Chain Question

n crowley said:

Engineers discovered that two factors were important to the efficiency
of
the chain, the size of the sprocket and tension in the chain; the
larger the
sprocket and the higher the tension, the more efficient the chain.
From a standing start in a 4k Pursuit, when a rider applies that first
maximum
crank pressure, how is that force distributed between the sprocket
teeth in
contact with the chain ?

IIRC the first couple of teeth take most of the load. You can prove
this to yourself the next time you remove a fixed sprocket using a
chainwhip. The chain simply falls off the last few teeth of the
sprocket even when you're leaning on the handle of the whip - and this
is with a new sprocket.

n crowley said:

Engineers discovered that two factors were important to the efficiency
of
the chain, the size of the sprocket and tension in the chain; the
larger the
sprocket and the higher the tension, the more efficient the chain.

I thought it was lower tension -> more efficient. Less friction at the
pins or some such. All else being equal, larger sprockets -> lower
tension.

Jim Smith said:

I thought it was lower tension -> more efficient. Less friction at the
pins or some such. All else being equal, larger sprockets -> lower
tension.

I think I saw the same website. Presumably they were looking at it from
the POV of a singlespeed/fixed transmission where the chain tension is
adjustable. I think the theory is that a tighter chain doesn't waste
energy by sagging (i.e. flexing) on the two runs between sprocket and
chainring.

The most surprising finding was that an unlubricated chain is nearly as
efficient as a lubricated one (although it's noisy and presumably wears
very fast). I'm not as surprised by the lack of any real performance
difference between lubricants.

"Zog The Undeniable" wrote: IIRC the first couple of teeth take most of the
load. You can prove this to yourself the next time you remove a fixed
sprocket using a chainwhip. The chain simply falls off the last few teeth
of the sprocket (clip)
^^^^^^^^^^^^^^
Unless it is a homemade chainwhip, the chain will not be worn. Any time the
chain is less worn than the sprocket, it will have a shorter pitch than the
sprocket, which tends to place the load on the first tooth or teeth. As a
chain wears, it distributes the load more evenly. If a worn chain is mated
to a new sprocket, the longer pitch tends to load the teeth that are just
going out of mesh.

Leo Lichtman said:

Unless it is a homemade chainwhip, the chain will not be worn. Any time the
chain is less worn than the sprocket, it will have a shorter pitch than the
sprocket, which tends to place the load on the first tooth or teeth. As a
chain wears, it distributes the load more evenly. If a worn chain is mated
to a new sprocket, the longer pitch tends to load the teeth that are just
going out of mesh.

This was with a new sprocket and an admittedly home-made chainwhip, but
using virgin chain. Incidentally, the sprocket was an E.A.I. steel 18T
which is supposed to be of very high quality.