Originally Posted by
FBinNY
Bikes do vary, and I should have added "usually" in the statement. But the point remains that as side flexibility increases the ability of the jockey wheel to push the chain over as you shift.
Absolutely.
Originally Posted by
FBinNY
Yes, though load may be too strong a term because there's close to zero tension in the lower loop.
Could you clarify what you mean by the lower loop? Anything lower than the sprocket (as the 'returning' part of the chain that does not carry any pedaling load), or do you differentiate between the 'loops' the chain makes around the 2 RD jockey wheels?
Originally Posted by
FBinNY
Rather than look at cross chaining as a black and white issue, I prefer to think of in shades of gray, there are aligned sprocket pairs, then others that are mis-aligned by varying amounts.
Yes, absolutely.
Originally Posted by
FBinNY
The express purpose of any lubricant is to prevent metal to metal contact. When that happens the lubricant has failed.
Originally Posted by
FBinNY
The ability of a lube to prevent metal/metal contact depends on it's film strength, and the pressure pressing the two parts together. Thinking in bike chain terms, a lube that's perfectly OK spinning along at a moderate pace in the flats, may be inadequate for the higher chain tension when pounding up steep hills. The lubes ability to replenish itself in the working area is also a key factor, as it's constantly being forced away from the point of contact.
There is a ton of literature on the subject. Search using key words like "lubrication science" or "bearing lubrication" or "plain bearing lubrication" You'll have enough reading to keep you busy for a couple of years.
I do have a basic understanding of tribology, although it is slightly rusted. (Pun intended). However, I fail to find specifics on bicycle chains, which differ considerably from motorcycle chains. So if it's not too much trouble, I'd like to repeat my question: Would a good bicycle chain, new, grit free have any metal-to-metal contact in its bearings under load? (thinking hill climbing out of the saddle).
If not, where does the black stuff come from, that on a new chain develops within less than a 100 miles, and which very clearly comes from the inside? I had always taken that to be metal abrasion remnants...
Thanks for your patience.