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.
http://www.frenk.com/silly.png
(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.
http://www.frenk.com/silly.png
(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.
http://www.frenk.com/silly.png
(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:
http://www.classicrendezvous.com/Italy/PMP_main.htm

or how about a 10-arm Colnago design (scroll down to 3rd photo):
http://www.classicrendezvous.com/Italy/Campagnolo/Campag_rare.htm

Maybe you can make this work:
http://www.classicrendezvous.com/USA/checkered_flag.htm

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:
http://www.classicrendezvous.com/Italy/PMP_main.htm

or how about a 10-arm Colnago design (scroll down to 3rd photo):
http://www.classicrendezvous.com/Italy/Campagnolo/Campag_rare.htm

Maybe you can make this work:
http://www.classicrendezvous.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.
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.
http://www.frenk.com/silly.png
(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:
http://www.classicrendezvous.com/Italy/PMP_main.htm

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):
http://www.classicrendezvous.com/Italy/Campagnolo/Campag_rare.htm

Looks like a photoshop special, not a real crank.

Quoted message said:

Maybe you can make this work:
http://www.classicrendezvous.com/USA/checkered_flag.htm

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: 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.

"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.

"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.
http://www.frenk.com/silly.png
(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:
http://www.classicrendezvous.com/Italy/PMP_main.htm

or how about a 10-arm Colnago design (scroll down to 3rd photo):
http://www.classicrendezvous.com/Italy/Campagnolo/Campag_rare.htm

Maybe you can make this work:
http://www.classicrendezvous.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.....

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:
http://www.classicrendezvous.com/Italy/PMP_main.htm

or how about a 10-arm Colnago design (scroll down to 3rd photo):
http://www.classicrendezvous.com/Italy/Campagnolo/Campag_rare.htm

Maybe you can make this work:
http://www.classicrendezvous.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:
http://web.uct.ac.za/depts/psychology/bok/kdrive.html

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.
http://www.frenk.com/silly.png
(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 http://www.columbia.edu/~adr5/pictures/Cranks/ to see the pictures.
-------------
Alex