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Snapping chains hurt!

Started by MichaelB · · Last activity · 10 posts · 1,524 views

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Bike Cafe
Published
20 January 2006
Last activity
22 January 2006
Original author
MichaelB
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10
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  1. Well sometimes. I posted a few weeks ago saying I snapped my chain on my knackered bike and then repaired it out of convenience and tightness. Well yesterday the inevitable happened and it snapped again only this time I was accelerating really hard and standing on the pedals.

    I got lucky on this occasion and didn't have an accident but strange as it may sound I was heading over the handle bars when it snapped because somehow the opposite pedal to that being loaded fired me upwards. There were no cars about and I was just starting to accelerate at about 20mph when it happened but it was quite an exciting moment none-the-less.

    Does a chain snapping often result in an accident? I felt like I was close and I have gotten away with murder on bikes. There was one time when the pedal hit the ground, lifted the wheels clean off the ground and when I landed I wobbled the length of our the road with my hands on the handle bar, one leg trailing along the ground and the other leg wedged under the saddle. Quite an impressive site. There were ofcourse the other times where I really hurt myself.

  2. I've never snapped a chain, and I use the SRAM P89R Hollowpin.

    What chain did you use? Are you just a strong fast biker? What's your best top speed in the flats with no wind?

    Mine is 32.9 mph.

  3. JTE83 said:

    I've never snapped a chain, and I use the SRAM P89R Hollowpin.

    What chain did you use? Are you just a strong fast biker? What's your best top speed in the flats with no wind?

    Mine is 32.9 mph.

    I dont use a computer anymore because it became an obsession.

    I dont think its because I am a particularly strong rider because I am basically a little 9 and a half stone wimp!

    I dont know why it kept snapping but it is probably just wear. The chain was a good chain and it amazed me as to how long it was lasting without stretching and slipping. The chains I usually use barely fit on the sprockets when they start slipping and require replacement but this chain never got to that stage. I think thats why it happened because I never replaced it because it never seemed to stretched until it snapped!

  4. i was using a shimano HG-73 (or something like that) i was racing some of the guys in the group up this hill and i had been pushing a big gear as we crested the hill i stood up on the pedals to accellerate and as i did the chain snapped:eek:

    i bounced off my aero bars and over the handle bars, broke 2 ribs , heaps of road rash............but i still rode the 40k home. on the plus side i got out of doing final smester exams at uni and got the average mark for the couse!😄

    i was riding hard when it snaped, i only way 65KG or about 130lbs

  5. Campy went through a few years after 2000 when their chains would open under load. I think these were the first permalink chains. A teammate of mine broke three in one year, and I broke three the same year, always in a sprint or powering up a short hill...under the highest load. He went over the bars when one chain broke, but you can usually control the bike. It's a real wake-up when it happens..."HELL-ohhhhh!!"

    The newer Campy chains don't have this problem.

  6. Since I have Junior Gearing (45x12) my fastest speed to date on the flats was 37 mph. I was spinning out (120+) in a field sprint and I was able to take 4th.

  7. Chain snapping - that get me scared - don't want that to happen at high speed. How long can a chain last before it needs replacement? 10000 miles?

  8. Iron Man said:


    ...i got out of doing final smester exams at uni and got the average mark for the couse!😄

    Funny. I was hospitalised two weeks before my master's finals. I had to have an operation to fix the extra degree of freedom I had given my arm (I think we had a robotics exam concrening degrees of freedom of arms!) and was generally a bit battered , sore and dazed. Well anywho the meanies in uni wouldn't give me my average for that year for my masters (even though it was 84% - 14 above the cut off for my grade) and so now I am a mere BEng whereas my coleagues are now all MEngs. 🙁

    I didn't even get to sit with me mates in the graduation 😉

  9. The thing I have noticed about these chain snapping stories is that you go over your handle bars. Thats what I experienced too; although I never actually went over but nearly did.

    I would have thought the worst thing was the sudden weight transferring to one side of the bike as the pedal got to the bottom of the stroke but that doesn't seems to be the issue.

  10. JTE83 said:

    Chain snapping - that get me scared - don't want that to happen at high speed. How long can a chain last before it needs replacement? 10000 miles?

    We've been using Shimano and SRAM chains and we get about 2000 miles before they need to be replaced. But that's just an average. I've seen a brand new Shimano chain blow out after <800 miles.

    In that case the side plate of one of the links tore away. In hindsight we should have seen that one coming. My friend was getting phantom shifting of about 30 miles before the blowout. The chain failed when she was attacking a hill and out of the saddle. The sudden loss of resistance caused her to go over the bar. She got bruised, torn, and nasty bite from the chain ring.

    Chain life depends a lot on how they're used and maintained. What people call 'chain stretch' has nothing to do with stretching. There's no way on earth that you're going to stretch a chain. First of all you can't generate anywhere near the amount of load that it would take to stretch a chain. Secondly, the teeth on your gears would shred way before the chain.

    What actually happens is that dirt gets into the links and grinds the pins. As the diameter of the pins get smaller the links in the chain can move relative to each other.

    [font='Times New Roman']So clean and lube your chains and they'll last longer. More importantly, a worn chain plays hell with the teeth on your gears. A worn chain will slip forward on the gear tooth and cause excessive wear.[/font]

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