program to compute gears, with table

On Saturday, September 9, 2017 at 8:59:58 PM UTC-4, Emanuel Berg wrote:
AMuzi wrote:

The guy who only stocks one model chain knows
a lot more than the guy who made it?

http://bike.shimano.com/content/saus...s/cn-hg40.html

... what do you mean? What I can see your link
say the same:

Cassette Compatibility 6/7/8-speed

--
underground experts united
http://user.it.uu.se/~embe8573

The link might say 6,7 & 8 speedbut Andrew'sright that the shiftingionthe6 speed will NOT beas good asit would be with a PROPER 6 speed chain. They will NOT work well if at all on 9,10 or 11 speed cassettes.

Cheers

In rec.bicycles.tech Joerg wrote:
:On 2017-09-08 12:59, David Scheidt wrote:
: In rec.bicycles.tech Joerg wrote:
: :On 2017-09-08 10:52, Emanuel Berg wrote:
: : Skip Montanaro wrote:
: :
: : * Why the 1.0 divisor when computing gear?
: :
: : As explained, otherwise it'll be integer
: : division. But I think that qualifies as a hack
: : (not an ugly hack tho) so there is no shame in
: : spotting it an "error"
: :
: : * You can skip the radius and use wheel
: : (diameter) directly in computing
: : the circumference.
: :
: : Right!
: :
: : * It never occurred to me to do this in Lisp.
: : I always just use an online calculator, like:
: :
: : http://www.gear-calculator.com/?GR=D...&SL=2.6&UN=KMH
: :
: : Let's agree there is no need to do it in Lisp.
: : Only a desire
: :
:
: :Why make things complicated? I do such stuff with spreadsheets. That's
: :what they were invented for. Part of every office software including
: :free ones.
:
: I rewrote his code in common lisp in less time than it takes excel to
: start.
:

:Wow, you must be able to type at hundreds of letter a second. Here, it
:takes less than 2sec for Excel to start. Mostly only a split second to
pen the file because I usually have it running nearly all the time.

On my mac at work, from the time I double click the excel icon to the
time it is ready to do work is over a minute. It's a modern machine,
running an old version of excel. The windows machine I have, but
never use, which is more powerful, and running a current version,
takes even longer. It does have a spinny disk, and not an ssd.
(that's not counting the time to takes to boot up, since it's off.)

--
sig 57

On Sat, 09 Sep 2017 12:37:07 +0200, Emanuel Berg
wrote:

John B. wrote:

The rear sprocket spacing is closer as the
number of cassette cogs goes up, so
narrower chains.

The over all length of the cassette is
limited by the distance between the rear drop
outs as the wider the cassette the more the
hub flange on that side must be offset and
thus the angle of the spokes decreases.

Okay? Is that the reason you simply cannot make
the back fork wider? At some point the spoke
angle will make for a wheel that isn't
strong enough?

Sure you can make it wider. In fact aren't MTB bikes wider.
But of course that means a wider crank to keep a decent chain line....

Or, you can just use a narrower chain :-)
--
Cheers,

John B.

On Sat, 09 Sep 2017 08:58:17 -0500, AMuzi wrote:

On 9/8/2017 4:23 PM, wrote:
On Friday, September 8, 2017 at 10:45:07 AM UTC-7, Emanuel Berg wrote:
Graham wrote:

So if your definition of gear is roll out in
mm then it looks close. Do not forget to
include the tyre.

Right, perhaps I should change "gear" into
"roll out" if that's the agreed-upon term.
Perhaps I should even make it print the
formulae first thing.

And I'll include the tyre. Excellent

There's always a slight error this way. The radius of a tire and hence it's circumference changes slightly with pressure and/or weight of the rider.


The ancient and traditional method from race-rules gear
limits to computer input is a rollout.
Ride over a spot of paint and measure between marks. In
theory it's 2R*3.14159. In practice it is not. As you note,
rider weight, inflation etc have some bearing on this

Disregarding "gear inches" I found a sequel to the Freakonomics book
called "SuperFreakonomics" It gets into the economics of street
prostitution early on in the book :-)
--
Cheers,

John B.

On Sat, 09 Sep 2017 18:40:25 +0200, Emanuel Berg
wrote:

AMuzi wrote:

Overall width. 4/5 speed systems used very
wide chain as you may recall. To get 8, 9,
10, 11 sprockets inside the 130mm road format
(originally seven speeds) the sprockets are
closer and so the chain is smaller.

Is it enough to count the sprockets,
e.g. does an 8 sprocket casette always have the
same width? Or does that vary
between manufacturers?

And surely there aren't different chains for
8, 9, 10, and 11 casettes, i.e. four different
chain sizes?

You'll have to ask Andrew for complete details but from my own use 9
and 10 speed cassettes are the same width. Or perhaps better to say
that I've interchanged them with no problems.
--
Cheers,

John B.

On Sat, 09 Sep 2017 12:40:44 -0500, AMuzi wrote:

On 9/9/2017 11:40 AM, Emanuel Berg wrote:
AMuzi wrote:

Overall width. 4/5 speed systems used very
wide chain as you may recall. To get 8, 9,
10, 11 sprockets inside the 130mm road format
(originally seven speeds) the sprockets are
closer and so the chain is smaller.

Is it enough to count the sprockets,
e.g. does an 8 sprocket casette always have the
same width? Or does that vary
between manufacturers?

And surely there aren't different chains for
8, 9, 10, and 11 casettes, i.e. four different
chain sizes?


Surely you jest!
There are variants within each format. Plus 12 speed now.
Four chain models is not a shop inventory - it's nothing.

Out of curiosity are single speed bikes doing back there in the world.
Here, I would guess, that they outsell the multi speed bikes.

When I get up early and am out on the road at 6ish when the
neighborhood ladies are out doing the days shopping I've yet to see a
multi speed bicycle.
--
Cheers,

John B.

On 2017-09-09 19:06, David Scheidt wrote:
In rec.bicycles.tech Joerg wrote:
:On 2017-09-08 12:59, David Scheidt wrote:
: In rec.bicycles.tech Joerg wrote:
: :On 2017-09-08 10:52, Emanuel Berg wrote:
: : Skip Montanaro wrote:
: :
: : * Why the 1.0 divisor when computing gear?
: :
: : As explained, otherwise it'll be integer
: : division. But I think that qualifies as a hack
: : (not an ugly hack tho) so there is no shame in
: : spotting it an "error"
: :
: : * You can skip the radius and use wheel
: : (diameter) directly in computing
: : the circumference.
: :
: : Right!
: :
: : * It never occurred to me to do this in Lisp.
: : I always just use an online calculator, like:
: :
: : http://www.gear-calculator.com/?GR=D...&SL=2.6&UN=KMH
: :
: : Let's agree there is no need to do it in Lisp.
: : Only a desire
: :
:
: :Why make things complicated? I do such stuff with spreadsheets. That's
: :what they were invented for. Part of every office software including
: :free ones.
:
: I rewrote his code in common lisp in less time than it takes excel to
: start.
:

:Wow, you must be able to type at hundreds of letter a second. Here, it
:takes less than 2sec for Excel to start. Mostly only a split second to
pen the file because I usually have it running nearly all the time.

On my mac at work, from the time I double click the excel icon to the
time it is ready to do work is over a minute. It's a modern machine,
running an old version of excel.


I suggest you use a PC instead, and a contemporary one. If it was more
than a couple of seconds I'd be concerned about something not being
right with the computer.


... The windows machine I have, but
never use, which is more powerful, and running a current version,
takes even longer. It does have a spinny disk, and not an ssd.
(that's not counting the time to takes to boot up, since it's off.)


Looks like your computers need some serious clean-up. I just tried it on
mine (Dell XPS8700, no SSD, regular HD). It takes such a small fraction
of one second that it is impossible to gauge the milliseconds from click
to Excel being open. I would need a camera and count the frames.

--
Regards, Joerg

http://www.analogconsultants.com/

On Friday, September 8, 2017 at 9:47:02 PM UTC-7, Emanuel Berg wrote:
John B. wrote:

"well, we do still have a few 9 speed chains
left".

Anyone feel free to elaborate on this. How and
why should the chain be different with
different cassette/chainring configurations?

And is there a "notation" do describe this?
Usually makes it easier to understand...

The spacing between the cogs grows narrower with growing numbers of gears and since they have pick-ups to assist shifting you have to make the chains narrower to keep them from hopping gears all the time.

John B. wrote:

Out of curiosity are single speed bikes doing
back there in the world. Here, I would guess,
that they outsell the multi speed bikes.

When I get up early and am out on the road at
6ish when the neighborhood ladies are out
doing the days shopping I've yet to see
a multi speed bicycle.

Very common here as well but I make no big
distinction between the single speed, 3-speed
or even the Pentasport Torpedo, which is much
less common of the three. MTBs and racers and
shoppers with casettes are not uncommon but it
varies with age and gender, and with the ladies
in particular they are in the minority.

--
underground experts united
http://user.it.uu.se/~embe8573

The spacing between the cogs grows narrower
with growing numbers of gears

Are the sprockets always the same width, only
spacing grows narrower?

and since they have pick-ups to assist
shifting you have to make the chains narrower
to keep them from hopping gears all the time.

Does it impact anything else in the cycling
experience/performance to have
a narrower chain?

--
underground experts united
http://user.it.uu.se/~embe8573