Biopace rings and chain suck ?

[squirrelchaser]

Curious to know if anyone has an opinion on weather Biopace rings encourage chain suck ?
I've only got them on one bike and it , er well , sucks .

 

[DoctorRad]

Could it be due to chainring wear, as opposed to their particular shape?

 

[sjcprojects]

I had a Biopace chainset (105) on a road bike for plenty of years with no noticeable issues and I don't recall it being mentioned as an issue when they were introduced back in the day. I suspect wear is more likely, as @DoctorRad suggests...

 

[squirrelchaser]

Could it be due to chainring wear, as opposed to their particular shape?

I'll have a look , thanks .

 

[Imlach]

I've never heard people champion Biopace rings for anything in particular. Modern oval rings are supposedly better but I never understood the concept. I've heard people report chain suck issues with Biopace, but I think it is more likely a result of them being kitted on old bikes that's seen a lot of use and as a result are worn down. As suggested twice in the thread.

I still think they're shit

 

[squirrelchaser]

I've never heard people champion Biopace rings for anything in particular. Modern oval rings are supposedly better but I never understood the concept. I've heard people report chain suck issues with Biopace, but I think it is more likely a result of them being kitted on old bikes that's seen a lot of use and as a result are worn down. As suggested twice in the thread.

I still think they're shit

I knew you weren't a fan somehow .

 

[greencat]

Not a fan either. I used to ride biopace bitd - usually on middle ring and sometimes at an extremely high cadence (once got up to 40mph downhill without spinning out). Biopace always caused knee pain, but near instantly went away with plain circular rings. Wouldn't risk them nowadays.

 

[squirrelchaser]

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

 

[DoctorRad]

Modern oval rings are supposedly better but I never understood the concept.

'Modern' (or correctly oriented) oval rings, in scientific terms, seek to maximise the integral of the product of your instantaneous leg power and the mechanical advantage produced by the chainring. Given that your legs cannot produce constant power during a pedal cycle, a round chainring is not optimal for this purpose.

In practical terms, an oval chainring allows you to move more chain - because of a bigger radius - when you can produce the most power, and gets you through the dead spot of the pedal stroke more quickly by having a smaller radius.

In my experience, the positive effects are most noticeable when climbing off-road, or with luggage or hauling a trailer. After about ten minutes, going back to round rings feels odd and inefficient for a while.

 

[DoctorRad]

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

Probably clutching at straws, but are they 6- or 7-speed-era Biopace? There's a small possibility the chain is too narrow for the rings…