crankset design

Francesco Devittori said:

I see racers that strip the paint off their frames to save
weight, I see others that drills holes everywhere (Mayo at
Ventoux TT for ex.) and looking at the crankset I wonder
if nobody tried something different than the traditional
design. What about two arms, each with a small wheel (like
the rear der. pulley)? One arm could change its angle to
get a lower/higher gear. No front der (some mechanism to
change that angle would be needed), no chainrings. Plus
the chain won't have to change ring => no risk of falling
down. frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody tried
some alternative solution!

Francesco

oooops I realized that with this solution it would be
somewhat difficult to make the chain move while pushing the
pedals :-)

However I'm still curious about alternative desings...

Francesco Devittori said:

...looking at the crankset I wonder if nobody tried
something different than the traditional design. What
about two arms, each with a small wheel (like the rear
der. pulley)? One arm could change its angle to get a
lower/higher gear. No front der (some mechanism to change
that angle would be needed), no chainrings. Plus the chain
won't have to change ring => no risk of falling down.
frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody tried
some alternative solution!

If I understand it correctly, the small pulleys travel in a
circle around the bottom bracket spindle. That would sorta
work if the pulleys were not allowed to rotate
independently. But the mechanical advantage of the system
would vary depending on the angle of the pedal arm, and the
derailler would need to take up the extra slack at 4X the
pedal rpm. In other words, it wouldn't work very well.

But now let's put more pulleys out there. Pretty soon you
approximate a circle and the problems I just described would
no longer exist. But now you can't change the gear ratio
because the pulleys would interfere if you tried to make the
radius smaller. So a regular chainring would work just as
well or better and it would be lighter.

--
Dave dvt at psu dot edu

Francesco Devittori <frenkatfrenkdtcm> wrote in message news:<[email hidden]>...

Quoted message said:

Francesco Devittori said:

I see racers that strip the paint off their frames to
save weight, I see others that drills holes everywhere
(Mayo at Ventoux TT for ex.) and looking at the crankset
I wonder if nobody tried something different than the
traditional design. What about two arms, each with a
small wheel (like the rear der. pulley)? One arm could
change its angle to get a lower/higher gear. No front
der (some mechanism to change that angle would be
needed), no chainrings. Plus the chain won't have to
change ring => no risk of falling down.
frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody
tried some alternative solution!

Quoted message said:

oooops I realized that with this solution it would be
somewhat difficult to make the chain move while pushing
the pedals :-)

However I'm still curious about alternative desings...

Why are you now questioning what's been in existence, and
proven, for easily over 100 years? Well, if you really
want *different* cranks, perhaps you can look for a set of
these to use:

PMP crankset:
classicrendezvous.comPMP main.htmOpen ↗

or how about a 10-arm Colnago design (scroll down to 3rd
photo): classicrendezvous.comCOpen ↗
ampag_rare.htm

Maybe you can make this work:
classicrendezvous.comcheckered flag.htmOpen ↗

bfd said:

Quoted message said:

Francesco Devittori wrote:

However I'm still curious about alternative desings...

Why are you now questioning what's been in existence, and
proven, for easily over 100 years? Well, if you really
want *different* cranks, perhaps you can look for a set of
these to use:

PMP crankset:
classicrendezvous.comPMP main.htmOpen ↗

or how about a 10-arm Colnago design (scroll down to 3rd
photo): classicrendezvous.comCampagnoloOpen ↗
/Campag_rare.htm

Maybe you can make this work:
classicrendezvous.comcheckered flag.htmOpen ↗

Unless someone will mathematically prove that the current
design is the most efficient, the lightest and the most
troublefree you can assume that a better solution *could*
exist. Of course it won't be easy to find something better,
but if everybody in the past had the "there's nothing better
than what exists"-philosophy we would probably not ride
bicycles, and surely not write on a newsgroup.

Quoted message said:

Why are you now questioning what's been in existence, and
proven, for easily over 100 years?

Nice job with the constructive criticism...

--
Phil, Squid-in-Training

In article <[email hidden]>,
frenkatfrenkdtcm says...

Quoted message said:

I see racers that strip the paint off their frames to save
weight, I see others that drills holes everywhere (Mayo at
Ventoux TT for ex.) and looking at the crankset I wonder if
nobody tried something different than the traditional
design. What about two arms, each with a small wheel (like
the rear der. pulley)? One arm could change its angle to
get a lower/higher gear. No front der (some mechanism to
change that angle would be needed), no chainrings. Plus the
chain won't have to change ring => no risk of falling down.
frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody tried
some alternative solution!

Many years ago I remember seeing a similar device for sale.
It was slightly different. It used more than two jockey
wheels. Something like 6. They all were on radial sliding
tracks. When you shifted gears the wheels would move in and
out. I have no idea who well it worked.
----------------
Alex

In article
<[email hidden]>,
[email hidden] says...

Quoted message said:

Why are you now questioning what's been in existence, and
proven, for easily over 100 years? Well, if you really
want *different* cranks, perhaps you can look for a set of
these to use:

PMP crankset:
classicrendezvous.comPMP main.htmOpen ↗

Wasted metal. It is the same as a straight arm crank.

Quoted message said:

or how about a 10-arm Colnago design (scroll down to 3rd
photo): classicrendezvous.comclassicrendezvous.comOpen ↗
Campag_rare.htm

Looks like a photoshop special, not a real crank.

Quoted message said:

Maybe you can make this work:
classicrendezvous.comcheckered flag.htmOpen ↗

I can't quite figure out how this works, but I would
question how much energy it could store and then release.
--------------
Alex

"Alex Rodriguez" wrote: (clip) When you shifted gears the
wheels would move in and out. I have no idea who well it
worked. ^^^^^^^^^^^^^ Nice idea IN THEORY. I'll bet it
proved terribly unreliable, and was probably heavier than
regular chainrings.

"Alex Rodriguez" wrote: Wasted metal. It is the same as a
straight arm crank. ^^^^^^^^^^^ Absolutely right, Alex. It's
the same, only worse, "cause it's heavier and more flexible.
For those who don't get it, I will add that the shape of a
lever has no effect on its mechanical advantage--its line of
action is the line connecting the end points.

"Francesco Devittori" <frenkatfrenkdtcm> wrote in message
"]news:[email hidden]...

Quoted message said:

I see racers that strip the paint off their frames to save
weight, I see others that drills holes everywhere (Mayo at
Ventoux TT for ex.) and looking at the crankset I wonder
if nobody tried something different than the traditional
design. What about two arms, each with a small wheel (like
the rear der. pulley)? One arm could change its angle to
get a lower/higher gear. No front der (some mechanism to
change that angle would be needed), no chainrings. Plus
the chain won't have to change ring => no risk of falling
down. frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody tried
some alternative solution!

Francesco

its been done but I cant find any links about them. 1936.
nealeson expandable chainwheel. chainwheel sections could be
moved while riding into five separate separate diameters,
with a range of 2 to 1, say 26-52 teeth.

I have no idea what this looked like or how it worked

1973 don hagen at TCM, used 6 small cogs traveling in a
spiral groove(looks the same as a latch chuck). 2.5 turns of
the pedals to move the full range, forwards to shift up and
barkwards for down, with a range of 19.5-56 teeth.

This I have a picture of, if anyone is interested(but
cant host it)

Tokhiem made the something similar for the rear wheel

"Francesco Devittori" <frenkatfrenkdtcm> wrote in message
"]news:[email hidden]...

Quoted message said:

bfd said:

Quoted message said:

Francesco Devittori wrote:

However I'm still curious about alternative desings...

Why are you now questioning what's been in existence,
and proven, for easily over 100 years? Well, if you
really want *different* cranks, perhaps you can look for
a set of these to use:

PMP crankset:
classicrendezvous.comPMP main.htmOpen ↗

or how about a 10-arm Colnago design (scroll down to 3rd
photo): classicrendezvous.comCampagnoOpen ↗
lo/Campag_rare.htm

Maybe you can make this work:
classicrendezvous.comcheckered flag.htmOpen ↗

Unless someone will mathematically prove that the
current design is the most efficient, the lightest and
the most troublefree you can assume that a better
solution *could* exist.

Excuse me, but let's get this straight. YOU are the one
questioning whether the "efficiency" of today's cranks. I
would argue that it is YOU, not me or anyone else, but YOU
who must prove there is a *better solution*.

Where do you get off thinking that the current design is not
efficient. What proof do you have? Is it the fact that maybe
YOU are so out of shape that you can't climb a hill that you
now seek some sort of solution? Perhaps you're thinking that
with this *better* design that you will be able to keep up
with someone like say Lance Armstrong. Dream on buddy. Until
you can show evidence that the current design is insufficent
- and yes, we would want both your "mathematics" and
"physics" behind your claims, keep dreaming.....

bfd said:

"Francesco Devittori" <frenkatfrenkdtcm> wrote in message
"]news:[email hidden]...

Quoted message said:

bfd said:

>Francesco Devittori wrote:
>
>However I'm still curious about alternative desings...

Why are you now questioning what's been in existence,
and proven, for easily over 100 years? Well, if you
really want *different* cranks, perhaps you can look
for a set of these to use:

PMP crankset:
classicrendezvous.comPMP main.htmOpen ↗

or how about a 10-arm Colnago design (scroll down to
3rd photo): classicrendezvous.comCamOpen ↗
pagnolo/Campag_rare.htm

Maybe you can make this work: classicrendez-classicrendez-Open ↗
vous.com/USA/checkered_flag.htm

Unless someone will mathematically prove that the
current design is the most efficient, the lightest and
the most troublefree you can assume that a better
solution *could* exist.

Excuse me, but let's get this straight. YOU are the one
questioning whether the "efficiency" of today's cranks. I
would argue that it is YOU, not me or anyone else, but YOU
who must prove there is a *better solution*.

Where do you get off thinking that the current design is
not efficient. What proof do you have? Is it the fact that
maybe YOU are so out of shape that you can't climb a hill
that you now seek some sort of solution? Perhaps you're
thinking that with this *better* design that you will be
able to keep up with someone like say Lance Armstrong.
Dream on buddy. Until you can show evidence that the
current design is insufficent - and yes, we would want both
your "mathematics" and "physics" behind your claims, keep
dreaming.....

Biopace showed us that there is a better way. Hehe

<snip>

Quoted message said:

Excuse me, but let's get this straight. YOU are the one
questioning whether the "efficiency" of today's cranks. I
would argue that it is YOU, not me or anyone else, but YOU
who must prove there is a *better solution*.

Where do you get off thinking that the current design is
not efficient. What proof do you have? Is it the fact that
maybe YOU are so out of shape that you can't climb a hill
that you now seek some sort of solution? Perhaps you're
thinking that with this *better* design that you will be
able to keep up with someone like say Lance Armstrong.
Dream on buddy. Until you can show evidence that the
current design is insufficent - and yes, we would want
both your "mathematics" and "physics" behind your claims,
keep dreaming.....

Geez! Who [censored] in your wheaties this morning?

M

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

This I have a picture of, if anyone is interested(but
cant host it)

Send it to me. I'll put it up on my web site.
-------------
Alex

Alex Rodriguez <[email hidden]> wrote in message
news:<[email hidden]>... <snip>

Quoted message said:

Many years ago I remember seeing a similar device for
sale. It was slightly different. It used more than two
jockey wheels. Something like 6. They all were on radial
sliding tracks. When you shifted gears the wheels would
move in and out. I have no idea who well it worked.
----------------
Alex

There's been a couple versions of this- a plastic version
that appeared on the Yankee bicycle (I think) and an earlier
version (late 70's - early 80's) that was nearly solid
steel. Interesting idea- a truly continuously variable
transmission. It worked- but they required backpedaling to
downshift.

Here's another variation on crankset design:
web.uct.ac.zakdrive.htmlOpen ↗

Jeff

Francesco Devittori said:

I see racers that strip the paint off their frames to save
weight, I see others that drills holes everywhere (Mayo at
Ventoux TT for ex.) and looking at the crankset I wonder
if nobody tried something different than the traditional
design. What about two arms, each with a small wheel (like
the rear der. pulley)? One arm could change its angle to
get a lower/higher gear. No front der (some mechanism to
change that angle would be needed), no chainrings. Plus
the chain won't have to change ring => no risk of falling
down. frenk.comsilly.pngOpen ↗ (sorry for the crappy
drawing!)

Maybe it's a stupid idea, but I can't believe nobody tried
some alternative solution!

Francesco

Essentially you reinvented the Tokheim Transmission

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971

"SDMike" wrote: Geez! Who [censored] in your wheaties this
morning? ^^^^^^^^^^^^^ He may be using harsher words than
necessary, but he happens to be right. The things on a
bicycle that can be improved are changing: indexed shifting,
increased number and range of ratios, decreased
weight/improved materials, etc. Probably the reason that the
cranks have stayed the same is that they work so well, in
spite of their simplicity. If someone builds a "better
mousetrap," the cycling community will beat a path to
his/her door. It is not necessary to prove that improvements
are still possible. They prove themselves.

bfd said:

Why are you now questioning what's been in existence, and
proven, for easily over 100 years? Well, if you really
want *different* cranks, perhaps you can look for a set of
these to use:

Steady on. Cranks with funny bends in are snake oil, we
agree; you can't get out more power than you put in. But the
idea that some funky design might replace the need for a
front derailleur and multiple chainrings; that's not
inherently bogus, and that's what the guy's saying.
--
David Damerell <[email hidden]> flcl?

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

In article
<[email hidden]>,
[email hidden] says...

Quoted message said:

This I have a picture of, if anyone is interested(but cant
host it)

Send it to me. I'll put it up on my web site.

Go to columbia.eduCranksOpen ↗ to see
the pictures.
-------------
Alex