1980s MIELE MYB Dropbar Conversion

On Saturday, November 7, 2015 at 6:21:31 AM UTC-5, John B. wrote:
On Fri, 6 Nov 2015 23:22:35 -0800 (PST), Sir Ridesalot
wrote:

On Friday, November 6, 2015 at 7:32:09 PM UTC-5, John B. wrote:
On Fri, 6 Nov 2015 13:56:50 -0800 (PST), Sir Ridesalot
wrote:

Snipped
Biopace chainrings.

Cheers

Wow! You really go for the "old Stuff" :-)
--
cheers,

John B.

If it works and it's in good condition then I don't mind using it. Boipace is really nice on a loaded bike or for going up hills. It really smoothes things out and you can still spin with Biopace.

It's nice to be able to resurrect these old components and give them new life.

Cheers

I never rode a "biospace" but the ides seems very logical. How does it
feel on a level? Do you notice it at all?
--
cheers,

John B.

Feels fine to me, nice and smooth. Sheldon Brown liked them too

"
Among other bikes, I run Biopace on several of my fixed-gear machines, where high cadences are quite common in descending hills. In practice I have found no less ability to spin fast with Biopace chainrings, and, if anything, they permit me to spin faster without bouncing in the saddle.

Here's why: While your feet go around in circles, your legs basically go up and down in a reciprocating motion. With Biopace chainrings, your leg speed is faster in the middle of the stroke (when the cranks are horizontal) but slower at the top and bottom of the stroke (when the cranks are vertical.)

The slower motion at top and bottom means that your leg changes direction from upward to downward, or downward to upward motion at a slightly slower, more gentle speed. The increased leg speed near the middle of the stroke is the result of a more gradual acceleration/deceleration with the leg moving in the same direction. Bouncing in the saddle generally results from difficulty with changes in leg direction, not speed in the middle of the stroke. Thus, as Biopace makes it easier on your knees, it also can help you spin faster without bouncing!







Biopace and Fixed Gear

Cranksets of Sheldon's all-Biopace Piccio fixed-gear tandem.
Both sets of cranks have the same motion, controlled by the main drive chainwheel.
The matched Biopace chainwheels on the synchronizing chain have no effect.




People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain slack as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.
There is a slight variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.

[I've tried this too, but I'm not as happy with the change in tension. The sprocket is smaller than the chainring, so the chain doesn't meet the chainring at two points precisely opposite one another -- John Allen.]

Availability?


Snipped

Biopace chainrings and cranksets were made for 7-speed and 8-speed systems, but will work with 9-speed chain.

Snipped

A Biopace Story


I [John Allen] bought a Bike Friday travel bike at the factory in Eugene, Oregon in September, 2005. At Portland International Airport, the TSA's x-ray machine ejected the bicycle in its carrying case like a baseball from a pitching machine, to smash into into a rigid barrier at the bottom of a chute.

When I unpacked the bike at home, the chainwheel was bent. I replaced it with a Biopace chainwheel I had on hand.

In early 2006, I attended a winter training camp in Arizona run by legendary transcontinental record-setting cyclists Lon Haldeman and Susan Notorangelo. For a very short time on one of the rides, Lon was drafting behind me. Really! Mostly, he hung in there so he could exclaim about my bicycle. "You're riding Biopace!"

I replied apologetically, "it works OK for me, and it's what I had in my parts stash."

Lon replied, "Pete Penseyres and I did our transcontinental tandem ride in 1987 with all Biopace."

(Lon, ever modest, didn't mention that they set a record, 7 days, 14 hours, 55 minutes, which still stands as of 2014.)

A couple of years ago, I added a 28-tooth Biopace chainring, using the previously unoccupied 74-mm bolt circle of the Bike Friday's crankset. I haven't contrived a front derailer yet to work with the Bike Friday's unusual frame, so I have to shift the chain manually. That's OK because, thanks to the bicycle's small wheels, I only need to use the 28T chainring for very steep, long climbs. It has taken me to the summit of Mt. Wachusett, here in Massachusetts, at age 65, without walking, spinning all the way!


Conclusion


[Sheldon here.] Biopace chainwheels were made by Shimano and were also made under license by some other manufacturers. The shape of genuine Biopace chainwheels is not a simple ellipse, but a more complicated shape which Shimano described as a "point-symmetric egg curve." Other crankset makers have made similar designs, generally of simpler shape (pure elliptical) but oriented in a similar manner to Biopace chainwheels. Examples are SR's "Ovaltech" and Sugino's "Cycloid."

Non-round chainwheels remain controversial, especially among racers who think that everyone should ride racing bikes, but, in my opinion, they are of real value for the vast majority of non-racing cyclists.

Sheldon - the man


Copyright © 1995, 2008 Sheldon Brown


Harris Cyclery Home Page
If you would like to make a link or bookmark to this page, the URL is:
http://sheldonbrown.com/biopace.html

Last Updated: 11/07/2015 06:25:52 by John Allen"

Cheers

On Saturday, November 7, 2015 at 2:22:38 AM UTC-5, Sir Ridesalot wrote:
On Friday, November 6, 2015 at 7:32:09 PM UTC-5, John B. wrote:
On Fri, 6 Nov 2015 13:56:50 -0800 (PST), Sir Ridesalot
wrote:

Snipped
Biopace chainrings.

Cheers

Wow! You really go for the "old Stuff" :-)
--
cheers,

John B.

If it works and it's in good condition then I don't mind using it. Boipace is really nice on a loaded bike or for going up hills. It really smoothes things out and you can still spin with Biopace.

It's nice to be able to resurrect these old components and give them new life.

Cheers

I have a couple friends who loved Biopace, saying it was much easier on their
problematic knees. Me, I don't have enough experience with it to tell.

- Frank Krygowski

On Saturday, November 7, 2015 at 9:40:42 AM UTC-5, Frank Krygowski wrote:
On Saturday, November 7, 2015 at 2:22:38 AM UTC-5, Sir Ridesalot wrote:
On Friday, November 6, 2015 at 7:32:09 PM UTC-5, John B. wrote:
On Fri, 6 Nov 2015 13:56:50 -0800 (PST), Sir Ridesalot
wrote:

Snipped
Biopace chainrings.

Cheers

Wow! You really go for the "old Stuff" :-)
--
cheers,

John B.

If it works and it's in good condition then I don't mind using it. Boipace is really nice on a loaded bike or for going up hills. It really smoothes things out and you can still spin with Biopace.

It's nice to be able to resurrect these old components and give them new life.

Cheers

I have a couple friends who loved Biopace, saying it was much easier on their
problematic knees. Me, I don't have enough experience with it to tell.

- Frank Krygowski

Sheldon Brown also said that Biopace rings saved the knees. I often wonder how he used a Biopace ring on his fixed gear bike.

Scored another great condition Uniglide cog set for a couplev of $ the other day.

Cheers