Middle chainring problem

[marconfoot]

Hi,

I'm new here so be kind if this problem is common or already answered.

I have a XT crank with new chainrings. The problem is when I shift to the middle chainring and go up a steep hill (lots of force on crank) the chain begins to go up the gear and jam into the FD from the bottom. (I've seen the same thing on a brand new road bike belonging to a friend ). Middle ring is my favorite so I really would appreciate a little help. Thanks

 

[gruppo]

This sounds like "chain suck". You probably need to clean and oil your chain.

 

[Marx SS]

Maybe it's new chainrings on an old(er) chain. This slight difference may catch the chain & pull it around the chainring, enough to give you chain suck.

 

[ireman_1]

When the derailleur isn't properly adjusted (whether that means it's too high-very common or not parallel with the chainrings-even more common) you can have this issue. Also as mentioned earlier, dirty chain/components can lead to this as well. The most common cause I have dealt with is an improperly aligned/adjusted derailleur.

K.

 

[Juba]

Unclean and under lubricated drivetrain components can contribute to chain suck.

Running an old chain on new chain rings can cause this. The teeth on the chain ring might not line up exactly to a stretched chain, causing the chain to not release cleanly off the chainring. Plus, the old chain will greatly accelerate the wear on your chain rings.

A chain that was twisted in anyway might be prone to causing chainsuck as well. Lets say your chain was overshifted and fell off either the small or large chain ring, and you kept pedaling, jamming the chain between the derailleur and chain ring. A chain that has chain suck once might be more prone to having chain suck again as it may become twisted.

Another common cause of chain suck is an improper chainline. If a new bottom bracket was installed, the spindle size may not be correct.

If none of these suggestions help, several companies make anti-chainsuck devices, ask at your local bike shop. This device is a plate that is profiled to match your chain rings, bolted under your chain stays. If the chain starts to be sucked, it hits the plate and falls free again.

Cheers,
Juba

 

[marconfoot]

Thanks for the speedy replies.

I used a new chain and BB (same as spec'd by Specialized)

I'm gonna check for mis-alligned derailleur or bent chain. These are really possible since I'm too cheap to go to mechanics so I do all the assembly myself. I guess the lessons you learn after getting tossed from the bike are the one's you're most likely to remember.

Thanks again

 

[Greg-O]

make sure none of the teeth on the middle chainring are bent as well.