Sakae Oval Tech

Sheldon Brown actually has a few of these chainrings around:

http://www.sheldonbrown.com/harris/chainrings/110.html

John Everett said:

Here's one I've never heard of before. While I'm not in the business,
I work on bikes for friends. The other day I took in a Trek 800
("Comfort" bike?) which has a few funky features. Among them Sakae
Oval Tech Efficiency Plus chain rings.

In all our discussions here on r.b.t about non-round chain rings I
don't recall ever hearing of them before. Were they contemporaneous
with BioPace? What features did they have that made them "superior"
(or just different) from other eccentric rings?

They were contemporaneous with Bio-Pace. I swapped some out several
years ago (also off a Trek 800, IIRC) and put them in a junk box. Then
on a lark this spring I cleaned 'em and put them on Ebay. I was
astounded at the bidding. At the final price they were a cheap set of
rings, but I hadn't thought I could *give* them away.

So for your second question, I suppose somebody finds some value in
them, but I think their main difference with Bio-Pace was patent
infringement avoidance. Mind you, the distinction of Bio-Pace over
prior oval rings was probably to allow a patent in the first place.

Mark Janeba

Mark Janeba said:

They were contemporaneous with Bio-Pace.

Yes, they were a marketing response to Biopace (no hyphen.)

It appeared in the late '80s that Biopace was the wave of the future,
nobody realized that it would be killed by the sneers and ridicule of
the ignorant.

Quoted message said:

So for your second question, I suppose somebody finds some value in
them, but I think their main difference with Bio-Pace was patent
infringement avoidance.

They do the same basic thing, but the Biopace is a subtler shape, while
the Ovaltech and Sugino's "Cycloid" were simple ellipses.

Quoted message said:

Mind you, the distinction of Bio-Pace over
prior oval rings was probably to allow a patent in the first place.

Actually the main difference is in orientation. All of these rings are
oriented at 90 degrees from the classic elliptical rings such as Thetic
and others. Thus they were the _opposite_ of old-style ellipticals,
with round rings occupying a middle ground between the two designs.

It is really a shame that Biopace was laughed off the market by people
who didn't understand it, because it is a real benefit to many riders,
especially those who suffer from knee soreness.

http://sheldonbrown.com/biopace

Sheldon "Biopace" Brown
+--------------------------------------------+
| I’ll be performing in the Summer Revels |
| June 25 & 26, Museum Wharf, Boston |
| http://revels.org |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Ed said:

In article <[email hidden]>, Sheldon Brown says...

Quoted message said:

They do the same basic thing, but the Biopace is a subtler shape, while
the Ovaltech and Sugino's "Cycloid" were simple ellipses.

Biopace is indeed subtile. I fixed up an old bike I had not ridden for several
years and began riding it while continuing to ride my other newer bikes. After
a few months I noticed the chain ring looked odd. I cleaned off the grease on
the ring and discovered the Biopace sticker.

While I cannot feel any difference between Biopace and round chain rings, others
may of course.

When I first got back into cycling in the late 80s, I bought a Trek
1400. After riding it for about six months or so I started riding with
the San Diego CycloVets, and was almost immediately given grief about
my Biopace chain rings. I didn't even know there was anything peculiar
about my chain rings, but upon closer inspection I found they were not
actually round!

Under peer pressure I replaced them with a set of round rings, and
immediately noticed a difference in the feel of the pedal stroke. This
"strangeness" disappeared quite quickly (like during the first ride).
The Biopace rings languish on a shelf in my garage to this day.

jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

Ed said:

In article <[email hidden]>, Sheldon Brown says...

While I cannot feel any difference between Biopace and round chain rings, others
may of course.

I bought a set of Biopace chainrings (52-42) in a used bike shop for
$1. I have many bikes and I chose to put them on one that had a very
tightly spaced 15-23 8 speed cassette, figuring that any benefit would
be most apparent there. I have put about 1000 mile on them and
honestly can't feel any difference.

Tom