Chainring problem - chain falls off

[erlewine]

Have a specialized bike, Shimano 105 package, triple chainring. I'm having problems with the front chainring - shifting down never seems to be a problem, neither does shifting from 2nd to 3rd gear. However, shifting from 1st gear (smallest ring) to 2nd gear (middle ring) doesnt catch about 30% of the time, and the chain winds up falling right off the rings (usually requires you to get off the bike turn it upside down and manually put it back on).

Is this a common problem? Perhaps its my shifting technique?

 

[Babbar]

Originally posted by erlewine
Have a specialized bike, Shimano 105 package, triple chainring. I'm having problems with the front chainring - shifting down never seems to be a problem, neither does shifting from 2nd to 3rd gear. However, shifting from 1st gear (smallest ring) to 2nd gear (middle ring) doesnt catch about 30% of the time, and the chain winds up falling right off the rings (usually requires you to get off the bike turn it upside down and manually put it back on).

Is this a common problem? Perhaps its my shifting technique?

Sounds like your front derailleur might be bent or, perhaps, the middle ring is not completely true. Check the chain rings, making sure they are evenly spaced and completely true. Check each tooth on the rings to make sure it is not worn.

Then, adjust the front derailleur.

However, it sounds to me like your middle ring might be worn, which means replacing.

 

[boudreaux]

Originally posted by Babbar
Sounds like your front derailleur might be bent or, perhaps, the middle ring is not completely true. Check the chain rings, making sure they are evenly spaced and completely true. Check each tooth on the rings to make sure it is not worn.

Then, adjust the front derailleur.

However, it sounds to me like your middle ring might be worn, which means replacing.

Sounds more to me like the dreailer needs proper adjustment,but a bent ring is a possibility.