Bio Pace?

Mon, 09 Aug 2004 16:56:49 -0700, <[email hidden]>,

Bill Baka said:

I am also curious about the exact positioning of
the chainring since it can be one of five.

BioPace chainwheels are fitted so the small radius is engaged when the
cranks are horizontal - large radius engaged when they are vertical.

http://www.sheldonbrown.com/biopace.html
--
zk

"Zoot Katz" wrote: BioPace chainwheels are fitted so the small radius is
engaged when the cranks are horizontal - large radius engaged when they are
vertical.
^^^^^^^^^^^^^^^
Correct on Zoot's part, and really dumb on Shimano's part. A number of
years ago I bought a set of elliptical chainrings for my mountain bike.
These were designed and manufactured by a mechanic who was an ex-Shimano
employee. He told me that the Biopace design was based on logic that had a
few bad leaps in it. They did studies of people walking, and tried to
simulate the motion of the feet walking, with the cranks. This resulted in
the odd-ball condition which "Zoot" correctly describes. My mechanic friend
specified that the long axis of the ellipses be positioned at 90 degrees to
the pedal axis, so you go through top-dead-center quickly. The reason is
that that is the position where you have the least leverage. His idea was
to give you lower gearing in that part of the stroke where you are actually
doing the pushing. It worked for me.

Because of the five position bolt pattern, you can't rotate the rings by 90
degrees, but I recommend you do the best you can. One person commented,
"The more Shimano 'improves' them, the rounder they get."

Bill Baka said:

Has anybody ever ridden with a bio pace chainring?
I just became the owner of a Schwinn Super sport with
one on it and haven't been able to ride it yet due
to a lack of air in the tires (trick valves).
What should I expect? The bike appears to be for
flats only as the gears are all high and higher,
no climbing gears at all.
If I didn't know better I would think it is a
time trial bike.
I am also curious about the exact positioning of
the chainring since it can be one of five.
Aren't these supposed to be so that the crank turns
through the dead zonea at the top/bottom of each
stroke faster?
Bill Baka

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As you'll read in the Sheldonbrown link, Biopace chainrings aren't eliptical, in fact they are the opposite. The small radius of the ring engages when the cranks are horizontal, and the larger radius engages when the cranks are vertical.

I have a bike that had been setup for time trial, and it has a biopace chainring. I have no issues with it. I changed my cassette to give me some "climbing gears" and it's fine. Although, I have little experience as a rider to give an educated assessment.

Leo Lichtman said:

"Zoot Katz" wrote: BioPace chainwheels are fitted so the small radius is
engaged when the cranks are horizontal - large radius engaged when they
are
vertical.
^^^^^^^^^^^^^^^
Correct on Zoot's part, and really dumb on Shimano's part. A number of
years ago I bought a set of elliptical chainrings for my mountain bike.
These were designed and manufactured by a mechanic who was an ex-Shimano
employee. He told me that the Biopace design was based on logic that
had a
few bad leaps in it. They did studies of people walking, and tried to
simulate the motion of the feet walking, with the cranks. This resulted
in
the odd-ball condition which "Zoot" correctly describes. My mechanic
friend
specified that the long axis of the ellipses be positioned at 90 degrees
to
the pedal axis, so you go through top-dead-center quickly. The reason is
that that is the position where you have the least leverage. His idea
was
to give you lower gearing in that part of the stroke where you are
actually
doing the pushing. It worked for me.

Because of the five position bolt pattern, you can't rotate the rings by
90
degrees, but I recommend you do the best you can. One person commented,
"The more Shimano 'improves' them, the rounder they get."

OK, these sound kind of weird to ride. With 5 mounting holes it would seem
that I could try 5 different angles relative to the crank and see if any
of them feels right. It sounds like I will be getting a round ring on
there soon.
Thanks,
Bill Baka

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Bill Baka said:

Has anybody ever ridden with a bio pace chainring?
I just became the owner of a Schwinn Super sport with
one on it and haven't been able to ride it yet due
to a lack of air in the tires (trick valves).

Those are Presta valves. Get a suitable pump, or buy
presta-to-Schraeder adaptors at the bikeshop.

=Luigi

Quoted message said:

What should I expect? The bike appears to be for
flats only as the gears are all high and higher,
no climbing gears at all.
If I didn't know better I would think it is a
time trial bike.
I am also curious about the exact positioning of
the chainring since it can be one of five.
Aren't these supposed to be so that the crank turns
through the dead zonea at the top/bottom of each
stroke faster?
Bill Baka

....and now for something ELSE completely different...

I have had opportunity to ride both Shimano Bio-pace and Sugino Oval-Tech.

and...

I can't honestly tell the difference between the 'not round' chainrings and
round ones...

Of course, the BP set I have is strictly low end, the chainrings are riveted
to the crankarm spider, and the OT; while bolted together, has an odd bolt
pattern - you can really only mount 'em one way...

Richard Ballantyne, of "Richard's 20th Century Bike Book", calls the 'not
round' chainring fad "the lie that may have been true".

Quoted message said:

Has anybody ever ridden with a bio pace chainring?

Yes.

My fifteen-year-old hybrid has a Shimano biopace chainset.

I feel absolutely no difference between it and "normal" chainrings, so for me,
biopace is a gimmick.

Cheers, helen s

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I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Bill Baka said:

Has anybody ever ridden with a bio pace chainring?
I just became the owner of a Schwinn Super sport with
one on it and haven't been able to ride it yet due
to a lack of air in the tires (trick valves).
What should I expect? The bike appears to be for
flats only as the gears are all high and higher,
no climbing gears at all.
If I didn't know better I would think it is a
time trial bike.
I am also curious about the exact positioning of
the chainring since it can be one of five.
Aren't these supposed to be so that the crank turns
through the dead zonea at the top/bottom of each
stroke faster?
Bill Baka

DaveH said:

I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Personally, I don't think new bikes have superior braking, either. I can
stop just as well on my 15 year old Trek as I can on my one year old
Lemond. Now, shifting on racing bikes - that's a different story. I will
have to say that I thought biopace sucked except for the small chainring
on my mountain bike, then I liked it.

--
Bob in CT
Remove ".x" to reply

"Bob in CT" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

DaveH said:

I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Personally, I don't think new bikes have superior braking, either. I can
stop just as well on my 15 year old Trek as I can on my one year old
Lemond. Now, shifting on racing bikes - that's a different story. I will
have to say that I thought biopace sucked except for the small chainring
on my mountain bike, then I liked it.

--
Bob in CT
Remove ".x" to reply

You might want to compare your new bike's and your old bike's braking
downhill in the rain. When I replaced my old Shimano 600 brakes with double
pivot 600 brakes on a Trek 1500 a lot of years ago there was a dramatic
difference in power and modulation.

I agree with you on bio-space. It sucked. First thing I did with a new bike
some years ago was pitch the rings. If you don't ride you wouldn't know the
difference. If you have been riding round rings for a while it feels really
strange, like stepping into a hole.
Bill

Bill said:

"Bob in CT" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

DaveH said:

I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Personally, I don't think new bikes have superior braking, either. I
can
stop just as well on my 15 year old Trek as I can on my one year old
Lemond. Now, shifting on racing bikes - that's a different story. I
will
have to say that I thought biopace sucked except for the small chainring
on my mountain bike, then I liked it.

--
Bob in CT
Remove ".x" to reply

You might want to compare your new bike's and your old bike's braking
downhill in the rain. When I replaced my old Shimano 600 brakes with
double
pivot 600 brakes on a Trek 1500 a lot of years ago there was a dramatic
difference in power and modulation.

[cut]

That I haven't done, and mainly because the new bike (Lemond) is much
nicer in fit than my old bike (Trek), so I've relegated the Trek to inside
duties. I did ride the Trek a few times after buying the Lemond, and I
couldn't tell any difference in many things, including braking and ride
quality (glued aluminum tubes v. welded steel). However, I've not
compared the two during the rain.

--
Bob in CT
Remove ".x" to reply

I had a triple chain ring bike with biopace and I did not like it. The out of
round aspect of the biopace increased with the smaller the chain ring to the
point that the small ring looked a bit like a smushed quadrilateral.
Unfortunately, the small ring felt like I was pedalling a smushed quadrilateral
also. It was nasty. The big ring was not that much out of round so it was
less objectionable. I much prefer round chain rings to biopace. Biopace was
the high tech "improvement" that wasn't.

Pbwalther said:

I had a triple chain ring bike with biopace and I did not like it. The
out of
round aspect of the biopace increased with the smaller the chain ring to
the
point that the small ring looked a bit like a smushed quadrilateral.
Unfortunately, the small ring felt like I was pedalling a smushed
quadrilateral
also. It was nasty. The big ring was not that much out of round so it
was
less objectionable. I much prefer round chain rings to biopace.
Biopace was
the high tech "improvement" that wasn't.

And the really bad thing was that [censored] basically forced you to buy
Biopace on any new bike purchased during that period. Both my mountain
bike (now gone) and racing bike (still around) had Biopace.

--
Bob in CT
Remove ".x" to reply

Pbwalther said:

I had a triple chain ring bike with biopace and I did not like it. The
out of
round aspect of the biopace increased with the smaller the chain ring to
the
point that the small ring looked a bit like a smushed quadrilateral.
Unfortunately, the small ring felt like I was pedalling a smushed
quadrilateral
also. It was nasty. The big ring was not that much out of round so it
was
less objectionable. I much prefer round chain rings to biopace.
Biopace was
the high tech "improvement" that wasn't.

And the really bad thing was that [censored] basically forced you to buy
Biopace on any new bike purchased during that period. Both my mountain
bike (now gone) and racing bike (still around) had Biopace.

--
Bob in CT
Remove ".x" to reply

On Tue, 10 Aug 2004 15:49:29 GMT, Bob in CT <[email hidden]>

Quoted message said:

DaveH said:

I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Personally, I don't think new bikes have superior braking, either. I can
stop just as well on my 15 year old Trek as I can on my one year old
Lemond. Now, shifting on racing bikes - that's a different story. I will
have to say that I thought biopace sucked except for the small chainring
on my mountain bike, then I liked it.

Right--The Shimano 600 brakes probably need new pads. Also, the stock
rims are warped at each spoke insertion point. The net effect is
mediocre, pulsating braking.

The Shimano 600sis rear derailleur plus Indexed down-tube shifter
simply works very well, though I guess it's not quite as crisp and
precise as new 105 or Ultegra with STI or "brifters", which I detest.

Bill said:

"Bob in CT" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

DaveH said:

I have an 87 Super Sport with biopace chain rings. As far as I can
tell, the ring is positioned such that a radial drawn through the
largest diameter is collinear with the cranks.

I observe a slight difference in feel between round chainrings and
biopace rings. Not significant.

I really like the Super Sport, by the way. With the exception of
superior braking, I'm not sure the new bikes are truly that much
superior. But I'm a duffer.
Dave

Personally, I don't think new bikes have superior braking, either. I can
stop just as well on my 15 year old Trek as I can on my one year old
Lemond. Now, shifting on racing bikes - that's a different story. I will
have to say that I thought biopace sucked except for the small chainring
on my mountain bike, then I liked it.

--
Bob in CT
Remove ".x" to reply

You might want to compare your new bike's and your old bike's braking
downhill in the rain. When I replaced my old Shimano 600 brakes with double
pivot 600 brakes on a Trek 1500 a lot of years ago there was a dramatic
difference in power and modulation.

I agree with you on bio-space. It sucked. First thing I did with a new bike
some years ago was pitch the rings. If you don't ride you wouldn't know the
difference. If you have been riding round rings for a while it feels really
strange, like stepping into a hole.
Bill

I'm about 2 months back into cycling after about 15 years. Still, I'm
familiar with biopace so round feels slightly odd. I assume round is
more correct since you and the other experienced posters conclude
this.

I've got a Rambouillet UPS bound (thursday?) with round rings. I
assume I'll ultimately find this to be superior.

-----BEGIN PGP SIGNED MESSAGE-----

In article <[email hidden]>,

DaveH said:

Bill said:

I agree with you on bio-space. It sucked. First thing I did with a new bike
some years ago was pitch the rings. If you don't ride you wouldn't know the
difference. If you have been riding round rings for a while it feels really
strange, like stepping into a hole.
Bill

I'm about 2 months back into cycling after about 15 years. Still, I'm
familiar with biopace so round feels slightly odd. I assume round is
more correct since you and the other experienced posters conclude
this.

_ I wouldn't say "more correct". Just different.

Quoted message said:

I've got a Rambouillet UPS bound (thursday?) with round rings. I
assume I'll ultimately find this to be superior.

_ I think it has more to do with what you're used to. I rode
a Biopace mountain bike for years and the only thing that I
really disliked about it was the horrible chain suck. If you
like BioPace you can still get the rings on Ebay if you want.

_ You and Sheldon can start the BioPace fan club....

_ Booker C. Bense

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"Booker C. Bense" wrote: . If you like BioPace you can still get the rings
on Ebay if you want.
^^^^^^^^^^^^
There is a place in Berkeley, CA, called Recycle Bike Shop--their back room
is a gold mine of old and not-so-old parts. Of course, it goes without
saying that they have PLENTY of Biopace chain rings. Phone (510) 655-1889.
IMHO, even ONE Biopace chain ring is way more than enough.

Thu, 12 Aug 2004 20:24:43 GMT,
<[email hidden]>,

Leo Lichtman said:

IMHO, even ONE Biopace chain ring is way more than enough.

Not entirely true.

Because of their weird shape you can't hack five decent spacers (for
converting a road double crank to single-speed use) out of one ring.
You must destroy two of them.

That's not as bad as it sounds because the aluminium is still
recyclable.
--
zk