What's the loss of effective output, with a worn chain?

Question

I was just bought a new fine ultegra chain for 10 speed road race bike. This is actually the first new chain for this not so old bike. I am a fan of statistics, measuring power with a power unit on my time trial bike, and so on.

Let's focus on this worn chain.

It ran for about 1000km, so worn you nearly can do a 270-360 degree bow with it. How much effect are you losing between a completely new chain and a worn but (which is the point of comparison) accurately cleaned and re-oiled chain?

I mean, look at a cleaned oiled chain, fitting well with the current sprockets and not skipping cogs. Where is the power going away against a new firm, chain?

How do I measure?
Can I proof any other important winnings?

And (which I may have to point out) together with which kind of use.. I mean, the differences in a low-efficient 200km tour may be negligible compared to a 30km Time Trial where one may average 350 watt in 40 minutes.

Answer 1

This extensive IHPVA article about chain drive efficiency shows a model of how you might empirically test the losses, and describes the efficiencies of a new chain. Their test suggests that lubrication and chainline matter very little, while chain tension is of significant importance.

Answer 2

From a practical standpoint I suspect you're losing very little efficiency with a moderately worn chain. However, a more severly worn chain (usually at 2-3 times the distance you have on yours) will begin to cause abnormal wear on the sprockets, ultimately damaging them to the point where sprocket replacement is required. And of course, beyond a certain point the chain will skip and shift poorly.

However, if you were to measure very carefully you probably could detect some slight additional friction due to the increasingly poor fit between chain and cog tooth. The teeth are very carefully designed to engage the chain evenly, and a worn chain will cause additional friction as the chain slides onto the drive sprocket or off the driven sprocket.

Answer 3

The only significant loss of efficiency comes at the point wear the wear causes the chain to skip, in terms of power efficiency.

In addition, efficiency(time) lost to poor shifts and delays of that sort are a risk. But until the point where damage is affecting your ride is beyond the point where the chain has begun damaging the cassette and chain rings, and so your loss of financial efficiency comes much earlier.