Bicycle Mechanics - Badly bent chainwheel (front sprocket), advice please!

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SSkid
03-10-09, 05:27 PM
So the story goes:

I lent my old peugeot to a friend to ride around and he calls me one night telling me something went badly wrong. Turns out the the front sprocket that attaches to the crank is bent... not just a little bent... bent nearly in half. My friend claims he didn't crash it or anything... he was just riding along and next thing he knew, bam! I'm not sure whether to believe him, but I'm wondering if it could have something to do with how the bike was converted to a single speed... like maybe too much pressure put on the chainwheel or something... plus he's a pretty big guy, about 240lb. Any thoughts on the cause, and also, do I need a completely new crank or just a new chainwheel... thanks for any advice! :)

zonatandem
03-10-09, 05:33 PM
Hey the bike stood there leaning against the wall and that stupid chainring bent itself!
operator
03-10-09, 06:24 PM
So the story goes:

I lent my old peugeot to a friend to ride around and he calls me one night telling me something went badly wrong. Turns out the the front sprocket that attaches to the crank is bent... not just a little bent... bent nearly in half. My friend claims he didn't crash it or anything... he was just riding along and next thing he knew, bam! I'm not sure whether to believe him, but I'm wondering if it could have something to do with how the bike was converted to a single speed... like maybe too much pressure put on the chainwheel or something... plus he's a pretty big guy, about 240lb. Any thoughts on the cause, and also, do I need a completely new crank or just a new chainwheel... thanks for any advice! :)

That is entirely possible. Especially if the chainring was spaced out.

Panthers007
03-10-09, 06:49 PM
You need to examine it. At least - he owes you a new chainring.
JohnDThompson
03-10-09, 07:59 PM
So the story goes:

I lent my old peugeot to a friend to ride around and he calls me one night telling me something went badly wrong. Turns out the the front sprocket that attaches to the crank is bent... not just a little bent... bent nearly in half. My friend claims he didn't crash it or anything... he was just riding along and next thing he knew, bam! I'm not sure whether to believe him, but I'm wondering if it could have something to do with how the bike was converted to a single speed... like maybe too much pressure put on the chainwheel or something... plus he's a pretty big guy, about 240lb. Any thoughts on the cause, and also, do I need a completely new crank or just a new chainwheel... thanks for any advice! :)
At a minimum a new chainring, which may be problematic depending on the crank. Check the crank to make sure the spider isn't bent someplace as well.