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Chain breaking...

PortnoyPortnoy Posts: 175
edited June 2007 in Road general
I read Sheldon Brown's article on fixed wheel bikes and one of his warnings is that if the chain snaps it can somehow wrap around the rear sprocket causing the back wheel to lock, leading to potential disaster.

However, I've mentioned this to a few people and they say it's nonsense. anyone have any experience of this?

Posts

  • I did have a problem today but it may be my fault. I am new to the fixed wheel generally using the single speed option (I have a fixed/single speed flip flop) for my commute but I went for a 30 mile spin today using the fixed option. I was getting on well and really enjoying it but coming downhill trying not to use the brakes just my pedals the chain jumped off the sprocket and wrapped around it locking the wheel scraping the frame and damaging the chain so that I needed to lose a link to get home. As I said it might be my inexperience. I will also post on the fixed topic.
  • Tom753Tom753 Posts: 737
    I would say if a chain broke the result would be unpredictable, but as the sprocket will continue to spin, it's probable that the chain will wrap around the sprocket or axle to some extent and lock up the wheel.

    Anyway it's not something I'd worry about as long as you keep your chain well maintained, chains usually break because they haven't been joined properly or they're worn out, not because they're not strong enough.

    Also chains shouldn't come off either, if it does then it's too loose!

    <font color="black"><div align="right"><i><font size="1"><font face="Comic Sans MS"> My fixed bike </font id="Comic Sans MS"></font id="size1"></i></div id="right"></font id="black">
  • hazeiihazeii Posts: 233
    Pretty unlikely to have a problem if the chain breaks; on the other hand if it falls off the front ring life can get interesting.
  • CanriderCanrider Posts: 2,253
    It's not nonsense, but a) should be quite rare an even compared to, for example, the chain unshipping due to being too slack, b) locking the rear wheel will make you skid but it's nowhere near as bad as locking the front wheel.

    Not something I worried about beyond my first two weeks of riding fixed.

    "We will never win until the oil runs out or they invent hover cars - but then they may land on us." -- lardarse rider
    "We will never win until the oil runs out or they invent hover cars - but then they may land on us." -- lardarse rider
  • SpoodSpood Posts: 8
    I had a chain jump on me a few years ago. I was using my fixed on a club ride and didn't notice that the rear wheel had crept forward slightly. Until that is, I was going downhil and doing about 32mph, which on a 66 inch is a fair few rpm. The chain came off and after some interesting noises wrapped itself around the rear sprocket locking up the rear wheel.

    The bike skidded for about 30 yards before it came to a stop. To everyones amazement I didn't come off and the rear tyre didn't blow either. Great save were words of praise from quite a few!

    After some roadside puling and tugging we managed to free the chain which allowed me to continue on the ride. There were a couple of teeth missing from the front chainring (Alu) and a tooth missing from the rear sprocket. Also the rear hub had been marked and the rear chainstay on the frame. All-in-all a bit of a mess!

    I was advised by some that one way to ensure this doesn't happen again is to remove the lockring. The theory is that if the rear locks up then the sprocket should unscrew itself with the rear wheel becoming free to spin. I am not too sure that this is good advice and I therefore didn't take it - Fom that day I simply ensure that I check the chain tension every time I ride.
  • SpoodSpood Posts: 8
    I had a chain jump on me a few years ago. I was using my fixed on a club ride and didn't notice that the rear wheel had crept forward slightly. Until that is, I was going downhil and doing about 32mph, which on a 66 inch is a fair few rpm. The chain came off and after some interesting noises wrapped itself around the rear sprocket locking up the rear wheel.

    The bike skidded for about 30 yards before it came to a stop. To everyones amazement I didn't come off and the rear tyre didn't blow either. Great save were words of praise from quite a few!

    After some roadside puling and tugging we managed to free the chain which allowed me to continue on the ride. There were a couple of teeth missing from the front chainring (Alu) and a tooth missing from the rear sprocket. Also the rear hub had been marked and the rear chainstay on the frame. All-in-all a bit of a mess!

    I was advised by some that one way to ensure this doesn't happen again is to remove the lockring. The theory is that if the rear locks up then the sprocket should unscrew itself with the rear wheel becoming free to spin. I am not too sure that this is good advice and I therefore didn't take it - Fom that day I simply ensure that I check the chain tension every time I ride.
  • several of my local touring club have ridden fixed every winter for over 25 years.none can recall a fixed chain breaking, though there have been at least 9 geared chains snap in the last 3 or 4 years. it does happen but it's not an everyday occurance.
  • hazeiihazeii Posts: 233
    It's easy to snap a chain by shifting under power, due to the twisting forces (which is operator error in my book). But seeing how chains don't snap when stalling in a full-force MTB climb (20T front ring and a horrible chainline to the inner rear sprocket) they're not going to snap on a 48T fixed with a perfect chainline unless there's something wrong.
  • smiorgansmiorgan Posts: 195
    Hah!

    On the commute this morning I took it easy - something wasn't quite right, the chain was slacker than usual (but just good enough), and occasionally creaked. "Damn axle creep, I'll see to it at work" I thought.

    Well, I finish my commute going up Steventon Hill, followed by a flat bit on the fast road outside work. Got the bike to the bike sheds and found out why the chain was slack. One of the links was stretched and just on the limit of snapping, probably where I broke the chain to get it off for cleaning a while back and did a bad job of joining it back again. Glad I spotted it at work instead of spinning down the same hill on the way back. (Also glad I have spare links and a chain tool)
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