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Discussion Starter · #1 ·
Hello,

I recently fell off my motorcycle and I noticed the chain was too loose. Can that make you fall? I have been riding for so long and the road were I fell... I know it really well because I take it everyday to go home. The road was clean.

What I felt was the back wheel a bit weird before falling. I let someone cross the street and I couldn't brake perfectly, I though it was because it was raining a bit... but then I continued, the wheel went crazy and BAM!

So.. Can the loose chain be the problem?

Thank you in advance for your replies :)
 

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When you say, "the wheel went crazy", I think of either broken spokes or a flat tire.
A loose chain should only affect you if it breaks or comes off the sprocket and jams the wheel.
 

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So.. Can the loose chain be the problem?

Thank you in advance for your replies :)
Doesn't seem possible unless it is so loose it is skipping teeth and I doubt it would stay on very long at that point. You'd have more significant consequences than the back wheel acting weird...
 

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I could see it could contribute, if you are a little jerky on the throttle mayhaps?

-BK
 

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Aside from locking the wheel, I don't think a chain can make you fall. Sounds like you lost traction, then the tire suddenly gained traction and threw you off.
 

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Is it possible you ended up on painted lines on the road? With a little rain they become extremely slick which could cause this "wheel went crazy" as you state. That condition, rain on painted surface, can put you down faster than you can blink. Just a thought. I honestly doubt the chain had anything to do with it but wouldn't rule it out completely.
 

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Discussion Starter · #8 ·
Thank you for your answer. If the problem was the traction, does it mean it was possible to avoid the falling ?
 

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Discussion Starter · #9 ·
Is it possible you ended up on painted lines on the road? With a little rain they become extremely slick which could cause this "wheel went crazy" as you state. That condition, rain on painted surface, can put you down faster than you can blink. Just a thought. I honestly doubt the chain had anything to do with it but wouldn't rule it out completely.
There were no painted lines on the road.. I send you the exact location where it happened: Rue de la Gare 4-14, 2014 Milvignes (I can't post links yet)

Those lines are not there anymore, the road is clean and the "wheel got crazy" just before those round, metallic things (I don't remember the name).
 

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Discussion Starter · #10 ·
Doesn't seem possible unless it is so loose it is skipping teeth and I doubt it would stay on very long at that point. You'd have more significant consequences than the back wheel acting weird...
Is it possible that it skipped a teeth and got back to its place?
 

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There were no painted lines on the road.. I send you the exact location where it happened: Rue de la Gare 4-14, 2014 Milvignes (I can't post links yet)

Those lines are not there anymore, the road is clean and the "wheel got crazy" just before those round, metallic things (I don't remember the name).
Is it possible that it skipped a teeth and got back to its place?
Looks like you have a lot of things going on that could contribute to problems. And yes, you could jump teeth and it now look fine as if nothing happened. Except for tips of sprocket teeth might show signs of jumping. But it would have to be a very loose chain to do that and as a seasoned rider it's doubtful you allowed the chain to get that far out of adjustment. I'm having trouble picturing what a wheel gone crazy is though. In my mind that's like a tank slapper where the wheel goes stop to stop repeatedly. The only other thing I can think of is if you are running on bald or nearly bald tires where they lost traction and you then chopped the throttle. That can lead to all kinds of crazy.
 

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Is it possible that it skipped a teeth and got back to its place?
Yes, it is possible and, as Hog noted, there are probably marks on the sprocket if it did so.

I think it is much more likely that it would cause the wheel to move suddenly as the slack in the chain gets taken up by use of the throttle or brake.
 
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Hello,

I recently fell off my motorcycle and I noticed the chain was too loose. Can that make you fall?
Short answer: no.

Why is the chain loose? Lack of maintenance? Worn out?

What I felt was the back wheel a bit weird before falling.
I'm assuming "weird" means a skid (loss of traction).

The tyre will only skid if the force you apply exceeds the grip available. This always
holds true, even if you are riding on ice or spilled oil.

I let someone cross the street and I couldn't brake perfectly, I though it was because it was raining a bit... but then I continued, the wheel went crazy and BAM!
Light rain after a long dry spell can leave a very slippy surface, much worse than
heavy rain. As others have said, painted lines can be slippy when wet. Wide strips
of tar banding can be very dangerous in wet or extremely hot weather. Metal
manhole covers are very slippy when wet and are often placed in the middle
of the lane.

So.. Can the loose chain be the problem?
Probably not in this case, although jerky/snatchy transmission can make it
more difficult to control the bike in turns and roundabouts.

Rue de la Gare 4-14, 2014 Milvignes
https://goo.gl/maps/QWdFy6YXbSriapMeA

Rue de la Gare seems to be fairly steep with a pedestrian
crossing at the bottom of the hill. Were you travelling east (downhill)?

If the problem was the traction, does it mean it was possible to avoid the falling ?
Yes. Given enough time, it is possible to avoid almost any situation. Better observation
might give you an extra second or two of braking time. Better braking technique may have allowed
you to stop safely. Safety features like ABS and traction control can also help you to
stay in control when road conditions are difficult.

Look after basic maintenance. Check/adjust that chain and replace it if necessary. Check tyre
condition and pressure regularly. Make sure your brakes are in good order........

I'm glad you seem to be ok after your incident. The fact that you are trying to figure out
what happened suggests that you have learned from the experience :thumbsup:

Roadcraft. Motorcycle Roadcraft illustrations. Motorcycle Roadcraft illustrations
 

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Along with everything else stated as being slippery. An old tire is also more slippery than a newer one (especially on a wet road). A tire over 5 years old should be replaced even if it has plenty of tread. There is a 4 digit date code on the side wall of the tire. First 2 digits indicating what week of the year it was manufactured, and the last 2 digits indicating the year it was manufactured. Example a tire manufactured today would have a date code of 4119. I think they do this world wide, but I may be mistaking and possibly just an American code.

Also chains will eventually stretch beyond safe use. They can be measured on a 20 link segment, but I don't know what the specs on your particular chain would be. You may want to consider getting a new chain and both sprockets replaced.
 

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I think the loose chain may only be a contributing factor, at most. The wet road, tire condition, braking, I think you just had the right combination of factors that, if one factor was missing, this would have been a non-incident.

Don't forget what happened, (it may come you one day when you're not thinking about it), just repair any parts that may have been damaged and bring maintenance up to date.

A couple accidents I had, it didn't come to me for days what I had did wrong, but one thing was certain, it was something I did. Pride is a little hurt, but in a one vehicle accident, its the operator.

Was you daydreaming? :)
 

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I would like to know more about the condition of the chain. It was loose, but how loose. When was the last time it was oiled. Links can jamb with no oil. But if the chain jammed, there would be a skid mark on the road, as the wheel would not be turning. Too the chain would probably stay in its jammed position, and there would be marks on the part that it jammed against. Further, pulling in the clutch would not disengage the rear wheel. An inspection of the bike would reveal some info.

UK
 

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Discussion Starter · #17 ·
I think the loose chain may only be a contributing factor, at most. The wet road, tire condition, braking, I think you just had the right combination of factors that, if one factor was missing, this would have been a non-incident.

Don't forget what happened, (it may come you one day when you're not thinking about it), just repair any parts that may have been damaged and bring maintenance up to date.

A couple accidents I had, it didn't come to me for days what I had did wrong, but one thing was certain, it was something I did. Pride is a little hurt, but in a one vehicle accident, its the operator.

Was you daydreaming? :)
I would like to know more about the condition of the chain. It was loose, but how loose. When was the last time it was oiled. Links can jamb with no oil. But if the chain jammed, there would be a skid mark on the road, as the wheel would not be turning. Too the chain would probably stay in its jammed position, and there would be marks on the part that it jammed against. Further, pulling in the clutch would not disengage the rear wheel. An inspection of the bike would reveal some info.

UK
Along with everything else stated as being slippery. An old tire is also more slippery than a newer one (especially on a wet road). A tire over 5 years old should be replaced even if it has plenty of tread. There is a 4 digit date code on the side wall of the tire. First 2 digits indicating what week of the year it was manufactured, and the last 2 digits indicating the year it was manufactured. Example a tire manufactured today would have a date code of 4119. I think they do this world wide, but I may be mistaking and possibly just an American code.

Also chains will eventually stretch beyond safe use. They can be measured on a 20 link segment, but I don't know what the specs on your particular chain would be. You may want to consider getting a new chain and both sprockets replaced.

Thank you for your replies.

1) Here is a couple more info : the tires are 11 months old and still in good condition.

2) The chain was really loose, here is a video : dropbox (dot) com/s/2ta3rhmfay4bgi6/Video%2011-10-19%2013%2004%2013.mov?dl=0 (I can't post links yet). We took this video right after the accident.

3) When I said the rear wheel was "going crazy", what I meant was I felt the wheel blocked or slipped and the motorcycle started "jumping". I felt it a first time in an intersection; I stopped to let someone pass and I felt the rear wheel slipping. I don't know how to explain it, like it was "dancing" on the road for 1 sec. It happened again at a crossing, and then in that turn where I fell. This last time, it was more than just 1 sec, plus with the angled position of the bike in the turn, it resulted in a fall. So, in short, it happened when I was stopping and turning left (didn't feel it turning right).

4) The bike was supposed to be all ok, it had just passed the yearly exam 2 weeks before and they were supposed to check everything so that it is road-ready.

5) I honestly don't think it has anything to do with the condition of the road. It rains all the time here, I am used to it. And, due to all the rain, the roads are never too dirty. Also, there are no painted lines or anything in that turn.

6) After the accident, I brought the bike to the garage and the guy confirmed the chain was way loose and it could have dis-aligned from the sprockets due to the speed (~40km/h) and the angle of the turn (I was going down the road, not up). It didn't get totally out of the sprocket though, it just dis-aligned for a moment and then went back in normal.
 

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Sounds like the chain was jumping across the sprocket. You don't show your location but if your yearly inspection is like most, the chain and sprocket is not part o it. My inspection I got in June included nothing. The guy didn't even look at the bike. I'm ok with it because I do look at the bike and keep an eye on things. And this is another reason I went with a shaft drive bike. No chain.
 

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I have seen in extreme cases where a chain is so loose that when engine braking the chain skips over one of the sprockets. This will act like a dance, and make normal braking feel weird too. Another thing to look for which I have not seen posted here, is make sure your axle is TIGHT. A loose axle will cause the wheel to float in the swing arm and cause the “dance” issues when cornering (ie not want to turn one way but will easily turn the other) and can also cause the rear to shimmy kinda like a tank slapper but from the rear. Hopefully the mechanic you brought it too will get you safely back on the road.

Dominic.
 

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Another thing to look for which I have not seen posted here, is make sure your axle is TIGHT. A loose axle will cause the wheel to float in the swing arm and cause the “dance” issues when cornering (ie not want to turn one way but will easily turn the other) and can also cause the rear to shimmy kinda like a tank slapper but from the rear.
Interesting and good info! Given the symptoms described, that sounds like the most likely cause.

I hope OP will let us know if the cause is found!
 
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