Bought this old Nishiki Prestige 6 speed road bike that I am restoring for use as my training bike. Anyways, it has this wierd 40 tooth small chain ring (27 inch wheels) that is eliptical. The 52 tooth big chain ring is normal, ie. round. The “feel” of the small chain ring is strange, particularly when climbing at a low cadence. Does anyone know much about this? Why isn’t it still used? Perhaps there were health issues , like maybe knee problems. If so, it’s coming off. thanks, Conrad PS Dumb question…but how do I switch to single spacing when typing out a post?
For the love of god, if you have any respect for your knees at all lose the elliptical chainring.
I have only had 2 knee injuries from cycling. One was caused by poor fit. The other was caused by those infernal “biopace” rings.
Sounds like the Shimano Biopace from years ago. Some people still think they’re the cat’s meow while others hate them. Heed the message about knee pain. Some reports also claim the same with the newer Rotor cranks. Both systems were designed to minimize the “flat spot” in the cranking cycle.
Tom D. still has a set (i think) that he’s posted good things about.
If I remember, about 20 years ago someone made elliptical chain rings to improve efficiency. They didn’t seel well. I don’t know if they worked. Any of you long time bike folks know anything about that?
I used biopace when I first starting cycling in '89 (or there abouts) while finishing uni. At the time I didnt know any better. I believe that they did work slightly better for recreational cyclists at slower cadences. The idea was actually to increase the leverage at the top and bottom of the stroke. The problem was experienced cyclists who were used to high cadences with round chainrings hated them, and recreational riders want to buy what the pro’s use as well (that is why you see people suffering with a 53-39 and 11-21 cassette). Personally I couldnt tell a lot of difference. What I did notice was that the oval chainrings messed up front shifting and caused major chainsuck. Bought round rings 1 year later and never looked back.
KR
This is getting weird. I dig out an old Nishiki and clean it up and within the week, you’re the second guy asking about old Nishiki 6 speeds. Mine has a triple, they’re all round, except the big ring is a 50, the small ring is a 30, and the middle appears to be only 2 less than the big ring, which doesn’t seem to make a lot of sense. Other than that, the bike rides well and shifts smoothly. The derailleurs are Suntour.
When I first started tris in 1985, I had a bike with Biopace (elliptical) big and small rings that I used till 1989. They work great at sub 85 RPM. When I started working on riding at higher RPM like 100 RPM back in 1990, all my roadie friends got me to switch to converntional round rings. I have not gone back, but wonder if Rotorcranks and Biopace rings are different solutions to the problem of minimizing the dead spot.
It is scary to think that the Biopace chainrings came out 20 years ago. It just seems like it was yesterday.
Dev
Thanks for everyones input. Needless to say, they are coming
off the bike.
good lusk training and racing
CS
When I first started tris in 1985, I had a bike with Biopace (elliptical) big and small rings that I used till 1989. They work great at sub 85 RPM. When I started working on riding at higher RPM like 100 RPM back in 1990, all my roadie friends got me to switch to converntional round rings. I have not gone back, but wonder if Rotorcranks and Biopace rings are different solutions to the problem of minimizing the dead spot.
It is scary to think that the Biopace chainrings came out 20 years ago. It just seems like it was yesterday.
Dev
Found some good info from Sheldon Brown concerning the
Shimano Biopace.
Anyone know if Shimano still makes the Biopace HP (for High Performance) chainrings. The orginal Biopace, that I once used were optimized to sub 90 RPM, but the HP had a less pronounced “biopace shape” and Shimano stated that they could be used up to 150 RPM’s. For those of you who were around in the late 80’s racing tris, remember those Centurion ads featuring Dave Scott with his Centurion with biopace rings ? Did Dave ever use them in any of his 6 KONA wins. Perhaps some of you Boulder residents could ask him and post whether he actually ever did or not !
Just got rid of my Schwinn Tempo road bike with Biopace on it. Didn’t bother me at all. But then again I used that bike for touring.
Believe it or not, these rings are still on my road/tri bike. I got the frame second hand in '91 (Raleigh, Reynolds 531), and bought a new 105 groups set then. I have used the bike off and on since then, but consistently in the last two years, including a half ironman in January '04. No knee problems or anything else I could attribute to the biopace.
And yes, I am giving in to progress and getting a new Dual in about a month…I wonder if it will feel faster than my old steed?