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(503) 480-2001
email: sscycleworks@comcast.net
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Shimano Biopace chainrings in 74, 110 & 130mm Bolt Circle Diameter (BCD)

On this page: 74mm BCD Biopace rings | 110 BCD Biopace rings | 130 BCD Biopace rings
SR & Sugino elliptical chainrings are posted here.

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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 Biopace Chainrings: 28 tooth

28-tooth, 74mm BCD Shimano Biopace chainring.

We have several: New | Used | Steel used #1 (black) | #2 (black) | #3 | #4

28-tooth, 74mm BCD Shimano Biopace chainring. New, $35.00

We have three in stock

Biopace 28-tooth chainring

28-tooth, 74mm BCD Shimano Biopace chainring. used, $25.00

Biopace chainring

Many hills left in this ring.

Shimano Biopace chainring

And the ring turned over.

28-tooth, 74mm BCD steel Shimano Biopace chainring #1. Used, $25.00

Biopace steel chainring

Lightly used

28-tooth steel Biopace chainring

The flip side.

28-tooth, 74mm BCD steel Shimano Biopace chainring #2. Used, $25.00

Steel 28-tooth biopace chainring

Light use

Shimano Biopace chainring

And the same ring flipped over

28-tooth, 74mm BCD steel silver Shimano Biopace chainring #3. Used, $25.00

Shimano Biopace chainring

Front side

Shimano Biopace chainring

The back side

28-tooth, 74mm BCD steel silver Shimano Biopace chainring #4. Used, $15.00

Biopace 28-tooth chainring

Side 1

Biopace chainring

Side 2


110 BCD Biopace chainrings: 38 tooth | 48 tooth | 50 tooth

38-tooth, 110 BCD Biopace chainrings.

We have two: Aluminum | Steel

38-tooth, 110 BCD aluminum Biopace chainring. Used, $35.00

Biopace chainring

Top view

Biopace chainring

And the same 38-tooth ring flipped over.

38-tooth, 110 BCD steel Biopace chainring. Used, $15.00

Steel Biopace chainring

This ring will last a very long time

Biopace steel chainring

And here's the back side.


48-tooth, 110 BCD Biopace chainrings.

We have several: New | Used #1 | Used #2 | Used steel

48-tooth, 110 BCD black-anodized Biopace chainring. New, $80.00

Biopace 110 BCD chainring

Here it is out of its packaging.

Biopace chainring

It is new and in its orginal factory packaging.

48-tooth, 110 BCD used Biopace chainring #1, $50.00

Biopace 110 BCD chainring

Top side

Biopace chainring

And the back side.

48-tooth, 110 BCD used Biopace chainring #2, $50.00

Biopace 110 BCD 48-tooth chainring

Lovely condition

Biopace chainring

And the back side of the same ring.

48-tooth, 110 BCD steel Biopace chainring. Used, $15.00

Biopace steel chainring

Inexpensive and will last for nearly all time. Nearly, but not quite.


50-tooth, 110 BCD Biopace chainring. Lightly used, $50.00

Biopace 50-tooth chainring

It's had just a little use.

Biopace chainring

And it looks just as good flipped over.


130 BCD Biopace chainrings: 42-tooth | 52-tooth

42-tooth, 130 BCD Biopace chainrings.

We have several:
New (all were taken off new bikes) #1 | #2 | #3 | #4
Used: #1 | #2 | #3 | #4 | #5 | #6 | #7

42-tooth, 130 BCD Biopace chainring #1. New, $50.00

Taken off a new bike.

Biopace chairing

Side one.

Biopace chainring

And the flip side

42-tooth, 130 BCD Biopace chainring #2. New, $40.00

Taken off a new bike.

Biopace chairing

Hasn't seen the road yet.

Biopace 42-ooth chairing

Side 2

42-tooth, 130 BCD Biopace chainring #3. New, $40.00

Taken off a new bike.

Biopace chainring

Side 1

Shimano Biopace chainring

Side 2

42-tooth, 130 BCD Biopace chainring #4. New, $40.00

Taken off a new bike.

Biopace chainring

Side 1

Biopace 42-tooth chainring

Side 2

42-tooth, 130 BCD used Biopace chainring #1. New, $25.00

Biopace chainring

Front side

Biopace chainring

And the back side

42-tooth, 130 BCD used Biopace chainring #2. New, $25.00

Shimano Biopace chainring

Front side

Shimano Biopace chainring

And the back side

42-tooth, 130 BCD used Biopace chainring #3. New, $25.00

Biopace chainring

Side 1

Biopace chainring

And the ring flipped over

42-tooth, 130 BCD used Biopace chainring #4. New, $25.00

Biopace chainring

Side 1

Biopace chainring side 2

Side 2

42-tooth, 130 BCD used Biopace chainring #5. New, $25.00

Biopace 42-tooth chainring

Been on a bike, but it has lots of miles left.

Biopace 42-tooth chainring

And here it is flipped over

42-tooth, 130 BCD used Biopace chainring #6. New, $25.00

Biopace chainring

The business side with the specs

Biopace chainring

And the same 42-tooth ring flipped over

42-tooth, 130 BCD used Biopace chainring #7. New, $25.00

Biopace 42-tooth chainring

Side 1

Biopace chainring

And side 2


52-tooth, 130 BCD Biopace chainrings.

We have several:
New: #1 | #2 | #3 | #4 | #5 | #6
Used: #1 | #2 | #3 | #4 | #5

52-tooth 130 BCD Shimano Biopace chainring #1. New, $80.00

Biopace 52-tooth chainring

New, in its factory package.

Shimano new 52-tooth biopace chainring

And out of its package for a close-up

52-tooth 130 BCD Shimano Biopace chainring #2. New, $80.00

Shimano Biopace chainring

Factory fresh

Shimano Biopace chainring.

Mr. DeMille, I'm ready for my close-up.

52-tooth 130 BCD Shimano Biopace chainring #3. New, $80.00

Biopace chainring

Available in silver, as well.

52-tooth 130 BCD Shimano Biopace chainring #4. New, $80.00

52-tooth Shimano Biopace chainring

This taken off a new bike.

52-tooth 130 BCD Shimano Biopace chainring #5. New, $80.00

Shimano Biopace chainring

This was taken off a new bike.

52-tooth 130 BCD Shimano Biopace chainring #6. New, $80.00

Biopace chainring

New, but taken off a new bike.

Biopace chainring

And the flip side

52-tooth 130 BCD Shimano Biopace chainring #1. Used, $25.00

Biopace 52-tooth chainring

Top side

Biopace chainring

And the back side

52-tooth 130 BCD Shimano Biopace chainring #2. Used, $25.00

Biopace chainring

Used, but only a bit

Biopace 52-tooth chainring

And just as nice on the back side

52-tooth 130 BCD Shimano Biopace chainring #3. Used, $25.00

Shimano Biopace chainring

The business side

Biopace chainring

And the back side

52-tooth 130 BCD Shimano Biopace chainring #4. Used, $25.00

Biopace chainring

Lightly used

Shimano Biopace chainring

And the same ring flipped over

52-tooth 130 BCD Shimano Biopace chainring #5. Used, $25.00

Shimano Biopace chainring

Front side

Biopace 52-tooth chainring

And the back side