I'm going to start accelerating in turns!
Ryan Cousineau
My Marinoni Pista (it is to the Pistadex what the TSX Composite is to
the DJIA) is nearly assembled: cranks go on this afternoon. The bar
ends consist of one champagne cork and one beer cork.
It is orange, and while I was going to call it stroopwaffel, recent
eerie events have convinced me to name it Speculaas.
Bike will be strictly indoors. This isn't really rbr-important, I'm
just so excited I'm telling everybody.
ilan
My Marinoni track bike is 29 years old (and I'm not trying to be
modest about age). It's a great bike that saw a fair amount of road
miles. I remember being amazed that steering was more neutral than my
mountain bike (kept its line better no hands) and convinced me that
this was a good criterion for judging frame design. What's weird now
is that it weighs more than my road bike.
-ilan
ABS
**Snip**
> The bar ends consist of one champagne cork and one beer cork.
Call me Rainman, but how can you stand that?
Don't you feel all....unbalanced?
ABS
thirty-six
> No really, because the banking is 47 degrees, 200m track.
>
> My Marinoni Pista (it is to the Pistadex what the TSX Composite is to
> the DJIA) is nearly assembled: cranks go on this afternoon. The bar
> ends consist of one champagne cork and one beer cork.
You did get the print upright?
Ryan Cousineau
> On Feb 2, 10:02 am, Ryan Cousineau <rcous...@gmail.com> wrote:
>
>
> > The bar ends consist of one champagne cork and one beer cork.
>
> Call me Rainman, but how can you stand that?
> Don't you feel all....unbalanced?
>
> ABS
After a few rounds, I'll be too dizzy to notice.
Ryan Cousineau
> On Feb 2, 6:02 pm, Ryan Cousineau <rcous...@gmail.com> wrote:
>
> > No really, because the banking is 47 degrees, 200m track.
>
> > My Marinoni Pista (it is to the Pistadex what the TSX Composite is to
> > the DJIA) is nearly assembled: cranks go on this afternoon. The bar
> > ends consist of one champagne cork and one beer cork.
>
> You did get the print upright?
Yes. I installed the bar tape while sober.
Not sober now, local beer shop had a gift-pack of 2 Westmalle beers
and one goblet,
RicodJour
>
> No really, because the banking is 47 degrees, 200m track.
>
> My Marinoni Pista (it is to the Pistadex what the TSX Composite is to
> the DJIA) is nearly assembled: cranks go on this afternoon. The bar
> ends consist of one champagne cork and one beer cork.
Have you thought about pressurizing your handlebars? When you win,
the champagne cork pops as you cross the line.
R
A. Dumas
> It is orange, and while I was going to call it stroopwaffel, recent
> eerie events have convinced me to name it Speculaas.
Ha ha. (edit: Stroopwafel.)
RicodJour
There is help if you need it...or at least a club.
http://meta.wikimedia.org/wiki/Association_of_Stroopwafel_Addicts
R
Ryan Cousineau
Well, I was going to name it Stroopwafel until the curious
Coincidental Speculaas Mentions.
Also, and this is even worse, I didn't line up the cork bar-end
lettering, so I have to go back and fix it.
Davey Crockett
| My Marinoni track bike is 29 years old (and I'm not trying to be
| modest about age). It's a great bike that saw a fair amount of road
| miles. I remember being amazed that steering was more neutral than my
| mountain bike (kept its line better no hands) and convinced me that
| this was a good criterion for judging frame design. What's weird now
| is that it weighs more than my road bike.
Time to trade in those cane rims
--
Davey Crockett
Ryan Cousineau
Surely the track is the one place where wood rims are just fine?
PS: actually got the Speculaas track bike onto the track tonight. I
survived, and after the routine initial terror, enjoyed it, so
complete success.
After I got home, I consumed perogies covered in bacon, washed down
with an Augustijn and chased by about six Ghirardelli peppermint
wafers. FAIL!
A. Dumas
> PS: actually got the Speculaas track bike onto the track tonight. I
> survived, and after the routine initial terror, enjoyed it, so
> complete success.
Nice.
> After I got home, I consumed perogies covered in bacon, washed down
> with an Augustijn and chased by about six Ghirardelli peppermint
> wafers. FAIL!
Nice.
thirty-six
> On Feb 6, 11:35 am, Davey Crockett <r...@azurservers.com> wrote:
>
> > ilan a écrit profondement:
>
> > | My Marinoni track bike is 29 years old (and I'm not trying to be
> > | modest about age). It's a great bike that saw a fair amount of road
> > | miles. I remember being amazed that steering was more neutral than my
> > | mountain bike (kept its line better no hands) and convinced me that
> > | this was a good criterion for judging frame design. What's weird now
> > | is that it weighs more than my road bike.
>
> > Time to trade in those cane rims
>
> > --
> > Davey Crockett
>
> Surely the track is the one place where wood rims are just fine?
>
> PS: actually got the Speculaas track bike onto the track tonight. I
> survived, and after the routine initial terror, enjoyed it, so
> complete success.
To synchronise fully with the track, you must wind your tape left-
handed. If you wind it balanced (symmetrical) it means you'll work
harder in the bends.
RicodJour
>
> Surely the track is the one place where wood rims are just fine?
>
> PS: actually got the Speculaas track bike onto the track tonight. I
> survived, and after the routine initial terror, enjoyed it, so
> complete success.
>
> After I got home, I consumed perogies covered in bacon, washed down
> with an Augustijn and chased by about six Ghirardelli peppermint
> wafers. FAIL!
How is that a fail? Unless you mean you should have had that tasty
meal prior to hitting the track. That would have been the right thing
to do. Master Fatties are supposed to reward themselves before they
do anything, and the extra ballast would have helped you come down off
the track as you're accelerating through the turns. Forget the wood
rims and work on your spare tire.
R
Fred Flintstein
The guy at the icebike event didn't wait until he had finished
the race before cracking open a beer.
http://cycleture.photoshelter.com/gallery-image/Penn-Ice-Cycle-Loppet/G0000L8z7ui5_vUE/I0000VfdcKN2YeL0
http://cycleture.photoshelter.com/gallery-image/Penn-Ice-Cycle-Loppet/G0000L8z7ui5_vUE/I0000VRDp8faVEv4
Not everyone believes in delayed gratification.
Fred Flintstein
Ryan Cousineau
> On Feb 8, 4:36 am, Ryan Cousineau <rcous...@gmail.com> wrote:
>
>
>
>
>
> > On Feb 6, 11:35 am, Davey Crockett <r...@azurservers.com> wrote:
>
> > > ilan a écrit profondement:
>
> > > | My Marinoni track bike is 29 years old (and I'm not trying to be
> > > | modest about age). It's a great bike that saw a fair amount of road
> > > | miles. I remember being amazed that steering was more neutral than my
> > > | mountain bike (kept its line better no hands) and convinced me that
> > > | this was a good criterion for judging frame design. What's weird now
> > > | is that it weighs more than my road bike.
>
> > > Time to trade in those cane rims
>
> > > --
> > > Davey Crockett
>
> > Surely the track is the one place where wood rims are just fine?
>
> > PS: actually got the Speculaas track bike onto the track tonight. I
> > survived, and after the routine initial terror, enjoyed it, so
> > complete success.
>
> To synchronise fully with the track, you must wind your tape left-
> handed. If you wind it balanced (symmetrical) it means you'll work
> harder in the bends.
An experienced, strong, but young rider at the track rode it in the
opposite direction as a lark, once. He said it was terrifying and felt
like he was about to crash for the whole time.
I rode it on a folding bike once,
Ryan Cousineau
It was failicious, but I didn't really want to so profoundly undo any
fitness gains that way.
RicodJour
Failicious - I like it. I think that would sell at least as well as
the Livedrunk stuff. There are more than a few Fashion Conscious
Fattie Femmes that happen to like the odd perogie wrapped in bacon.
I'd also figure in a fellatio angle just so's you have your bases
covered.
R
Fred Flintstein
> An experienced, strong, but young rider at the track rode it in the
> opposite direction as a lark, once. He said it was terrifying and felt
> like he was about to crash for the whole time.
I've never done it but a couple of guys at Blaine did. They
didn't say it was terrifying but they both felt like they
were going to slide off.
All the more reason to not wait for the race to finish
before cracking open a beer.
Fred Flintstein
Ryan Cousineau
Ryan Cousineau
Blaine is an impressively steep 43 degrees. Burnaby is 47.
Update: rode track Saturday night. Practiced dropping my chain. Didn't
crash.
Fred Fredburger
It's a great word. I'm stealing it and I'll worry about what it means later.
Fred
Dropped your chain? Rookie.
Fred
Ryan Cousineau
Dropped it TWICE. Didn't die, didn't kill anyone, did decide to call
it a night after #2.
Irony was that I had a completely successful first test, convinced
myself there was a chainline issue, and adjusted the crank to sit a
bit more inboard (I'm using a random road crank from my pile, and a
Biopace ring). After that improvement, I dropped my chain twice, both
to the outside, I think.
So dumbass=me.
Received wisdom at the track is no lockrings, but that wasn't an
issue: both times the chain dropped off both cogs, and so there was no
skidding, just a lot of coasting.
Anton Berlin
fixed gear with biopace rings?
Fred Flintstein
Exactly what I thought!
Fred Flintstein
Frederick the Great
<9f088708-89de-4923...@y12g2000prf.googlegroups.com>,
Ryan Cousineau <rcou...@gmail.com> wrote:
A non-circular chain ring is guaranteed to drop your chain.
--
Old Fritz
Fredmaster of Brainerd
Technically this should work (they're designed to
take up a constant amount of chain, IIRC) but in
practice it's going to be a class B fit.
Ryan, get a real chainring. Depending on the size
you need I might even have one I can mail you.
Ben
Scott
wrote:
No, they're not. Even a regular ring that's slightly out of round
will have at least one 'tight' spot that requires you to set the chain
tension based on that spot Depending on just how badly out of round
the ring is, it could easily be too loose at the loosest point.
Biopace on a fixie = fail.
thirty-six
Stop thinking, ditch the Biopace and the super flexxy uber-duper
derailleur chain. If you are not going with 1/8" system then get a
cheapo chinese/indian/pakistan 5/6-speed chain which tend to stick
rather than shift.
A. Dumas
> No, they're not. Even a regular ring that's slightly out of round
> will have at least one 'tight' spot that requires you to set the chain
> tension based on that spot Depending on just how badly out of round
> the ring is, it could easily be too loose at the loosest point.
> Biopace on a fixie = fail.
Have you even ridden a fixed gear, like, ever?
Scott
Yep. 6 seasons of racing (worked my way up to cat 2, which is no big
deal except I didn't start track racing until I was 37), and countless
thousands of winter base miles on a fixed gear over the last 20
years. Is there something in particular with what I wrote earlier
that you'd like to refute?
H. Fred Kveck
Scott <hendric...@hotmail.com> wrote:
That was a reference to the 2000 era when a John Hansen asked Shaun Wallace if
he'd ever ridden a fixed gear. See:
http://groups.google.com/group/rec.bicycles.racing/msg/bfcd823353ed41ce
By the way, you're absolutely right about chainrings and tension. It doesn't take
much ring off-centeredness (nice word, huh?) to make a chain get tight and loose. So
a Biopace ring is right out.
Fredmaster of Brainerd
wrote:
I think a Biopace chainring on a fixed gear is
a bad idea, but I also think we haven't come
up with a fully convincing explanation of why.
Biopace chainrings were designed so that
they have a constant amount of chain engaged,
just like a regular chainring. It sort of looks
like the chain take up should vary wildly, but
it doesn't. If it did, when you rode a Biopace
derailleur bike, the jockey pulley would be
constantly moving back and forth to take up
chain, and I've never seen that. The tension
ought to be about constant. In fact I think my
first singlespeed MTB hack had a Biopace ring
for a few days until I found a real ring.
As Scott said, no chainring is perfectly round.
But I don't see why a Biopace chainring would
be harder to center, since you do that by feel,
not by eyeball. Sure, it would have a tight and
loose spot, but no worse than a round ring.
The late great Sheldon Brown was inexplicably
a fan of Biopace, and he ran fixed gears with it:
http://www.sheldonbrown.com/biopace.html
Of course most of us aren't as good mechanics
as he was. My guess as to why Biopace on a fixie
is a bad idea is that the chain moves up and
down a little, and introducing that oscillation
plus a chain that's probably a little too loose
(not as good centering or chainline as Sheldon's,
etc) eventually throws chain.
Plus, Biopace looks like shit. Track bikes should
look either classic or like absurd Superbike futurism.
Oval chainrings are for gadget-minded trigeeks
and Bobby Julich.
Fredmaster Ben
thirty-six
I think it's that biopace is for those finding difficulty in getting
their legover. Advertising the problem wont help.
Scott
wrote:
I remember that thread and for a short moment thought that might be
where he was going with that, but wasn't sure. I guess I should've
just replied "once or twice".
Anton Berlin
I decided to find out what god thinks about biopace chainrings on a
fixed gear
http://www.sheldonbrown.com/biopace.html
Or maybe you need a ghost ring but good luck getting on the velodrome
with this set-up
Scott
No bottlecages!
Frederick the Great
Eccentricity is a sensitive subject so we make do
with neologisms and circumlocutions.
> to make a chain get tight and loose. So
> a Biopace ring is right out.
--
Old Fritz
Frederick the Great
<3e40717a-919e-498d...@q2g2000pre.googlegroups.com>,
A chain is wrapped around two cogwheels.
n_cog1 number of teeth on cogwheel 1.
n_cog2 number of teeth on cogwheel 2.
n_link number of links on the chain.
d distance between the centers of the cogwheels.
The pitch of the chain and cogwheels is 1/2 inch.
r_1 the radius of cogweel 1 in inches.
r_2 the radius of cogweel 2 in inches.
length the length of the chain in inches.
4 * PI r_1 = n_cog1.
length = 2 n_link.
t length of the outer tangent between points of tangency on the cogwheels.
t^2 + (r_1 - r_2)^2 = d^2.
phi angle the external tangent makes with the line of centers.
sin phi = (r_1 - r_2) / d.
So now
length / 2 = t + phi * ( r_1 - r_2) + PI / 2 * ( r_1 + r_2)
= (r_1 - r_2) arcsin((r_1 - r_2)/d)
+ d^2 - (r_1 - r_2)^2 + PI / 2 * ( r_1 + r_2)
Call the angle of rotation of the crank v. For an
eccentric chainring the radius of the ring at the point
of tangency varies with v, and the arclength of the
chainring between the two points of tangency varies
with v. The first effect changes the amount of wrap on
the rear cogwheel. Sure, a competent engineer can
design a chainring to balance these effects, but it
will only be good for the rear cogwheel, r_2, used in
the calculation. Again the variation may be small,
but how small? Small enough for the track?
--
Old Fritz
H. Fred Kveck
Fredmaster of Brainerd <bjwe...@gmail.com> wrote:
Ben, I'll readily admit I haven't even looked at a Biopace ring in years. I know
they aren't as exaggerated in shape as, say, an Osymetric ring. I do, however, think
that many of the ideas used to measure chain useage on a Osymetric ring would apply
to a Biopace ring (albeit to a lesser degree). The Osymetric ring isn't a true
ellipse. It has two sections that appear to have a similar radius as a round ring of
equal tooth count, only moved out from the centerline of the crank. There are two
sections that still appear to be of a similar or larger radius, only moved in from
the crank centerline. Then there are the transitional sections. To make it simple,
I'll call the sections that are moved out r+ and the sections that are moved in r-.
When the crank is positioned so the big radii are north/south, you have the chain
wrapped around two r+ sections and one r-. Since the cog is smaller than the ring,
the chain is wrapped around somewhat more than 180 degrees of the ring. When the
crank is rotated 90 degrees, the chain is wrapped around two r- sections and one r+.
Additionally, the difference in diameters between the cog and the ring is smaller;
hence the chain wrap is moved a bit closer to 180 degrees.
What I'm saying is this: even though an Osymetric ring has a theoretical
"circumference" that's equal to that of a round ring with the same number of teeth
(that theoretical "circumference" is actually the total length of the 1/2 inch
segments between the chain pins), the amount of chain the ring takes up in its
situation as a bike driveline is going to vary depending on how the ring is oriented
around the crank centerline. While Shimano says the Biopace ring is supposed to have
a constant amount of chain engaged, what I described above should still apply, though
to a lesser degree.
There's another thing that I think will make chain tension vary when a non-round
ring is used. A theoretical triangle can be made by the ring, cog and chain stay.
Draw a line between the tangent points the chain makes on the cog and the ring when
the ring is set so the big section is up and down. That'll be the hypotenuse. A line
parallel to the stay starting at the cog end of the hypotenuse is the adjacent side.
A line perpendicular to that up to the tangent point on the ring is the side
opposite. When the ring is rotated so the small arcs are up and down, the chain wrap
on the ring decreases a little, making the adjacent side a little longer (this will
be pretty minimal). But the side opposite does decrease, which will change the length
of the hypotenuse. This is taking place on both top and bottom sides of the stay. But
since the top side is under tension, all of the change in length is actually shifted
to the bottom, untensioned run. If a round ring that's a little off center will cause
the chain tension to vary, this should certainly do so too, only to a greater degree.
I could work this all out with real numbers but I have to admit that I'm not
interested enough to put the effort into working it up on the CAD. Sorry!
As for what you said about a bike with Biopace rings not causing the derailleur to
move (I think you mean the tension pulley, rather than the jockey), well, I haven't
looked at a bike using one so I don't know how much the derailleur might move. But
there is one thing I've noticed: the chain is pretty straight on the top while under
tension but it still has a bit of arc in its run on the bottom in spite of the
tension of the RD.
I think Ryan's chain drop problem is related partly to the tension issues the
Biopace ring add, and chainline error. Also: a fixed gear bike with good chainline
and proper tension doesn't "need" a 1/8 chain. Properly set up, it *does not care*
how wide the chain is.
Lastly: You're absolutely right about the aesthetic aspect. Biopace rings just
don't belong on a track bike. Besides, Shimano claims it's supposed to help the rider
pull through the "dead spots" in the pedal cycle. The fixed gear does that pretty
damn well by itself.
Anton Berlin
> In article
> <3e40717a-919e-498d-a935-c22db6b14...@q2g2000pre.googlegroups.com>,
And then Edison fills the lightbulb with water pours it into a beaker
and says "there's your measurement - exactly"
Scott
wrote:
>
> Lastly: You're absolutely right about the aesthetic aspect. Biopace rings just
> don't belong on a track bike. Besides, Shimano claims it's supposed to help the rider
> pull through the "dead spots" in the pedal cycle. The fixed gear does that pretty
> damn well by itself.
The only way a fixed gear is pulling the pedals through the dead spots
is for the chain tension to shift from the section running over the
top of the cog/ring to the section running under the bottom of the cog/
ring, where essentially the rotation of the wheel is pulling the
chain, in turn turning the cranks.
Unless you've got essentially no slack in the chain at all, you'd feel
the chain changing tension on every half-revolution of the cranks if
this were happening. The chunk/chunk/chunk sensation/noise would
drive you crazy.
You can't turn the cranks by pushing the chain on the top side. Don't
believe it, take the chain off, or just disconnect a link, and lay a
section of chain across the tops of the ring/cog of a fixie and then
rotate the wheel. The chain will just fall off the cog, but it won't
push the cranks 'round.
thirty-six
> On Feb 18, 1:33 am, "H. Fred Kveck" <YOURhow...@h-SHOESbomb.com>
> wrote:
>
>
>
> > Lastly: You're absolutely right about the aesthetic aspect. Biopace rings just
> > don't belong on a track bike. Besides, Shimano claims it's supposed to help the rider
> > pull through the "dead spots" in the pedal cycle. The fixed gear does that pretty
> > damn well by itself.
>
> The only way a fixed gear is pulling the pedals through the dead spots
> is for the chain tension to shift from the section running over the
> top of the cog/ring to the section running under the bottom of the cog/
> ring, where essentially the rotation of the wheel is pulling the
> chain, in turn turning the cranks.
>
> Unless you've got essentially no slack in the chain at all, you'd feel
> the chain changing tension on every half-revolution of the cranks if
> this were happening. The chunk/chunk/chunk sensation/noise would
> drive you crazy.
Correct training setup.
>
> You can't turn the cranks by pushing the chain on the top side. Don't
> believe it, take the chain off, or just disconnect a link, and lay a
> section of chain across the tops of the ring/cog of a fixie and then
> rotate the wheel. The chain will just fall off the cog, but it won't
> push the cranks 'round.
Wrong grease.
Choppy Warburton
Maybe that's why he used the word "pull" instead of "push".
Great insight otherwise.
Frederick the Great
<6462ff03-010f-4bd7...@k16g2000vbq.googlegroups.com>,
Anton Berlin <truth...@yahoo.com> wrote:
> And then Edison fills the lightbulb with water pours it into a beaker
> and says "there's your measurement - exactly"
The guys at Shimano did not design the chainring shape
by filling a lightbulb with water. Save your homilies
for the rubes, Will. Before venerating Edison, learn
about the less savory aspects of his character. Armstrong
is lily white in contrast.
--
Old Fritz
Scott
wrote:
Yeah, but a fixie still doesn't pull your cranks around, unless you
pedal like a drunken monkey.
Anton Berlin
H. Fred Kveck
Scott <hendric...@hotmail.com> wrote:
> On Feb 18, 1:33 am, "H. Fred Kveck" <YOURhow...@h-SHOESbomb.com>
> wrote:
> >
> > Lastly: You're absolutely right about the aesthetic aspect. Biopace
> > rings just
> > don't belong on a track bike. Besides, Shimano claims it's supposed to help
> > the rider
> > pull through the "dead spots" in the pedal cycle. The fixed gear does that
> > pretty
> > damn well by itself.
>
> The only way a fixed gear is pulling the pedals through the dead spots
> is for the chain tension to shift from the section running over the
> top of the cog/ring to the section running under the bottom of the cog/
> ring, where essentially the rotation of the wheel is pulling the
> chain, in turn turning the cranks.
You may well be right, Scott. I dunno, it always feels like the dead spots are
really minimal (meaning: less noticeable than on a freewheeling bike) when I ride my
fixed gear bike. Of course, it could be that my feet are being dragged around by the
wheel (heh).
> Unless you've got essentially no slack in the chain at all, you'd feel
> the chain changing tension on every half-revolution of the cranks if
> this were happening. The chunk/chunk/chunk sensation/noise would
> drive you crazy.
Well, I think the dead spots aren't really all that dead. There may be less (or
even a lot less) power being made in those sections of the pedal stroke but your feet
are still moving in a circle and don't let off so much that the chain would have time
to go into tension on the bottom run.
> You can't turn the cranks by pushing the chain on the top side. Don't
> believe it, take the chain off, or just disconnect a link, and lay a
> section of chain across the tops of the ring/cog of a fixie and then
> rotate the wheel. The chain will just fall off the cog, but it won't
> push the cranks 'round.
The reason I don't think that analogy works is because when the wheel makes the
crank turn, it does so by pulling on the bottom run, rather than pushing on the top.
Fredmaster of Brainerd
I don't believe in magic pulling you through dead spots
either on a fixie or Biopace. I did find that when climbing
standing on a fixed gear, there was a sensation of the
bike's momentum carrying your feet through the dead
spot - I don't think it eliminates the dead spot, just reduces
its strength. Of course, that's when climbing standing,
where my pedal stroke is uneven. Much less noticeable
on flat ground and spinning faster.
I once had a bike with round rings and a Biopace granny
(because I hadn't taken the crank off yet to change it).
After shifting from the round ring to the Biopace, the
pedal stroke felt completely weird, like something was
wrong with the bike, but the odd feeling disappeared after
a bit of pedaling (<30 seconds). Then when shifting back,
it felt weird again, until I adjusted back to the round ring.
The difference is a lot easier to tell with two diff. rings on the
same bike, because otherwise you adjust quickly. Which
kind of shows why there is no real difference and Biopace
has gone to bike-gimmick heaven.
Fredmaster Ben
Fredmaster of Brainerd
wrote:
>
> There's another thing that I think will make chain tension vary when a non-round
> ring is used. A theoretical triangle can be made by the ring, cog and chain stay.
> Draw a line between the tangent points the chain makes on the cog and the ring when
> the ring is set so the big section is up and down. That'll be the hypotenuse. A line
> parallel to the stay starting at the cog end of the hypotenuse is the adjacent side.
> A line perpendicular to that up to the tangent point on the ring is the side
> opposite. When the ring is rotated so the small arcs are up and down, the chain wrap
> on the ring decreases a little, making the adjacent side a little longer (this will
> be pretty minimal). But the side opposite does decrease, which will change the length
> of the hypotenuse. This is taking place on both top and bottom sides of the stay. But
> since the top side is under tension, all of the change in length is actually shifted
> to the bottom, untensioned run. If a round ring that's a little off center will cause
> the chain tension to vary, this should certainly do so too, only to a greater degree.
> I could work this all out with real numbers but I have to admit that I'm not
> interested enough to put the effort into working it up on the CAD. Sorry!
>
Damnit Howard,
You're writing an enormous screed just to provoke
me to dig out a Biopace ring and put it on my fixed
gear just to test this. I can see through your evil plan.
This is what Michael Press was deriving a formula
for, I think. His point appeared to be that the chainring
designer could make a shape that exactly canceled
the effect of changing hypotenuse of chain run for
one cog size, but it would not be exact for other cog
sizes.
I think if you tried to approximate the change in
hypotenuse you'll find it is of order ~0.7mm before
whatever tricks the biopace designers played. This
is not insignificant but not instantly fatal either.
Yes, I did mean the tension pulley, not the jockey.
> As for what you said about a bike with Biopace rings not causing the derailleur to
> move (I think you mean the tension pulley, rather than the jockey), well, I haven't
> looked at a bike using one so I don't know how much the derailleur might move. But
> there is one thing I've noticed: the chain is pretty straight on the top while under
> tension but it still has a bit of arc in its run on the bottom in spite of the
> tension of the RD.
>
> I think Ryan's chain drop problem is related partly to the tension issues the
> Biopace ring add, and chainline error. Also: a fixed gear bike with good chainline
> and proper tension doesn't "need" a 1/8 chain. Properly set up, it *does not care*
> how wide the chain is.
Fixed gear chain should match whatever the cog is.
> Lastly: You're absolutely right about the aesthetic aspect. Biopace rings just
> don't belong on a track bike. Besides, Shimano claims it's supposed to help the rider
> pull through the "dead spots" in the pedal cycle. The fixed gear does that pretty
> damn well by itself.
Maybe we could persuade the crowd that puts
pink or green aero rims on their fixies that they
need Biopace.
Fredmaster Ben
Simply Fred
> same bike, because otherwise you adjust quickly. Which
> kind of shows why there is no real difference and Biopace
> has gone to bike-gimmick heaven.
Someone should inform the Rotor people's advertising department to shut
them up.
Scott
>
> The reason I don't think that analogy works is because when the wheel makes the
> crank turn, it does so by pulling on the bottom run, rather than pushing on the top.
If you'd read/understood the entire post, you'd see the analogy works
perfectly. I pointed out, as you did, that the wheel is pulling the
cranks 'round via the bottom run, AND the critical thing to comprehend
is that if that were happening, you'd feel and hear the chain tension
changing from the top run to the bottom run.
My point was/is that while the only way for a fixed gear to turn the
cranks for you would be for the rotation of the wheel to be involved,
it does not happen unless you have a pathetically poor pedal stroke.
Over the years I've done a lot of over-geared climbing on a fixed
gear, deliberately running a slightly slacker chain than usual. At
the cadences I'd be turning, even the slightest relaxation of force on
the pedals would result in an obvious loss of chain tension, and the
chunk-chunk-chunk of the chain slackening/retightening with every half
revolution would drive me crazy if I didn't pull the pedals 'round
myself. I make no assertions that I was putting consistent power
through the entire pedal stroke, but I can assure you that once I'd
gotten good at climbing like that, at no time did the chain ever go
slack, much less become taut along the bottom run. The real trick was
learning to climb standing and never let the chain go slack.
Frederick the Great
<a2f812ad-f48f-43f5...@w6g2000vbo.googlegroups.com>,
Scott <hendric...@hotmail.com> wrote:
Uh, that would be me.
<http://www2.2space.net/images/upl_news/101229/1293595215.jpg>
--
Old Fritz
H. Fred Kveck
Fredmaster of Brainerd <bjwe...@gmail.com> wrote:
Sorry about that, Ben. It's just that, as I thought about it, it became more
obvious that there is a lot of subtle complexity to the geometry of the chain and
rings. And it's hard to describe without a lot of words.
> This is what Michael Press was deriving a formula
> for, I think. His point appeared to be that the chainring
> designer could make a shape that exactly canceled
> the effect of changing hypotenuse of chain run for
> one cog size, but it would not be exact for other cog
> sizes.
That could well be true. One of the things that makes it hard to calculate via
formulas, however, is the difference between the circumference of a smooth arc at
some diameter and the actual circumference created by an arc created out of 1/2"
chords (i.e. the chain links). The difference between those two increases as the
tooth count drops.
> I think if you tried to approximate the change in
> hypotenuse you'll find it is of order ~0.7mm before
> whatever tricks the biopace designers played. This
> is not insignificant but not instantly fatal either.
I wonder if you can design a lumpy ring so it can really eliminate all or even
much of the variation of how the chain is distributed around the ring during its
rotation. As I said, I haven't looked at a Biopace ring in years. You would have to
mount one up and empirically test it out if you (um, that's a generalized "you," not
you specifically) wanted to know. That'd be easier than taking the time to measure
where each chain roller is in relation to the crank centerline and feeding that info
into a CAD to play with.
> Yes, I did mean the tension pulley, not the jockey.
>
> > As for what you said about a bike with Biopace rings not
> > causing the derailleur to move (I think you mean the tension
> > pulley, rather than the jockey), well, I haven't looked at a bike
> > using one so I don't know how much the derailleur might
> > move. But there is one thing I've noticed: the chain is pretty
> > straight on the top while under tension but it still has a bit of
> > arc in its run on the bottom in spite of the tension of the RD.
> >
> > I think Ryan's chain drop problem is related partly to the
> > tension issues the Biopace ring add, and chainline error. Also:
> > a fixed gear bike with good chainline and proper tension doesn't
> > "need" a 1/8 chain. Properly set up, it *does not care* how wide
> > the chain is.
>
> Fixed gear chain should match whatever the cog is.
I should have said that rather than assume that it was understood. Sorry.
> > Lastly: You're absolutely right about the aesthetic aspect.
> > Biopace rings just don't belong on a track bike. Besides, Shimano claims
> > it's supposed to help the rider pull through the "dead spots" in the
> > pedal cycle. The fixed gear does that pretty damn well by itself.
>
> Maybe we could persuade the crowd that puts
> pink or green aero rims on their fixies that they
> need Biopace.
Evil!
H. Fred Kveck
<8d2b4643-47f4-47fd...@w36g2000vbi.googlegroups.com>,
Scott <hendric...@hotmail.com> wrote:
> On Feb 18, 9:36 pm, "H. Fred Kveck" <YOURhow...@h-
> >
> > The reason I don't think that analogy works is because when the wheel
> > makes the crank turn, it does so by pulling on the bottom run, rather
> > than pushing on the top.
>
> If you'd read/understood the entire post, you'd see the analogy works
> perfectly. I pointed out, as you did, that the wheel is pulling the
> cranks 'round via the bottom run, AND the critical thing to comprehend
> is that if that were happening, you'd feel and hear the chain tension
> changing from the top run to the bottom run.
Well, I did read and understand your post, Scott. I'll readily admit
that my wording in my post that you replied to was not optimal when I said
the following:
"Besides, Shimano claims it's supposed to help the rider pull through
the "dead spots" in the pedal cycle. The fixed gear does that pretty damn
well by itself."
I hoped I had clarified what I was saying when I wrote this:
"There may be less (or even a lot less) power being made in those
sections of the pedal stroke but your feet are still moving in a circle and
don't let off so much that the chain would have time to go into tension on
the bottom run."
Here's why I don't think the analogy works. The way you set it up, it's
a borderline static situation. I don't think it really can compare to the
dynamic situation that is what's happening when you're pedaling at a
reasonable rpm. It goes back to what I said above. Also: as one leg goes
through a "dead spot" the other leg is nearing the end of a power stroke.
Here's a visual comparison of left/right power output that should show you
what I'm trying to say.
<http://www.metrigear.com/wordpress/wp-content/uploads/2010/03/ClockPlot_For
ceProfile_TC_Seated1-1024x571.png>
(shortened: http://tinyurl.com/4ozdslc )
To show the entire pedal stroke for both legs, the two charts would be
overlaid, only one would be rotated 180 degrees.
> My point was/is that while the only way for a fixed gear to turn the
> cranks for you would be for the rotation of the wheel to be involved,
> it does not happen unless you have a pathetically poor pedal stroke.
All I'm saying, Scott, is that it's been my experience that I perceive my
feet to move around the circle somewhat better on my fixed gear bike at a
reasonable rpm than I do on a freewheeling bike.
> Over the years I've done a lot of over-geared climbing on a fixed
> gear, deliberately running a slightly slacker chain than usual. At
> the cadences I'd be turning, even the slightest relaxation of force on
> the pedals would result in an obvious loss of chain tension, and the
> chunk-chunk-chunk of the chain slackening/retightening with every half
> revolution would drive me crazy if I didn't pull the pedals 'round
> myself. I make no assertions that I was putting consistent power
> through the entire pedal stroke, but I can assure you that once I'd
> gotten good at climbing like that, at no time did the chain ever go
> slack, much less become taut along the bottom run. The real trick was
> learning to climb standing and never let the chain go slack.
I assume that means you were turning a fairly low rpm, then? I think the
standing at lower rpm situation that you're describing here amplifies the
dead spots. The Metrigear guys show that, to a degree. The two charts
toward the bottom are for 77 rpm and 91 rpm. I think you can extrapolate
that to a lower rpm (say, in the 60s or even 50s) and see that the
transition over the top gets worse.
http://www.metrigear.com/2010/03/19/is-your/
I think the method you described is probably a pretty good way to learn
to smooth out your pedal stroke. I've always climbed in bigger gears and
when I feel good, it feels like my stroke sweeps around the bottom a bit
more.
By the way, regarding the whole "pedaling circles" thing: the reality
may be a bit different than the theory, at least based on some of the tests
that Metrigear did.
<http://www.metrigear.com/2010/02/26/the-cyclist-as-a-two-cylinder-two-strok
e-engine/>
(shortened: http://tinyurl.com/ydc49nf )
Fred Fredburger
Tsk, tsk, quoting without attribution. Tesla should be given credit.
RicodJour
<FredFredF...@Where.Are.The.Nachos> wrote:
> On 2/18/2011 4:17 PM, Anton Berlin wrote:
> > On Feb 18, 4:51 pm, Frederick the Great<rub...@pacbell.net> wrote:
>
> >> about the less savory aspects of his character. Armstrong
> >> is lily white in contrast.
>
>
> Tsk, tsk, quoting without attribution. Tesla should be given credit.
Tesla was quite the courtly gentleman - he would never have used such
language.
I would think a quote from him would be more along the lines of...
"The similarity between Mr. Edison and a syphilitic pygmy's pudenda is
quite remarkable."
R
RBR go-to guy on everything Tesla (except the band - they sucked)
H. Fred Kveck
<82c50dcf-853c-4e5c...@x3g2000yqj.googlegroups.com>,
RicodJour <rico...@worldemail.com> wrote:
Isn't that about everything you need to know about the band?
Simply Fred
>> RBR go-to guy on everything Tesla (except the band - they sucked)
H. Fred Kveck wrote:
> Isn't that about everything you need to know about the band?
Its not about the music.
Ryan Cousineau
> But I don't see why a Biopace chainring would
> be harder to center, since you do that by feel,
> not by eyeball. Sure, it would have a tight and
> loose spot, but no worse than a round ring.
>
> The late great Sheldon Brown was inexplicably
> a fan of Biopace, and he ran fixed gears with it:
>
> http://www.sheldonbrown.com/biopace.html
>
> Of course most of us aren't as good mechanics
> as he was. My guess as to why Biopace on a fixie
> is a bad idea is that the chain moves up and
> down a little, and introducing that oscillation
> plus a chain that's probably a little too loose
> (not as good centering or chainline as Sheldon's,
> etc) eventually throws chain.
>
> Plus, Biopace looks like shit. Track bikes should
> look either classic or like absurd Superbike futurism.
> Oval chainrings are for gadget-minded trigeeks
> and Bobby Julich.
>
To clarify, chain drop wasn't a problem when my chainline was right.
Sheldon did indeed claim Biopace worked with fixies, and in a way, it
did for me too. However the chain tension does change a bit. I think
the "triangle" model explains why, maybe (but it's a bit complicated).
My chain was about as tight as you'd want it at the tightest, and
within reason at the loosest.
Solution: change ring to a round one and fix chainline. Tension is
nearly constant, chain doesn't fall off. Success.
Scott
>
> Solution: change ring to a round one and fix chainline. Tension is
> nearly constant, chain doesn't fall off. Success.
Booyah!
Fred Flintstein
Years ago (before singlespeed was trendy) I set up a
cyclocross bike as a singlespeed. Because I'm cheap I
used a cast-off biopace crank. After a while I threw
out all my cast-off biopace stuff.
Fred Flintstein
Simply Fred
> Solution: change ring to a round one and fix chainline. Tension is
> nearly constant, chain doesn't fall off. Success.
Didn't you forget the have a drink part before and/or after.
H. Fred Kveck
Fred Flintstein <bob.sc...@sbcremoveglobal.net> wrote:
How many minutes is "a while"?
Fred Flintstein
43 minutes into a 45 minute race I concluded it
wasn't a well thought out plan.
Fred Flintstein
Scott
wrote:
> On 2/21/2011 10:57 PM, H. Fred Kveck wrote:
>
>
>
> > Fred Flintstein<bob.schwa...@sbcremoveglobal.net> wrote:
>
> >> On 2/21/2011 12:59 PM, Scott wrote:
> >>> On Feb 21, 8:42 am, Ryan Cousineau<rcous...@gmail.com> wrote:
>
> >>>> Solution: change ring to a round one and fix chainline. Tension is
> >>>> nearly constant, chain doesn't fall off. Success.
>
> >>> Booyah!
>
> >> Years ago (before singlespeed was trendy) I set up a
> >> cyclocross bike as a singlespeed. Because I'm cheap I
> >> used a cast-off biopace crank. After a while I threw
> >> out all my cast-off biopace stuff.
>
> > How many minutes is "a while"?
>
> 43 minutes into a 45 minute race I concluded it
> wasn't a well thought out plan.
>
> Fred Flintstein
You probably weren't thinking clearly at that point.
William Fred
news:Y_SdnRfxU4skUf7Q...@giganews.com:
>
> 43 minutes into a 45 minute race I concluded it
> wasn't a well thought out plan.
>
How long was the race for everyone else?
--
Bill Fred
A. Dumas
> Fred Flintstein wrote:
>> 43 minutes into a 45 minute race I concluded it
>> wasn't a well thought out plan.
>
> How long was the race for everyone else?
Nice.
thirty-six
> Fred Flintstein <bob.schwa...@sbcremoveglobal.net> wrote innews:Y_SdnRfxU4skUf7Q...@giganews.com:
>
>
>
> > 43 minutes into a 45 minute race I concluded it
> > wasn't a well thought out plan.
>
> How long was the race for everyone else?
>
> --
> Bill Fred
Cyclocross.