Something I've been wondering about.

On 2019-03-19 14:16, David Scheidt wrote:
Joerg wrote:
:On 2019-03-19 05:37, AMuzi wrote:
: On 3/19/2019 6:32 AM, John B. Slocomb wrote:
:
: Last Sunday I was on my usual weekly "long ride" (which was hardly as
: long as it used to be). And I was sort of looking down and the chain
: was on the big chain ring and the 5th cassette sprocket (9 speed
: cassette) and I got to thinking.
:
: Note the friction losses for a chain drive are usually considered to
: be very low, the usual efficiency of a chain drive is usually reckoned
: to be "up to" 98%. But the instructions for installing a chain drive
: is always to ensure that the drive and driven sprockets are exactly in
: line.
:
: But the conventional bicycle with it's multiple front and rear
: sprockets does not have the sprockets aligned except in two instances,
: assuming the usual chain line dimensions. When on the large front
: chain ring and (usually) the center cassette sprocket on an uneven
: numbered cassette, and when on the small front chain ring and a larger
: cassette sprocket. Perhaps two sprockets larger than center.
:
: So, if the usually chain efficiency figures are used the chain is
: delivering the 98%+ efficiency only twice in a possible 18 speed
: range.
:
: What efficiency is being delivered during the periods when the chain
: is not perfectly aligned?
:
: And should one worry about it?
:
:
: Classic chain is roller chain and yes those run dramatically worse when
: chainline is askew. But after Sedisport, modern derailleur chain has
: interrupted sideplates with no full roller so they are quite forgiving
: of misalignment or, viewed another way, better shifting on derailleur
: systems. One downside is much faster wear but since they are relatively
: cheaper to make, we just throw them out sooner.
:
: I don't know the numbers for efficiency of derailleur chain at various
: angles but I think you're right although it may well be a reasonable
: tradeoff for other features.
:

:The Sachs-Sedis chains were the best and longest lasting I ever had on
:the road bike. The bad news is that I used up my last one in 2018 :-(

:As for cheaper, I don't think that's true. A good KMC 7-speed costs
:around $20. The Sachs-Sedis used to retain for $5-6 which would probably
:be $12-23 in today's Dollars.

KMC Z 72 is $10 at the LBS. Work great for 8 pseed and down.


Thanks, duly noted in the bike wiki file. That is a very good price.

Though the other reason why I prefer longer lasting parts is
environmental. We can't put spent bike chains in the recycling bin here.
They have to go into the regular household trash, with oil and all on there.

--
Regards, Joerg

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