O-ring chain

I believe that quoting a generic percentage BHP loss through a chain is wrong. If you think about it, a stiff chain will consume some power to turn it, lets assume it consumes 2bhp for arguments sake. This 2bhp consumption has no relevance to the power potential of the engine. Meaning that a 20bhp engine and a 100bhp engine will both 'lose' 2bhp.

Percentages only come into the conversation when looking at how much of the engines power has been 'lost' in this way. Which, on our hyperthetical engines above, would be 10% and 2% respectively.

Nigel, that makes sense. For the coasting test the chain doesn't care if the engine in the bike is a 25 HP ES2 , 60 HP Commando, or a 250 HP gp bike.
Where the HP or the engine does have an effect on chain power loss is when that horsepower is in use. As tension in the chain increases from the horsepower being produced, so will resistance and therefore power losses. This would be the pin to roller friction which will increase with tension. I don't think the friction of the seals come into play for this power loss, as the seals are unaffected by the pin to roller tension. The seal friction HP losses should just be a function of speed, whereas pin to roller losses will be affected by both speed and tension, that is greater when under acceleration than when maintaining a given speed.
It seems that for high horsepower applications the sealed chain has a big advantage. On a 250 HP race bike which is accelerating hard, the friction of the x rings is nothing, the pin to roller friction will be the main power loss. In this case which is best, a chain that has had much of it's lubricant flung away by the end of the first lap and will have some road grit on these surfaces or one which has the ideal amount of the correct lube in a perfectly clean condition coating all of the internal wear surfaces of the chain?

All of which is quite theoretical for a 60 HP roadbike. For that, the coasting test is good enough to show that the x ring chain does not create any great increase in drag over a standard chain.

Glen

Senile old twat here I meant to say 1-1.5 hp not %

Going for a lie down

Yoose guys obviously have not handled a new O-ring and X-ring at same time with new plain chain as by far its the seals drag that make one chain stiffer than another - not the hardly moving pins links as such tiny distance form rotation center they contribute almost no friction to matter. Yoose guys do not seem to have studied the function of lube in chains on friction, heat and internal created grit flushing. Consider the lack of translation speed of pins in links that can not surf or form separating oil wedge but only expel oil from their interfaces. If ya ever moved dry clean polished pin/links or plain or roller element bearings before and after oil added you might get a hobot insight on the subject. If ya work a dry clean worn polished chain link vs new sealed link O-ugh or X-ah chain for sense of friction heating ya might be moved closer to hobot chain gang attitude. What wears chains is not friction of rubbing polished surfaces but the hardened surfaces micro chipping for grinding paste, unless flushed away.

Same drive train on different powered engines will cause same absolute amount of drag - power loss across same rpm ranges but will have slightly more drag in more powerful engine dt accelerating parts faster is all. Main benefit of sealed chain is 1st - lack of maintenance & mess. 2nd sealing out road grit, 3rd internal lube flushing of wear grit. Heat and friction are higher in sealed chain though not very significant in our cases. Plain chain in THIN oil bath is best of course. As we all know the quality of the metallurgy matters most.

Steve, dynos do not lie. Well maybe a little
GP teams know what gets the power to the ground best and their choice is sealed x ring. The way the sealed chain feels in your hand is not how it operates when warmed up and at speed.
The rudimentary coasting test I performed yesterday seems to say the same.

Nigel, I did ride each bike for a few miles before the test, but maybe not enough to fully warm the xring chain. If I get around to doing the test again I'll give both chains a good warmup as you suggest.
Glen

Preaching to choir-me worntorn as X-ring means Excellent to me and O=obsolete but still prefer cheaper dry plain chain changed out off a bulk chain roll when I can lift links ~1/3 out of valleys. Its very hard to find the details I reviewed on function of oil or grease in chains sealed or not and racers that change chains often don't count a withworth to road use. Keep thinking oil or grease in chains have much to do with wear or heat but industry and me know better. I got maybe 5-6000 miles out of plain chain regularly cleaned and lubed on THE Dusty Grit and 8-12,000 miles going dry - which is about same as O & X chains on my Nortons or Suzuki so nil advantage for me to run sealed chain. Chains are like tires to me - can go easy and calm with lots of chain attention for boring economy or kick up heels for lasting memories wearing stuff out fast and fun. TC's Hogslayer ran a few yards long dry plain exposed primary chains rusting to view but quite functional inside.