? The function of the bottom bracket (connecting the cranks to the frame) is integrated into the motor bearings. A Giant dealer would be best suited to take a look at this to see if your motor needs any adjustments, but with your mileage I wouldn't expect anything major.

BTW - Other mid-drive ebike owners, like myself, are reporting that the extra strain on the chain is requiring chain replacements as often as every 1,000 miles depending on riding conditions. Something to think about...😎
 

rich c

Well-Known Member
Glad the tune-up resolved your chain drop issue. How often had you been cleaning and lubricating your chain?

For mech bikes and hub motor drive ebikes, replacing the bottom bracket is fairly straight forward and a routine part of long term maintenance. With that said your bike has the Yamaha mid-drive motor, does it not? The function of the bottom bracket (connecting the cranks to the frame) is integrated into the motor bearings. A Giant dealer would be best suited to take a look at this to see if your motor needs any adjustments, but with your mileage I wouldn't expect anything major.

BTW - Other mid-drive ebike owners, like myself, are reporting that the extra strain on the chain is requiring chain replacements as often as every 1,000 miles depending on riding conditions. Something to think about...😎
I got 2,500 miles on each of my two Bosch powered Haibikes. One is at 4,200 now, may have to change that chain again before winter. Still on original cassettes. It's not a universal law that everyone destroys chains on their mid drives.
 

new_ebiker

Member
But what was the problem? What did the guy adjust?

And as far as the creaking, many of us have had it, but at least in my case just tightening everything up solved it.

I m not sure to be honest, the place is packed. Usually i get to chit chat with the owner a little bit, but there’s a line up of people getting their bike repair.

I was lucky he’s able to do everything on the same day. I suspect it’s my MEC world tour Pannier, because the lower part (Red circled) that keep the bag from flapping is broken. The chain pop right out when i went through a bigish curve, and i also heard the pannier flapped against something. I suspect the pannier dislocated the rear derailleur somehow.

I remember, i tried to get it fixed in a hurry as I was on my way to work. I was able to get the chain back on the crank, but as soon as I pedal, it pop out again. Eventually after a few tries, the chain just all twisted up so I had to go back home.
 

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