There are a number of elliptical chainrings of different technologies for different purposes. I used to use the Shimano Biopace version on upright bikes and it helped my particular situation, but theyhave disadvantages--the chain tension constantly changes, and unless there is a sufficient spring on the derailer to keep it pulled tight all the time, it can derail under some conditions, and jump off your chainrings, especially on bumpy roads (which we have a lot of around here).
The ones I've had also only fit specific cranks. If you want to use any chainrings on other cranks than those they come with, you'll have to see if they have the same BCD and number of bolts, size of bolt holes, and any offsets will still line your chain up.
I recommend sites like SheldonBrown for bicycle part info, maintenance, etc.
The semi-recumbent ones I use now change all the angles things work at, so those chainrings don't work correctly on them to do the same job, and I just use the round ones now. My joints can't handle the torque they used to anyway, so for me the motors do nearly all the work, and it doesn't make much difference which chainrings I use.
The ones I've had also only fit specific cranks. If you want to use any chainrings on other cranks than those they come with, you'll have to see if they have the same BCD and number of bolts, size of bolt holes, and any offsets will still line your chain up.
I recommend sites like SheldonBrown for bicycle part info, maintenance, etc.
The semi-recumbent ones I use now change all the angles things work at, so those chainrings don't work correctly on them to do the same job, and I just use the round ones now. My joints can't handle the torque they used to anyway, so for me the motors do nearly all the work, and it doesn't make much difference which chainrings I use.
