Electronic shifting system

Tom Kunich wrote:
"Bret" wrote in message
oups.com...
On Aug 10, 8:38 pm, "Tom Kunich" cyclintom@yahoo. com wrote:

And aside from the fact that you don't understand the cost of
electronics
these days, there's no way that you can make an electro-mechanical
shifter
as cheaply as a mechanical one

Why do you believe electronics are expensive? Are you talking about
the cost of ASICs? There are alternatives you know.

Bret - what is the power costs to run a stepping motor mechanism strong
enough to shift and maintain positioning of a chain on a bicycle for the
length of one day?


what is the power cost of running a headlight for one night?

Tom Kunich wrote:

"lightninglad" wrote in message
ups.com...

Perhaps you're suggesting that there might be some method of detecting
whether or not the chain is centered.

Ah yes...spoken like a true engineer...

Well, here's some thoughts. A badly aligned chain is noisy - detecting
that should be simple enough and in fact it's already done to detect
bearing wear in inductrial machinery. Next....?

Electro mechanical devices can be cheaper than pure mechanical devices
if the electro mechanical device IS self adjusting - because you can
build a cheap mechanism with (releatively) poor tolerances and have
the computer adjust it.

If electro mechanical chip driven computerised machinery is more
expensive, why have all the domestic appliances gone to a direct drive
motor and a computer chip?

You obviously have a brilliant future in engineering. What is it that
you do again?


ad hominem.

fact is, proximity detection is old hat. that crappy old /cheap/ inkjet
printer on your desk fully self-calibrates each time you switch it on.
just because /you/ may not be familiar with these design solutions
doesn't mean they don't exist!

I'm curious whether the posters who have actually used the Mectronic
agree that it was remarkably reliable when shifting under load? I'm
trying to get my mind wrapped around that. The Mavic derailleur does
not look sophisticated enough to time the cogs. Possibly an overshift
and return that was more consistent than the "analogue" method built
into SIS would do it, but I wonder...

JG

JG wrote:
I'm curious whether the posters who have actually used the Mectronic
agree that it was remarkably reliable when shifting under load?

what, criticism of something they've never tried??? say it ain't so!


I'm
trying to get my mind wrapped around that. The Mavic derailleur does
not look sophisticated enough to time the cogs. Possibly an overshift
and return that was more consistent than the "analogue" method built
into SIS would do it, but I wonder...

JG


agreed - from what i can see, there's no "self-adjust" built into this one.

JG wrote:
I'm curious whether the posters who have actually used the Mectronic
agree that it was remarkably reliable when shifting under load? I'm
trying to get my mind wrapped around that. The Mavic derailleur does
not look sophisticated enough to time the cogs. Possibly an overshift
and return that was more consistent than the "analogue" method built
into SIS would do it, but I wonder...

For race sized cassettes, shifting isn't all that difficult given modern
chain and tooth forms, floating top pulley and slant-body changers
with dual springs. You may need something more complex for an 11~34 with
a tandem-range triple crank but race bikes aren't that.

Mektronic performed as advertised, RF problems and moisture were it's
weak spots.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

in message .net, Tom
Kunich ('cyclintom@yahoo. com') wrote:

"Bret" wrote in message
oups.com...
On Aug 10, 8:38 pm, "Tom Kunich" cyclintom@yahoo. com wrote:

And aside from the fact that you don't understand the cost of
electronics these days, there's no way that you can make an
electro-mechanical shifter
as cheaply as a mechanical one

Why do you believe electronics are expensive? Are you talking about
the cost of ASICs? There are alternatives you know.

Bret - what is the power costs to run a stepping motor mechanism strong
enough to shift and maintain positioning of a chain on a bicycle for the
length of one day?

What is the need to run a stepper motor when you're sitting on top of a
jockey wheel being powered by 0.4Kw of cyclist, and which power you can
tap just by releasing a clutch?

The power is there for the asking. All you need to do is to control when to
ask it. The power needed by the control electronics can be in terms of
fractions of a watt, and that too can be derived directly from the chain
without need for anything more than a capacitor to buffer the power.

Yes, pulling a little bit of power out of the drive train to run the
electronics is not zero-cost, but jockey-wheels are not exactly friction
free anyway.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

Wise man with foot in mouth use opportunity to clean toes.
;; the Worlock

in message , jim beam
') wrote:

JG wrote:
I'm curious whether the posters who have actually used the Mectronic
agree that it was remarkably reliable when shifting under load?

what, criticism of something they've never tried??? say it ain't so!

Well, I'll admit I've never tried it - but I've got an ebay automatic watch
set in case one ever comes up.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; have mercy on the slender grass

"jim beam" wrote in message
...
Tom Kunich wrote:
"jim beam" wrote in message
...

eh? if you can have the kind of proximity detector that cars use for
antilock brakes, or even detect fingers on mousepads, why can't you
detect the position of 10 disks with nice convenient pulse fingers on
them?

What exactly does this have to do with detecting whether a flayling chain
is centered on the cog in the small middle or large ring?

eh? a conventional derailleur doesn't do that. and an indexed derailleur
/can't/ do that.

Psst - they don't NEED to do that. Again, WHAT are you gaining if you go to
electronic shifting?

Please explain to us what sort of clearances are in today's 10-speed
setups.

red herring.

I didn't expect you to understand the problem and you just proved it.

but you have that same issue with cars. even donuts on mousepads.

You really don't understand what you're talking about.

yes i do. you were bleating about ability to detect proximity. in both
the above examples, solutions are cheap and robust. just like would be
required for a derailleur.

No - YOU were bleating about "self adjusting". Proximity has nothing to do
with that but you aren't able to understand the problem from an engineering
perspective.

who said that? besides, bikes are limited to the uci limit in
competition, but can be made much lighter.

Where are you getting the idea that bikes can be "much lighter"? Maybe
you've missed the fact that today's bicycle can dissolve at the drop of a
hat.

ok, now you're becoming irrational.

You are the one that hasn't a clue of the world around you. Perhaps you
ought to learn something before pretending you know about it.

As I pointed out in early July, I was riding with a guy who hit a dog - a
young medium sized Labrador Retriever. The dog ran away complete unhurt
while the front fork and headtube on his Parlee broke off cleanly and he
went down and broke his neck in two places. Luckily he is OK but if
you're suggesting there's some sort of excess strength somewhere in a
bicycle you're misled.

weight != strength. red herrings about alleged crash injuries have
NOTHING to do derailleurs or mechanism weights.

Perhaps you can explain that?

Tom Kunich wrote:
"jim beam" wrote in message
...
Tom Kunich wrote:
"jim beam" wrote in message
...

eh? if you can have the kind of proximity detector that cars use
for antilock brakes, or even detect fingers on mousepads, why can't
you detect the position of 10 disks with nice convenient pulse
fingers on them?

What exactly does this have to do with detecting whether a flayling
chain is centered on the cog in the small middle or large ring?

eh? a conventional derailleur doesn't do that. and an indexed
derailleur /can't/ do that.

Psst - they don't NEED to do that. Again, WHAT are you gaining if you go
to electronic shifting?

psst - in what way could a properly designed self-adjusting system
possibly shift worse than a manual system?


Please explain to us what sort of clearances are in today's 10-speed
setups.

red herring.

I didn't expect you to understand the problem and you just proved it.

it's not a clearance issue guy!!! it's an issue of determining basis
coordinates and positioning accordingly. a red herring is still a red
herring regardless of specious allusions.


but you have that same issue with cars. even donuts on mousepads.

You really don't understand what you're talking about.

yes i do. you were bleating about ability to detect proximity. in
both the above examples, solutions are cheap and robust. just like
would be required for a derailleur.

No - YOU were bleating about "self adjusting". Proximity has nothing to
do with that but you aren't able to understand the problem from an
engineering perspective.

you really don't get it. if you wanted a self-adjusting system, you'd
/have/ to detect proximity. duh.


who said that? besides, bikes are limited to the uci limit in
competition, but can be made much lighter.

Where are you getting the idea that bikes can be "much lighter"?
Maybe you've missed the fact that today's bicycle can dissolve at the
drop of a hat.

ok, now you're becoming irrational.

You are the one that hasn't a clue of the world around you. Perhaps you
ought to learn something before pretending you know about it.

er, perhaps you're looking in a mirror when saying that?


As I pointed out in early July, I was riding with a guy who hit a dog
- a young medium sized Labrador Retriever. The dog ran away complete
unhurt while the front fork and headtube on his Parlee broke off
cleanly and he went down and broke his neck in two places. Luckily he
is OK but if you're suggesting there's some sort of excess strength
somewhere in a bicycle you're misled.

weight != strength. red herrings about alleged crash injuries have
NOTHING to do derailleurs or mechanism weights.

Perhaps you can explain that?

sure - it's easy. weight != strength! you say you're an engineer, right?

"Simon Brooke" wrote in message
...
in message .net, Tom
Kunich ('cyclintom@yahoo. com') wrote:

Bret - what is the power costs to run a stepping motor mechanism strong
enough to shift and maintain positioning of a chain on a bicycle for the
length of one day?

What is the need to run a stepper motor when you're sitting on top of a
jockey wheel being powered by 0.4Kw of cyclist, and which power you can
tap just by releasing a clutch?

Maybe you missed the resident genius Kveck telling us that there wasn't any
clutches in the Mektronic.

The power is there for the asking. All you need to do is to control when
to
ask it.

Indeed but the group was talking about using a stepping motor to precisely
position the RD so that they wouldn't have to turn the adjusting screw a
quarter turn once a year between tune-ups.

Simon, it is apparent that you have some education in mechanical design.
This whole argument began when I said that there wasn't anything to GAIN by
going to electronic shifting. It's only another failure point in an
otherwise highly reliable machine. But jim beam (named apparently from what
he is under the influence of ) seems to believe that derailleurs which are
almost the perfect mechanism, can be markedly improved with electronics.

The power needed by the control electronics can be in terms of
fractions of a watt, and that too can be derived directly from the chain
without need for anything more than a capacitor to buffer the power.

Well, not quite but I agree that you don't need a lot of power if you're
willing to rob most of it from the drive train. But then you're either stuck
with the Mektronic mechanism which has fixed stops or complex sensors and
micro-adjustable position sensors which in the end would be quite a pain in
the neck without adding anything to reliability, reducing costs or weight.

The modern bicycle is the end result of a hundred and fifty years of
evolution. It achieved it's peak in the 1960's and everything added since
then has been only for performance on smooth roads.

It is possible to build reliable carbon bikes but not with a significant
reduction in weight. That isn't to say that there aren't certain advantages
to carbon bikes but there are significant disadvantages as well. It is
pretty difficult to beat a good well designed steel bike from Bob Jackson or
Waterford. (Queue in Donnelly's calculation showing that the difference in
weight can save 2 seconds on the Stelvio.)