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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 06-16-08, 04:10 PM   #1
mac
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rear derailleur shifts/slips gears, then front, finally broke chain, walked home :-(

Very rarely have I noticed any shifting/slipping of my derailleurs. However, on my 2nd to last ride, when I was pedaling hard, especially up a mountain, I noticed my rear derailleur kept shifting/slipping. I was so bad I took my bike in for a tune-up.

On my last ride this morning (commute to work), the rear derailler continued to shift/slip on the flats and as I was climbing a mountain the front derailler started to shift/slip as well. Finally, the chain snapped off - I broke one of the links! So I had a 1+ hour walk home to try to think of what the problem would be.

I took it back to the bike shop and they replaced the chain. They suspect that one or more gears/teeth on my rear cassette might be worn. I'm not sure how that would explain the front derailler slipping this morning. If I have time this evening, I'll take my bike for a test ride to see if the new chain fixed my problem or not.

Any suggestions from you guys what it might be?
  • 2005 Cannondale T2000 Touring Bike
  • 2,800+ miles on same chain before it snapped
  • total bike weight ~ 50lbs
  • me < 200 lbs
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Old 06-16-08, 05:48 PM   #2
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I'm not sure how that would explain the front derailler slipping this morning. If I have time this evening, I'll take my bike for a test ride to see if the new chain fixed my problem or not.

Any suggestions from you guys what it might be?[/LIST]
I'd vote the old chain had a jacked-up link. This link was causing the mis-shifts and finally broke.

Now, I'm not too sure what a jacked up link might be. Perhaps a damaged side plate, caused by some sort of impact to it (say chain was in big ring, and you smacked a rock) which damaged a link. Or a pin started working itself out (the pin could catch on parts and cause mis-shifts) and finally broke.

I carry a SRAM Powerlink in my Camelbak to repair busted links on chains. I've replaced three links on trail (all other riders) in my many years of riding.
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Old 06-16-08, 06:27 PM   #3
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Originally Posted by mac View Post
Very rarely have I noticed any shifting/slipping of my derailleurs. However, on my 2nd to last ride, when I was pedaling hard, especially up a mountain, I noticed my rear derailleur kept shifting/slipping. I was so bad I took my bike in for a tune-up.

On my last ride this morning (commute to work), the rear derailler continued to shift/slip on the flats and as I was climbing a mountain the front derailler started to shift/slip as well. Finally, the chain snapped off - I broke one of the links! So I had a 1+ hour walk home to try to think of what the problem would be.

I took it back to the bike shop and they replaced the chain. They suspect that one or more gears/teeth on my rear cassette might be worn. I'm not sure how that would explain the front derailler slipping this morning. If I have time this evening, I'll take my bike for a test ride to see if the new chain fixed my problem or not.

Any suggestions from you guys what it might be?
  • 2005 Cannondale T2000 Touring Bike
  • 2,800+ miles on same chain before it snapped
  • total bike weight ~ 50lbs
  • me < 200 lbs
At your weight and your mileage, probably chain wear. Did you keep the chain to measure for wear? The more worn a chain is the more likely it is to break under load.
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Old 06-18-08, 11:23 PM   #4
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At your weight and your mileage, probably chain wear. Did you keep the chain to measure for wear? The more worn a chain is the more likely it is to break under load.
No, I had my LBS dispose of it. Well I went for a 30-mile ride this evening around the mountains and I think it was just the chain. Only once did I have some gears shift/slip, but I adjusted the cable tension on-the-fly and it went away. Sheesh, I'm glad I wasn't on tour in the middle of nowhere when my chain snapped. How can you tell when your chain is going bad? Once I started having shifting problems the chain snapped within 20 miles.
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Old 06-18-08, 11:27 PM   #5
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My guess would also be a damaged or stiff link.
Maybe the chain had already lost one sideplate and was warning you?
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