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Odd chainring actions - seeking opinions(4 posts)

Odd chainring actions - seeking opinionsMcAndrus
Mar 5, 2002 6:11 PM
Well, this is a first. I was out riding my rain bike (a Bianchi Eros) last Sunday for a 55 mile ride. In the last ten miles or so, when I'd stand up on a hill the chain would skip on the cassette.

Hmmm....I said to myself...I just changed the rear derailleur cable a week before. Maybe it's stretching. I'll adjust it when I get home.

When I got home I did a quick resetting of the cable with the bike on the stand, ran it through all nine gears and it was fine. Tonight I'm out riding and the same thing happens! What the hey is going on here?

I look down at the chainring and it's noticeably moving left and right. It's moving back and forth about 1 cm on the downstroke when I stand. This is lateral motion is trying to pull the chain off of the cog and so it skips like it's trying to change gears.

I was close to home so I zipped back into the garage. I checked the crank bolts and the chain ring bolts and all is well. I wiggled the crank arms and they felt solid. I checked the BB with my fingers and it seemed snug (I don't have BB tools. I use an LBS for BBs and headsets). When I ran the gears without a load the chainring runs absolutely straight and true. However, I can see the BB flexing if I put the crankarm under pressure.

So I got out my flashlight and did a close inspection of the chain stays. I saw one line that may (or may not) be a crack near the BB on the inside of the right side chain stay. I want to repeat that it may *not* be a crack, it is so faint it just might be a paint flaw I never noticed.

I'm going to take the bike to the LBS tomorrow but thought I'd see if anyone had any ideas what it might be beside a cracked chainstay?
Your cassette is worn out! Replace it!Rusty McNasty
Mar 6, 2002 5:00 AM
don't forget to replace the chain, too, or the new cassette will wear out in record time.
re: Odd chainring actions - seeking opinionsksfacinelli
Mar 6, 2002 8:47 AM
I had the same problem....it was a cracked frame. I hope not in your case but if it is a quality frame a repair is possible but I would contact the mfg. for a discounted replacement. In 1986 I cracked a entry level Raleigh frame (first bike, never crashed, work hardened the metal)....They sent me one of there team 531 framesets free of charge.

Those were the days.....
Verdict is in - cracked BB shellMcAndrus
Mar 6, 2002 11:51 AM
The LBS guy cleaned and inspected it with a magnifying glass. He said he found a crack in the BB shell. He also said Bianchi is very good about replacing broken frames so he's arranging that now.

I expect I'll be without for a few weeks but it's nice to know Bianchi will stand behind their frame. I guess I'll just have to ride the Giant exclusively until then. And my wife wonders why I have two bikes ;-).

Kind of sad, actually. I've had that frame for seven years. Oh, well. I'm not getting any younger either.