Biopace rings and chain suck ?

[STX-RC]

While they're not new by any means but not unduly worn I'd say .View attachment 777486

They can be worn a specific way that causes chainsuck, maybe due to chainline issues or i don't know what reason exactly, you can see wear better from the opposite side, or even better touch it with your fingers, that will make things clear.
I heard they can be corrected

 

[Oldtat]

Having experienced one of the old On One Inbreds which were made with chainstay that were too flared, are you sure that the biopace oval doesn't take your chainring too close to the chainstay and create suck (which for me manifested as horrible wedging of chain into chainstay)?

 

[Oldtat]

I've explained that terribly. The 'suck' is a chainring/chain interface issue. It's the consequences which the too close chainstay cause....

 

[squirrelchaser]

Having experienced one of the old On One Inbreds which were made with chainstay that were too flared, are you sure that the biopace oval doesn't take your chainring too close to the chainstay and create suck (which for me manifested as horrible wedging of chain into chainstay)?

It does get pretty close as it goes .
Perhaps it's the chain then 'cos the rings are fairly flat not slightly bulged at the base .

 

[STX-RC]

It does get pretty close as it goes .
Perhaps it's the chain then 'cos the rings are fairly flat not slightly bulged at the base .

It seems you have that at all three rings, so it's most likely too close

 

[legrandefromage]

More likely too wide and catching on the outer rings

7/8/9 spd chains all share a similar internal size but the old, old 6 speed chains were almost single speed width

 

[hamster]

They can be worn a specific way that causes chainsuck,

My experience exactly - the teeth take on a slight hook which when added to a worn chain cause it not to release cleanly at the bottom. Usually it's smaller chainrings and in bottom gear, when the chain is most angled to the teeth.

 

[gtturbo]

I always found they were prone to chainsuck more so than other rings. That's why people like Onza brought out the Buzzsaws or Ringle the Antichainsuck device to try and get around the issue. In my head I have it down to the Shimano rings being thicker but cant remember why I think that now.

 

[squirrelchaser]

More likely too wide and catching on the outer rings

7/8/9 spd chains all share a similar internal size but the old, old 6 speed chains were almost single speed width

The chain , too wide ? It's a Sram so unlikely to be pre 7 speed , isn't it ?