Drive train/gearing changes

[staehpj1]

> That theory makes no sense, let me explain.

All of that may be so, but...

It seems to me that if the chain were to kink when it broke or even if the pin just popped out of the plate on one side of the link first before breaking completely (likely) it would cause the force applied to the cog to be at an angle.  The cogs can take a lot of force applied by the chain when applied perpendicular to the axle, but much less if at an angle.

If the chain kinked really badly it could even hit the cog next to the one that it was on applying lateral force which could possibly cause or contribute to the failure.

Maybe in some failure mode the chain may even manage to jam between cogs and bend a cog.

I don't know if any that is what happened, but it seems quite possible and maybe even likely that a chain failure could possibly lead to a bent cog.

[DaveB]

A bicycle is a machine of torque amplification, not horse power

Actually that isn't correct.  A bicycle is a distance amplification machine at the expense of torque. The bike travels further than your feet do even in very low gears.

Even if the chain broke first it would continue to follow through the stroke until it reached it's last link as a single unit.

That's not true either.  A popped pin or bent side plate could easily get jammed into the adjacent cogs and do all kinds of damage as it passed through the cassette.  I've seen rear derailleurs destroyed when a broken chain was pulled through them so a broken chain is not smooth and snag-free.  

[whittierider]

Yet another problem with the same post:

(The average human only develops about 1/8 of a horse power).

Um...average? Perhaps; but cyclists are not average.  1/3 horsepower for an hour is not uncommon for avid, fit cyclists.  Professional racers can put out 2/3 of a horsepower for an hour (at the end of a 150-mile race stage), and sprint at 2hp (1500 watts).  In adventure cycling, we're not interested in racing, but being able to make quick work of the mountain passes sure makes the trip more fun.