2/27/14 10:52 AM

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But does the big-big combo rubs (makes noise)? If not, does it REALLY wear the chain more?

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2/27/14 1:55 PM

quote:

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But does the big-big combo rubs (makes noise)? If not, does it REALLY wear the chain more?

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3/6/14 6:08 PM

" ...Yes it does. Chains are designed to run in a completely straight line which is why industrial chains are laboriously aligned and why single speed chains, if set up correctly, last so long. Any deviation from that straight line wears the chain faster and big-big is the most serious misalignment. Small-small has alignment problems too but, as you notice, it often makes other noises so you don't stay in it much."

As far along as chains have evolved, I'd have to say that modern chains are specifically designed to run at the whole range of angles that a bike can be shifted into, except for the useless small-to-small combination that has the chain rubbing on adjacent, larger ring(s).

This began in earnest when bushing chain became bushingless, allowing each inner plate with their own (now very narrow) bushings to shift alongside the paired inner plate to apply tension nearer to both ends of the pin, instead of a friction-addled push-and-pull binding on the pin.
It also allowed the inner and outer sideplates to maintain less-forceful contact with one another, further lowering friction and lubrication requirements.

While I usually try to maintain a reasonable chainline in any longer-duration selection of gear, I also use the big ring nearly all of the time except on steeper grades. Only when a crossed gear would be used for an extended period would I find it worthwhile to shift down in front, but I can't say how my energy economy or my chain wear economy are actually effected by my choice of gear, other than that I avoid the momentum-robbing front downshift when staying in the bigger ring seems to get me over the hill faster.

I usually break in new chain and sprockets by riding forcefully uphill in the fully-crossed big-to-big combination, my feeling being that it is better to force conformity between all the rubbing surfaces before a new chain becomes contaminated with grit. More of a subtle burnishing and cold-working of wear surfaces than of simply wearing them away with abrasive dust.
The aggressive break-in does seem to immediately improve the smoothness of cross-chain transmission, and my chain measurements show absolutely no measurable increase in chain "stretch" wear because of it.

Modern chain is amazing stuff, all the design, metallurgy and process steps that go into it.
Especially the very scant lubrication that is required today, such that a well-maintained chain can be very clean just from wiping with good terrycloth and with occasional very light application of lube.