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.


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sig 56