What ever happened to oliptical chainwheels?

[Ray Haynes]

I suspect a mildly eggshaped 52 chainwheel with longer cranks would be a great thing on a recumbent. Anybody have an opinion or experience with same?

My wfe and I are thoughly enjoying our new EVOX's. Her 140 (the low end version) has 175 cranks and is noticably more responsive than my aluminum LE with 170's)...at twice the $400.00 price tag. I hate not being able to keep up with her. Help R.H.

 

[alienator]

I suspect a mildly eggshaped 52 chainwheel with longer cranks would be a great thing on a recumbent. Anybody have an opinion or experience with same?

My wfe and I are thoughly enjoying our new EVOX's. Her 140 (the low end version) has 175 cranks and is noticably more responsive than my aluminum LE with 170's)...at twice the $400.00 price tag. I hate not being able to keep up with her. Help R.H.

I think they died out a few minutes after the proof-reader chastised the engineer who wrote "oliptical" instead of "elliptical."

 

[Ray Haynes]

I think they died out a few minutes after the proof-reader chastised the engineer who wrote "oliptical" instead of "elliptical."

You are quite write, sorrie about that...I was away alot in graid skool.
OK.. so do they work? R.

 

[daveryanwyoming]

I suspect a mildly eggshaped 52 chainwheel with longer cranks would be a great thing on a recumbent. Anybody have an opinion or experience with same?

Check out Q-Rings by Rotor Cranks: http://www.rotorcranksusa.com/s1-q-rings.shtml and keep an eye on the ongoing Q-Rings testing thread in the power forum.

I first saw them on a bent this summer. The rider of course swore by them and insisted they were nothing like the old Shimano Biopace cranks. I wasn't convinced but I'll hold judgement till some of the folks here put them through their paces.

-Dave

 

[daveryanwyoming]

P.S. You might want to trademark that "Oliptical" thing as well as register "Oliptical.com" seems like a slam dunk for starting your own line of eccentric rings

 

[Ray Haynes]

Dave,
Thank you very much..good reference..good story...I'm going to give it a go.
My 68 year old knees will love you I'm sure.
Even at specialty prices, kept in prosective, the bicycle is still is a very low cost rec vehiclle . Ray

 

[Paulie-AU]

I saw recently on cycling news that one of the top pro's use the new ones on his bike.

The difference from biopace is that they actually increase the load at the most powerful part of the stroke and reduce at the lowest as opposed to reducing load during the most powerful part of the stroke with the goal of getting even power.

 

[bobbyOCR]

I have a 42t biopace ring on my fixie. It works like its meant to, if rotated 72 degrees. It is very interesting, it accelerates faster at lower cadences and when sprinting.

 

[hd reynolds]

You are quite write, sorrie about that...I was away alot in graid skool.
OK.. so do they work? R.

write and graid skool won't do much with the spelling teacher either. Anyways, elliptical chainrings are back and with a vengance in that they put biopace chainrings to shame. Bobby Julich uses radically elliptic chainrings on mountain time trials and Landis campaigned one in the U.S. as well as during his infamous 2006 tdf.

 

[531Aussie]

jee, no-one's posted the Cycling News link yet?

http://www.cyclingnews.com/tech/2005/probikes/?id=julich_csc_cervelo

 

[Slugster438]

Check out Q-Rings by Rotor Cranks: http://www.rotorcranksusa.com/s1-q-rings.shtml and keep an eye on the ongoing Q-Rings testing thread in the power forum.

I first saw them on a bent this summer. The rider of course swore by them and insisted they were nothing like the old Shimano Biopace cranks. I wasn't convinced but I'll hold judgement till some of the folks here put them through their paces.

-Dave

There's at least five companies making non-round chainrings available in the US right now, all using different shapes. Rotors are double-symmetrical ovals; others are "rising rate" ("Nautilus" or American-football shaped, with only one axis of symmetry) or rounded parallelograms. There's at least one other company that drills multiple sets of holes so that you can adjust the positioning of the cycloid engagement at closer intervals than 72 degrees.

All are rather expensive, approaching at least $200 for a set of double and $250+ for a set of triple rings. A couple of the companies are basically custom-service machine shops turning out high-end track and TT bike parts, where (for a fee $$$) they will do any shape you can make a CAD file of.

And those five I have seen don't even include BioPace, because Shimano no longer makes them, though you can find NOS examples on the auction sites from time to time.

Most recumbent riders turn to nonround chainrings to help with knee pain. For more power, they tend to mount shorter cranks (155-150mm).

I may try the Rotors soon, and yes, they'll be on a recumbent bike. On a recumbent, your feet accellerate too fast around the "top" and "bottom" portions of the crank cycle (when the crank arms are roughly horizontal, on a recumbent) and this tends to lead to knee pain. Non-round chainrings are said to help prevent the effect.
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