Chain falling off front chain ring over bumps

Z

ZAQ

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Feb 22, 2015
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Hi there,

I recently finished installing g a bafang bbso2 on my Diamnond back mission 2. Everything is working great as it helped fly up even steep trails. Problem is on the down hill my chain constantly falls off the front chain ring. I think my chain tension is OK. Yesterday I installed a Third Eye chain watcher but this did not help. Any advice would be greatly appreciated :)
 

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Likely your bike had a front derailleur or chain guide before you converted it. Has that been properly adjusted to the new spacing of the BBS02?

There are 2 things that will make a chain fall off. Poor Tension, and Poor chain alignment. Any time you have a multi gear bike, you will suffer the effects of poor chain alignment, so you need to have a chain guide on the front if you're not running a front derailleur.
 
ZAQ said:
Hi there,

I recently finished installing g a bafang bbso2 on my Diamnond back mission 2. Everything is working great as it helped fly up even steep trails. Problem is on the down hill my chain constantly falls off the front chain ring. I think my chain tension is OK. Yesterday I installed a Third Eye chain watcher but this did not help. Any advice would be greatly appreciated :)
Click to expand...

I had similar problems until I installed the bbS specific 42T bling ring which is a narrow wide chain ring with a large offset that you can get from Em3ev. It fixed my chain line which may have been a contributing factor to chain drop - that it's a narrow wide chain ring probably doesn't hurt either. I also installed a new chain and made sure the length was correct. All these probably helped keep the chain in place.

A chain guide wouldn't be a bad idea either.
 
Ever wondered why there is such a variety of chain guard, guide, bash guard... In the MTB components ?
That is because we need one, and the harder we ride, the better it has to be.

665880d1326342843-noob-chain-guide-question-mrp-lopes-1x9-sc-jackal-2012-01-11-18.18.29.jpg


51Ys5Vf%2BX8L._SY355_.jpg


p4pb5231881.jpg
 
That happened to me all the damn time with the bbs02. the offset of the drive does not help.
 
Needs a guide on the top of the chain for sure. Maybe not one as funky as the poor mans version, but something. Id just put the front derailleur back on, but replace the cable with a short piece of baling wire so you don't need a shifter.

Use the wire to adjust to line up nice with the front ring, and lock it in place by bending it over. This way your derailleur will guide the chain as it rolls onto the front ring. As it rolls on, it needs some help if you are losing the chain all the time. When the chain bounces a lot, it's just rolling off the sprocket.
 
Kiriakos GR said:
dogman dan said:
Needs a guide on the top of the chain for sure. Maybe not one as funky as the poor mans version, but something.
Click to expand...

How about this idea ? ( Greek Patent pending) :lol:
Click to expand...

It needs to be at the seat tube, behind the chain wheel engagement. If it's installed in front like that it will jam or not do anything at all. A chain catcher doesn't touch the chain normally, just stops the chain if it starts coming off.
 
Kiriakos GR said:
The all idea is a long screw and a ball bearing attached over the frame, over the location that the chain would jump out.
The bearing will not touch anything at normal use, when chain is about to pop out the bearing will act as bumper.

With my Tianjin BEWO Mid-drive KIT I do not have such a problem, therefore I am just passing suggestions, possibly usable by some one who has a bit engineering training.
Click to expand...

You don't have that problem because you ride on flat roads with hardly a bump. Try going over rutted snow/ice at 20 - 30 kph or downhill off-road like the OP and I'm pretty sure you'll have issues even with your brand new untested Eastern European chain on your underpowered mid-drive. ;)
 
I just installed my new BBSO2 kit two weeks ago and I installed this on the same day. My chain has not come off yet...
http://www.niagaracycle.com/categories/origin8-ultim8-chain-guide-clamp-mount-31-8-34-9mm-black?gclid=CKXonKXnzsQCFYI_aQodBJIAow
 
Interesting looking idea, which might work as a tensioner, like if you need to alter the height of the chain line to the back. Sometimes you need to do this if a bike is altered a lot.

IMO, the real issue in this case is not holding the chain down, but holding the chain in line with the front chainring. So whatever is done, needs to control the whip of the chain from side to side, just like a front derailleur does.

I'm a bit surprised to learn this is a problem for the bafang, since I thought this issue was more of a problem when you remove the front derailleur, but keep the original double or triple crank. The rings have ramps built into the gear that make shifting to the other ring easier, so they throw the chain very easily with the derailleur gone.

I still say, put the front derailleur back. Or add one if need be, just as a chain guide.
 
Kiriakos GR said:
... Bafang did this KIT for uphill commuting, off road use is out of it specifications.
Click to expand...
:D

Most of us are riding far out of spec.
If we did limit ourselves to what things are made for, we wouldn't need to build our own bikes.
 
MadRhino said:
Most of us are riding far out of spec.
If we did limit ourselves to what things are made for, we wouldn't need to build our own bikes.
Click to expand...
I expect my contraptions horrify him. ;) (and others)
 
amberwolf said:
MadRhino said:
Most of us are riding far out of spec.
If we did limit ourselves to what things are made for, we wouldn't need to build our own bikes.
Click to expand...
I expect my contraptions horrify him. ;) (and others)
Click to expand...

Yep, that one especially. :mrgreen:

file.php
 
Whatever works, works. I never had much problem losing the chain off road, since my beyond spec bike rarely got pedaled. If it just happened once in a blue moon, just removing a link or two solved it.

I had one bike, a city commuter that started throwing the chain a lot after I took off a front derailleur. I just put back the front derailleur, and it stopped happening. It was a large dip in the bike trail that threw the chain every time. Just not pedaling through the dip worked, but it was better in the end to just put the front derailleur back.

Wear? I didn't say put it back so it rubbed all the time. Adjust it, and it won't wear out your chain to have a guide, whether it's a great one like Mad Rhinos, or a beer can bent into a U shape. You just need a thing that rubs as it's almost off the gear, which nudges it back on. If you are throwing a chain constantly, then you need to look at how crooked your chain line is, how worn your chain is, how loose it's tension, etc. Maybe you need to put a spacer under your freewheel, take one out, change chains, whatever.

Guy that started this can easily still be reading. Some just don't want to talk much, or maybe he just made a tensioner from a beer can or a zip tie and is happy. But others can still learn a lot from this discussion.
 
The more suspension travel, and the more sag that you set to ride, the better the chain line need to be kept. Not saying about bushes and branches and rocks. A chain that drives smoothly with even tension, and guided off any wobbling no matter how it's beaten in the trail... It could be 10 yrs old and still driving fine, especially on our bikes that be don't need to pedal very hard. On the other hand, you can kill a new chain in no time with a wrong setup.
 
Kiriakos GR said:
Learning is good if you start trusting the word of engineers...
Click to expand...
Engineers are not geniuses. Geniuses are building what engineers are saying that it can't be done.
 
Kiriakos GR said:
MadRhino said:
Kiriakos GR said:
Learning is good if you start trusting the word of engineers...
Click to expand...
Engineers are not geniuses. Geniuses are building what engineers are saying that it can't be done.
Click to expand...

One single brain is unable to get involved in a complex and admirable project.
Any one who has not receive technical training he will agree with you, because your words makes him feel equal with anyone else.

In the real world, some one will conceive a smart idea which seems profitable as product, and he will invite the best engineers of every specialization, so them to solve the puzzle, electricians included too. :lol:
Click to expand...

It's not your super chain that keeps it from falling off. If you rode hard off road there would probably be an even bigger chance of dropping, as the BEWO has even more (2mm more) offset than the Bafang, at least according to the technical drawing. Off road riding causes the chain to whip up and down, even slapping against the chainstay. It's why trail bikes have guides and clutch derailleurs.
 
Off road with electric assistance bicycle violates all laws of this universe
Click to expand...


Oh my gosh I cant believe my ears. Is this a dream?????

Less longevity, probably; less reliability, sure; beyond mfg design, questionable; violate the laws of the universe wt???????????????????????????????

It is confirmed I am in lala land- beam me up scotty!
 
Kiriakos GR said:


Off road with electric assistance bicycle violates all laws of this universe, starting from electric system and batteries abuse, electronics components abuse, and even down to mechanical issues.
What BEWO and Bafang has to do with that? Both never design a KIT for such conditions.
Neither my super chain is designed for off road use.

Electric bicycle assistance as concept aiming exclusively regular City bicycles and even MTB frames, and this is all.
Any one passing this red line, he is all alone, and does not worth any sympathy from any responsible group of people for his own troubles, issues, and damages that he is facing.

And if you wish to see that in writing you will ... Electric bicycle assistance over BMX bicycles is out of specifications activity, and there is not even one second as warranty time for a product used that way, no matter what is it.
BEWO offer two years warranty and Bafang 28 months, definably some one crashing such KIT over a mountain, he can not claim any warranty plan, and all that he will do, is to come and nag in a forum.

In what I feel victorious is that I managed to compose an electric assistance bicycle by using all latest high-end components from every aspect, and my gain is 7 years reliability, and I am tremendously happy just about that.
Bicycle industry moves ahead, components compatibility changes all the time, I am not the one who will become sponsor of training magicians, neither I will buy bicycle components every few months.
Today lots of grownup returning to bicycles because is considered as cost effective solution.
And cost effective does not translate to an unreliable bicycle with lowest quality dirt cheap parts.
Click to expand...

Sure wish there was something true in that. Here's the Bafang BBS01 warranty PDF if you're interested. Bafang Warranty.
Check page 28-29. There is nothing about off road riding.
 
Presuming the chain jumps off the same side every time, you could just put the derailleur back. Bandaging your alignment issue. If the chain jumps off any side it likes with no pattern emerging, then chain tension is more likely the culprit.

Have you found a low speed 'drop off' point, where you can study the chains movement safely?

Checked the chain travels nicely when you pedal backwards? A stiff set of rear componets will resist a weak derailleur springs efforts to let the slack come back. Many people level off the pedals for a drop, and will backpedal to do so. This makes slack before a fall, if the derailleur tension spring can't pull it in quickly. It is then that alignment issues will really show. As the unsupported chain does a Mexican wave.

Looks like the aftermarket caters well for this. Hopefully well practiced methods will find and fix your problem, but if that fails some pretty iron clad offerings look available.
 
Kiriakos GR said:
Bafang limited warranty does not cover or apply to the following:
1) Damage, failure and/or loss caused by refitting, neglect,
improper maintenance, competition or commercial purpose,
misuse, abuse or accident;


It supposed that some one can understand the easy to be implied restrictions.
Click to expand...
Yep, 2 things to understand there

1- Waranty is for pussies
2- Advice to pussies: Chinese warranty is a joke
 
KGR, open your mind and your heart will follow.

The possibilities are endless and unlimited once you choose to live outside the tiny box you confine yourself to.
 
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