SR & Sugino Elliptical chainrings in 74mm, 110mm & 130mm Bolt Circle Diameter (BCD)

On this page:
74mm BCD (Bolt Circle Diameter) Chainrings on this page:
SR (Sakae Ringyo): 28-tooth
Sugino: 28-tooth

110mm BCD (Bolt Circle Diameter) Chainrings on this page:
SR (Sakae Ringyo): 44-tooth

130mm BCD (Bolt Circle Diameter) Chainrings on this page:
SR (Sakae Ringyo): 42-tooth | 52-tooth

We also have a good stock of Shimano Biopace elliptical chainrings posted here.

We do not have an on-line shopping cart at this time. Have any questions or see something you that interests you, please call us: (503) 480-2001

It is thought by a contributor to the Velobase.com site that both the SR and Sugino elliptical chainring productions were licensed by Shimano. So here's an explanaton of the Shimano elliptical chainrings, which also applies to the rings posted below.

Shimano Biopace chainrings brilliantly solve the problems that purely elliptical chain rings present. Sheldon Brown gave an excellent explanation of how Shimano's engineers have taken a flawed century-old idea to create a wonderfully designed and superbly efficient chainring.

"Biopace is a patented non-round chainwheel design made and licensed by Shimano. To a casual glance, Biopace chainwheels resemble elliptical chainwheels, but on closer examination they turn out to be the opposite of the classical elliptical design. The product of extensive research and computer-aided design, Biopace chainwheels have the small radius engaged when the cranks are horizontal, the large when they are vertical. This is because the Biopace design is based on a dynamic analysis of the motion and momentum of moving cranks and legs, unlike the static, geometric analysis that produced classical ellipticals.

"The theory is that during the power stroke, when the cranks are more or less horizontal, you are using the power of your legs to accelerate your feet, which get going quite fast in the lower gear provided for that part of the stroke. The momentum of your feet then carries the pedals through the "dead spot" when the cranks are near vertical. Since the rider doesn't push as hard during the power phase of the stroke, and motion is slower when the leg is changing direction, the Biopace design is gentler on the knees than even round chainwheels."

If you are unsure about what size chainring you need, Wolf Tooth Components has an excellent guide to measuring your rings.

---

74mm BCD (Bolt Circle Diameter) Chainrings:

SR OvalTech 28-tooth, 74mm BCD chainring. Used, $25.00

Side one

Side two

Sugino Cycloid 28-tooth, 74mm BCD chainring. Used

We have two: #1 | #2

Sugino Cycloid 28-tooth, 74mm BCD chainring #1. Used, $25.00

Top side

And the back side of the same ring

Sugino Cycloid 28-tooth, 74mm BCD chainring #2. Used, $25.00

Many hills left in this ring

And here it is turned over.

---

110mm BCD (Bolt Circle Diameter) Chainrings:

SR OvalTech 110mm BCD 44-tooth chainring

We have two: New | Used

SR OvalTech 110mm BCD 44-tooth chainring. New, $25.00

This was removed from a new bike

Side one

And side two

SR OvalTech 110mm BCD 44-tooth chainring. Used, $25.00

In great condition

And just as good flipped over.

---

130mm BCD (Bolt Circle Diameter) Chainrings:

SR OvalTech 130mm BCD 42-tooth chainring. Used

We have two: #1 | #2

SR OvalTech 130mm BCD 42-tooth chainring #1. Used, $25.00

Side one

And side two

SR OvalTech 130mm BCD 42-tooth chainring #2. Used, $25.00

Used, but with lots of miles left in it.

And here's the other side.

SR OvalTech 130mm BCD 52-tooth chainring. Used, $25.00

We have two: #1 | #2

SR OvalTech 130mm BCD 52-tooth chainring #1. Used, $25.00

Lovely condition

And here's the flip side

SR OvalTech 130mm BCD 52-tooth chainring #2. Used, $25.00

Nice looking ring.

Side two