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Crash investigation help!(3 posts)

Crash investigation help!niteschaos
Jun 23, 2002 8:51 AM
I was going out on a long ride yesterday on the rolling hill terrian around my house. As I encountered a short but moderately steep hill about one mile into my ride I decided to just blast up it be getting out of the saddle. I was in my 42/17 gears (I run a triple). There wasn't any noise (like from derailer interference) or signs of slack. Well about my third stroke up the slope it felts as if the chain broke!! It happened so quickly that I went from standing on the pedals to skidding along the pavement at 20mph with no memory of the fall. When everything stopped moving I looked at the chain to find it intact, but it had somehow jumped from my middle chainring to the frame, completely skipping my 30T chainring.

I was wondering if anyone else has ever had this happen to them before. I have a chip in my elbow on no skin on my knee. This is my first crash. I get in between 100 and 120 miles a week, so I am not a stranger to my bike. I'm afraid to get back into training if the chances of this sudden colapse of my geartrain can happen again. I ride a Felt 75 with a full Tiagra group except for my crank, which is some proprietary crank called "Cyclone". Can anyone help me find out what happened? have you seen a freind cranking along up a hill then suddenly whipeout so completely? All I remember was cranking up a hill, then skidding sideways on my elbow and knee. My front derailer was centered over the middle chainring, but my chain was twisted around it and rubbing the frame after the crash. My LBS gave me a new chain by SRAM hopping to fix the problem. Haven't ridden yet, too sore.
Maybe Start Herejromack
Jun 23, 2002 10:25 AM
How many miles on the chain? Check to see if it is stretched. Best to measure it installed on the bike so its under tension.

Also check the rear cog and the crank for tooth wear.

Also check the operation of both the front and rear derailleur. Make sure neither cable got loose.
Possibly an inadvertant shiftLone Gunman
Jun 23, 2002 11:24 AM
I have done something similar without a crash, could have inadvertanly shifted to the little chainring accidently and during the crash shifted back to the center CR. If that happened the initial downshift may have completely missed the little CR dropping the chain and you. Just a thought to the mystery.