Mixing Biopace with normal chainrings

[Titiritero]

I have an old hybrid I'm going to sell. The bike comes with a Deore DX drivetrain, and a Deore Biopace crankset with the usual hybrid gearing of 48-38-28. I'm not a fan of Biopace, mostly because of the looks, since I'm too bad of a cyclist to note oval vs round chainrings while riding.

However, the biggest ring comes with a nice chainring protector that would come in very handy in my commuter, which has a similar Deore crankset, but the mtb version of it, that is, 24-36-46 and not Biopace.

The questions are:
-would it mess the shifting to mix a Biopace big ring with a round middle/small ring?
-will the front derailleur cope fine to shift from a round 36T to an oval 48T ring?

Thanks!

 

[Frankenorange]

There is barely any ovality to the Biopace rings and i will be surprised if it makes any difference in shifting back and forth between a BP ring and a round ring.
I have mixed round rings with Osymetric rings, that are really extreme, and in my experiments, with a friction shifter, they shifted just tickety boo. That was also with a bottom pull mech that had a converter on it ,to make it top pull, so everything was stacked against the mech but it shifted with zero problems.

 

[Lhatch4]

I think my Monster Fat has a mix of chainrings. I need to look at it. I have thumbie shifters on that bike. It shifts fine. Thumb shifters make life easier. I'm not sure if it would work the same using trigger shifters.

 

[MattiThundrrr]

Sheldon had an article on biopace, there's a section on mixing with round rings close to the end

https://www.sheldonbrown.com/biopace.html

 

[Titiritero]

Thanks for all the responses!! And for the Sheldon link! I usually trust a lot what he says, although in this case he is atypically vague. He does not seem to recommend it, but not for technical reasons, but more for the efficiency of it (for those interested, he seems to love biopace, so basically it makes no sense to him not to go full biopace, and if mixing, he thinks biopace is better for low cadence pedaling, ie. the higher gears, but still he'd recommend it for the other rings too).

I guess I'll try it before selling the bike, in case I regret it.

 

[bikeworkshop]

I think my Monster Fat has a mix of chainrings. I need to look at it. I have thumbie shifters on that bike. It shifts fine. Thumb shifters make life easier. I'm not sure if it would work the same using trigger shifters.

And also in turn on the specifics of the shifter and the choice of front derailleur, and then on how fussy the new owner is.

Plenty have done it, and plenty are happy with the result.
The best shifting will be with components matched as intended by shimano.

Most biopace rings had little in the way of pick up pins, cut teeth and ramps, so a more modern index ring ought to work fine
But...tooth count can be crucial, and ovality will affect the distance between the tooth on the ring the chain is leaving, and the tooth on the destination ring, if you see what I mean.

 

[Lhatch4]

If memory serves, I bought the bike with matching round chainrings. The middle chainring was worn along with the chain. I replaced the chain with a new one and grabbed the only middle chainring in my stash that would fit the bolt pattern. It was an off-brand elliptical. It has a top swing XT m730 derailleur. I swapped the period xt trigger shifters for thumbies. Mechanically it works. I can't tell the difference with performance. I think the question is concerning if it will work mechanically. In my experience it will work mechanically.