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Bike Chain Falling Off
#1
Exclamation 
My chain keeps falling off especially when I transition from 1st to 2nd chain ring. I also feel like I have to use a lot more pressure to shift from 1st to 2nd compared to going from 2nd to 3rd, which just might be me but I thought it was relevant to include. I am not super mechanically inclined so I can't diagnose an issue on my bike like this. Can you please tell me whats the issue and maybe how to fix it?
  Reply
#2
(06-17-2020, 10:28 PM)PIZZAcomboX5 Wrote:  My chain keeps falling off especially when I transition from 1st to 2nd chain ring. I also feel like I have to use a lot more pressure to shift from 1st to 2nd compared to going from 2nd to 3rd, which just might be me but I thought it was relevant to include. I am not super mechanically inclined so I can't diagnose an issue on my bike like this. Can you please tell me whats the issue and maybe how to fix it?

Welcome PIZZAcombo,

What type of bike, how old, and what type of shifters (down tube, bar end, thumb, grip, etc.)? Is your 1st ring in reference to the largest or smallest ring? Has the bike been regularly maintained? Has it been stored being exposed to the elements? These questions will help myself and others to give you some suggestions as to the cause of your problem. I am far from being an expert, but I manage to fix my bike problems on my own given proper tools/equipment. I generally work on +30 year old bikes so bear with me regarding yours if it is newer, but I will help in any way I can.

Take care,
Jesper
"I am become Death, the destroyer of bicycles." NJS
  Reply
#3
(06-22-2020, 04:18 PM)Jesper Wrote:  
(06-17-2020, 10:28 PM)PIZZAcomboX5 Wrote:  My chain keeps falling off especially when I transition from 1st to 2nd chain ring. I also feel like I have to use a lot more pressure to shift from 1st to 2nd compared to going from 2nd to 3rd, which just might be me but I thought it was relevant to include. I am not super mechanically inclined so I can't diagnose an issue on my bike like this. Can you please tell me whats the issue and maybe how to fix it?

Welcome PIZZAcombo,

What type of bike, how old, and what type of shifters (down tube, bar end, thumb, grip, etc.)? Is your 1st ring in reference to the largest or smallest ring? Has the bike been regularly maintained? Has it been stored being exposed to the elements? These questions will help myself and others to give you some suggestions as to the cause of your problem. I am far from being an expert, but I manage to fix my bike problems on my own given proper tools/equipment. I generally work on +30 year old bikes so bear with me regarding yours if it is newer, but I will help in any way I can.

Take care,
Jesper

My bike is a diamondback edgewood hybrid 2016 model, and it is shimano thumb shifters. By 1st ring I mean the smallest ring. I can't say I have maintained it super well, but I usually did maintenance once or twice a year, but I don't use it during the winter and fall, and I don't put it through a lot wear and keep it clean usually. I store it in a basement of sorts with a lot fo other bikes, since I live in an apartment.
  Reply
#4
(06-23-2020, 12:19 AM)PIZZAcomboX5 Wrote:  My bike is a diamondback edgewood hybrid 2016 model, and it is shimano thumb shifters. By 1st ring I mean the smallest ring. I can't say I have maintained it super well, but I usually did maintenance once or twice a year, but I don't use it during the winter and fall, and I don't put it through a lot wear and keep it clean usually. I store it in a basement of sorts with a lot fo other bikes, since I live in an apartment.
Okay "Pizza",
Thanks for the clarification. So if you are shifting from the smallest chainring to the middle ring and the chain "falls off", where does the chain and up? Is it between the small ring and the frame ( that would be odd), or between the largest ( 3rd) ring and the crank arm? I am assuming (remember, l work on very old bikes) that you have indexed shifting, given that fact it could be that the indexing adjustment is not correct, but even that should not send the chain all the way off and past the third ring; l am a bit perplexed! Give me a little more info, I may be over thinking the problem. I am also assuming that the chain is staying put on the rear gear cluster. Do you have the same problem regardless of which rear gear you have engaged?

I'll "stay tuned", and see what presents itself to me. I think that this should be fairly simple in the end given the age of the bike and your riding/maintenance/storage profile.

Jesper
"I am become Death, the destroyer of bicycles." NJS
  Reply
#5
(06-25-2020, 11:57 AM)Jesper Wrote:  
(06-23-2020, 12:19 AM)PIZZAcomboX5 Wrote:  My bike is a diamondback edgewood hybrid 2016 model, and it is shimano thumb shifters. By 1st ring I mean the smallest ring. I can't say I have maintained it super well, but I usually did maintenance once or twice a year, but I don't use it during the winter and fall, and I don't put it through a lot wear and keep it clean usually. I store it in a basement of sorts with a lot fo other bikes, since I live in an apartment.
Okay "Pizza",
Thanks for the clarification. So if you are shifting from the smallest chainring to the middle ring and the chain "falls off", where does the chain and up? Is it between the small ring and the frame ( that would be odd), or between the largest ( 3rd) ring and the crank arm? I am assuming (remember, l work on very old bikes) that you have indexed shifting, given that fact it could be that the indexing adjustment is not correct, but even that should not send the chain all the way off and past the third ring; l am a bit perplexed! Give me a little more info, I may be over thinking the problem. I am also assuming that the chain is staying put on the rear gear cluster. Do you have the same problem regardless of which rear gear you have engaged?

I'll "stay tuned", and see what presents itself to me. I think that this should be fairly simple in the end given the age of the bike and you riding/maintenance/storage profile.

Jesper

Yes sorry I was a bit incorrect in my description, it would usually occur when downshifting from the middle ring to the first ring, causing the chain to end up on the inside of all the gears. I previously described the issues with moving from 1st to 2nd because sometimes when I would shift there would be an incomplete shift, like the derailleur would move but the chain hadn't moved.
  Reply
#6
(06-25-2020, 12:09 PM)PIZZAcomboX5 Wrote:  Yes sorry I was a bit incorrect in my description, it would usually occur when downshifting from the middle ring to the first ring, causing the chain to end up on the inside of all the gears. I previously described the issues with moving from 1st to 2nd because sometimes when I would shift there would be an incomplete shift, like the derailleur would move but the chain hadn't moved.

Okay,
Cool! I'm kind of onboard now. Most front and rear derailleur have "limit adjustment" screws that keep the derailleur chain cage from travelling too far past either the the largest and smallest sprockets on multispeed bikes. If you shift the front derailleur to the smallest ring it should not be allowed to move the cage too far inward. If you adjust the "low limit" screw turning it clockwise, it should slowly move the cage outward. This will need to be set with the rear derailleur on the largest sprocket putting the bike into 1st gear. With the chain in this position you need to adjust the front derailleur cage so that it does not rub the chain when pedalling under load and also does not travel inward too far. When doing this initially just get the cage to a point to where it barely touches the chain on the left side, and then let off the screw (counterclockwise) a little bit (1/4-1/2 a turn) so there is a very slight gap (1/32-1/16") between the chain and cage. You may have to adjust again slightly after riding to see if it has too much or too little clearance when the bike is flexing from pedalling. The same thing should be done for the "high limit" screw with the chain on the largest front sprocket and the smallest rear sprocket putting the bike into 21st gear (if 7 speed rear cluster). Most front indexed shifters have a "micro" stepped index and do not move the derailleur cage over one full ring per "click", but may take 2 or 3 clicks to achieve a full shift to another ring; this is to allow for cage adjustment while shifting the rear derailleur and it keeps the chain from rubbing the front cage if you are staying in the same gear up front. I accomplish the same thing on a friction shifter, but there are no clicks, just get the feel for it and/or move it until the noise stops. Since I am not familiar with the specific design of these shifters/index system, l don't know where the indexing adjustment is located (could be on the shifter, the frame cable stop, the derailleur, or any combination), usually some sort of knurled barrel adjuster. You essentially want to adjust the derailleur to fall over the center of the middle ring on a specific click, and be able to reach the next ring ( lower or higher gear) with an equal amount of clicks. If you are in the front middle ring and shift 2 clicks (or 3, or 4) to get a complete ring change going up then you should also be able to go 2 clicks (or 3, or 4) down to get a full gear going down. If you went from the largest ring to the smallest ring in 8 clicks it just means there are more steps of indexing, which allows for you to fine tune your derailleur cage to avoid chain rub. These adjustments may take a little practice, they don't always work perfectly; especially when parts get swapped out or cable starts to stretch, which may be what was causing the problem in the first place. Someone else may have a better explanation to help you. Let us know what you did to try and solve the problem. Most bike shops would take about 15 min. ( or less) to make these adjustments.
"I am become Death, the destroyer of bicycles." NJS
  Reply
#7
(06-25-2020, 06:05 PM)Jesper Wrote:  
(06-25-2020, 12:09 PM)PIZZAcomboX5 Wrote:  Yes sorry I was a bit incorrect in my description, it would usually occur when downshifting from the middle ring to the first ring, causing the chain to end up on the inside of all the gears. I previously described the issues with moving from 1st to 2nd because sometimes when I would shift there would be an incomplete shift, like the derailleur would move but the chain hadn't moved.

Okay,
Cool! I'm kind of onboard now. Most front and rear derailleur have "limit adjustment" screws that keep the derailleur chain cage from travelling too far past either the the largest and smallest sprockets on multispeed bikes. If you shift the front derailleur to the smallest ring it should not be allowed to move the cage too far inward. If you adjust the "low limit" screw turning it clockwise, it should slowly move the cage outward. This will need to be set with the rear derailleur on the largest sprocket putting the bike into 1st gear. With the chain in this position you need to adjust the front derailleur cage so that it does not rub the chain when pedalling under load and also does not travel inward too far. When doing this initially just get the cage to a point to where it barely touches the chain on the left side, and then let off the screw (counterclockwise) a little bit (1/4-1/2 a turn) so there is a very slight gap (1/32-1/16") between the chain and cage. You may have to adjust again slightly after riding to see if it has too much or too little clearance when the bike is flexing from pedalling. The same thing should be done for the "high limit" screw with the chain on the largest front sprocket and the smallest rear sprocket putting the bike into 21st gear (if 7 speed rear cluster). Most front indexed shifters have a "micro" stepped index and do not move the derailleur cage over one full ring per "click", but may take 2 or 3 clicks to achieve a full shift to another ring; this is to allow for cage adjustment while shifting the rear derailleur and it keeps the chain from rubbing the front cage if you are staying in the same gear up front. I accomplish the same thing on a friction shifter, but there are no clicks, just get the feel for it and/or move it until the noise stops. Since I am not familiar with the specific design of these shifters/index system, l don't know where the indexing adjustment is located (could be on the shifter, the frame cable stop, the derailleur, or any combination), usually some sort of knurled barrel adjuster. You essentially want to adjust the derailleur to fall over the center of the middle ring on a specific click, and be able to reach the next ring ( lower or higher gear) with an equal amount of clicks. If you are in the front middle ring and shift 2 clicks (or 3, or 4) to get a complete ring change going up then you should also be able to go 2 clicks (or 3, or 4) down to get a full gear going down. If you went from the largest ring to the smallest ring in 8 clicks it just means there are more steps of indexing, which allows for you to fine tune your derailleur cage to avoid chain rub. These adjustments may take a little practice, they don't always work perfectly; especially when parts get swapped out or cable starts to stretch, which may be what was causing the problem in the first place. Someone else may have a better explanation to help you. Let us know what you did to try and solve the problem. Most bike shops would take about 15 min. ( or less) to make these adjustments.


Ok thank you so much! Let me try it out and fix it today.
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