Re: Extensive article on Rivendell and Grant Petersen

Am Tue, 24 Sep 2024 10:55:07 -0400 schrieb Frank Krygowski
<frkrygow@sbcglobal.net>:

On 9/24/2024 10:15 AM, Wolfgang Strobl wrote:

 
I wasn't confused by those three front chaingrings on the bike a local
shop built for me in 1996...
 
But I certainly learned to dislike its many weaknesses.
 
 

As a
bonus, most with >1 chainring get more gear range than they'd otherwise
have, and without resorting to unusual or proprietary equipment.

 
I wouldn't call what Shimano and SRAM sell for ordinary road bikes or
MTB for quite some time now "unusual" or "proprietary".  There is the
usual fight about patents, but that's about it.
 
Anyway. Those two bikes that I built for my wife and me in early 2023
<https://www.mystrobl.de/ws/pic/fahrrad/20240624/P1107879.jpg>
got a single narrow/wide chainring and a gear range of 10:52. ...
 
She likes it and so do I. I'm grateful to have finally got rid of the
misconstruction called a front derailleur. That radio-controlled
electric gearshift works like charm, too.

>
My touring bike matches your gear range: 19 inch low, 100 inch high
gear.

A little bit more gear range than ours, 1:5.26, yes. But see below.

My bicycle initially had a 46 teeth chainring, when I bought the
components in early 2023, but I replaced that by a 40 teeth chainring
immediately and then again by a 38T one in summer this year. 


My wife got a SRAM Rival AXS DUB Wide Powermeter 1x12-speed Crank 40T,
because that was available then and because she didn't have a
powermeter, yet. Her chainring got replaced with an 32 teeth one, in
summer.

For those bikes I get these numbers (Entfaltung on the left, gearinch on
the right):

Chainring 46T
  1.88 m -  9.80 m       24 -  123 inch

Chainring 40T
  1.64 m -  8.52 m       21 -  107 inch

Chainring 38T
  1.56 m -  8.09 m       20 -  101 inch

Chainring 32T
  1.31 m -  6.82 m       16 -   85 inch


In short, I'm able to shift that 1:5.2 range for quite an amount, simply
by replacing that single chainring, and already made use of that.

(For the uninitiated, those are equivalent wheel diameters.) All
done with very conventional equipment, stuff available in the mid-1980s.

You're still riding that bicycle built in the mid-1980s? ;-)

I'd really like to know what chainrings and cassettes you've got, for
tha.   My wife and I both bought a randonneur style bicycle in 1978.
<https://www.mystrobl.de/ws/fahrrad/peugeot/index.htm>

2 x 5 gears, 38 x 48, 14x17x20x23x26

Peugeot

Chainring 48T
  3.93 m -  7.30 m       49 -   92 inch

Chainring 38T
  3.11 m -  5.78 m       39 -   72 inch

In combination, that's 39 - 92 inch, a lot less than 19-100 inch. That's
about half as much as what we have now.

AFAIR there wheren't derailleurs available offering  more capacity at
that time. At least not conventional equipment available everywhere.

>
I'm not sure what you consider "many weaknesses."

The most relevant weakness of the front derallieur is the very fact that
it exists at all.  Eliminating one of two roughly similar mechanical
components eliminates roughly half of what can and will break and will
need service.   Of course, oldtimers like us have learned and memorized
complicated gearing patterns, when to use what chainring and how.
Remember shifting patterns and halfstep vs crossover?   Fun fact: the
electronic shifters from both Shimano and SRAM are able to automate most
of that, converting a 2 x 12 gearing into a 1 x 12 one. Of course,
that's an opportunity for yet another dispute: when to enable that
feature and when not.

I could add various anecdotes about what got wrong during those fifteen
years when this bike,
<https://www.mystrobl.de/Plone/radfahren/IMG-2461.jpeg>
which was originally purchased for a multi-week cycling trip with the
whole family and friends through northern Germany, was mostly used for
commuting, throughout the year, whether it was raining or snowing, on
roads that where often covered with a mixture of salt, sand and mud
sometimes for months.  A front derallieur with a triple chainring works
quite well when it is new and for quite a while, if you clean it after
each ride, but it has many ways to fail in a lot of funny or not so
funny ways, if you do not. Often, there just isn't time for that, if you
have a family and a long commute. 

I managed it all, frequently adjusting the gears, cleaning, lubricating
and replacing chainrings, chain and cassettes, but it wasn't fun and the
front part of the gears was responsible for too much of the inevitable
hassle.  If you don't shift much and the triple combination only serves
the purpose of being able to ride both through the Alps and on flat
terrain when traveling with luggage, this may not be much of a problem.
However, I had to shift gears a lot under load in heavy rush-hour
traffic on my commute - and it was obviously not made for that. 

But I value the fact
that if a problem arises with shifting, I can diagnose it visually and
fix it. I'll never be able to do that with a radio link, and probably
not even with wired electronic shifting.

This ship has sailed.  I couldn't diagnose and fix that mechanical brake
shift lever (Shimano st-5703 ultegra) that broke in 2019, a few days
befor our departure itto our holidays, either. Often, replacing some
overly complex mechanical device by some mechatronics does make it
simpler and more robust.

>
Same with brakes, BTW. As mentioned, I fixed a brake clearance problem
on a friend's bike last week, one that required disassembling her brake.
If a similar problem occurred with a disc brake, I'd have been reluctant
to disassemble.

IMHO, this is a false dichotomy.  Outside of schools, research
institutions or while playing Robinson Crusoe, your rarely build your
stuff out of raw materials and from first principles.   You build it
from parts that got produced by a long chain of industries and
merchants, some purely mechanical, some just some microelectronics and
wires, some hybrid. Where the dividing lines are often has historical
reasons or is pure coincidence, regardless of whether the parts are
mechanical or not.

I dislike black boxes with hidden functions. And I tend
to disbelieve the sales pitch "But nothing will ever go wrong with this
system!"

Sure. So do I.  But I'm quite sure that a simple switch using  a low
power radio signal to communicate with a derallieur that is essentially
reduced to a sealed microcontroller operating a single actuator has a
lot less failure points than a mechanical Rube Goldberg device that has
to fit into a brake lever and has to communicate by a degrading wire
rope running over several corners, merging both control and power into
that single, unreliable channel.


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