O-Ring
vs. Non-O-Ring chains
After the WD40 experiment was over, it was time for another experiment. The factory chain (an EK520SRO o-ring chain) is established as the longest-life chain in our KLR universe but it’s pricey at well over $100. The factory rear sprocket shares the same “best in class” reputation with significant life, and is priced in the mid $40 range.
So here I was with a little over 34,000 miles on the rear sprocket, and it still looked pretty good but if I was going to spend $100+ on a new factory chain, then I clearly should have purchased a new rear sprocket as well. But since my rear sprocket was still in pretty good shape, it seemed like a good time to continue using it with a cheap, non-o-ring chain and see if there was any MPG improvement in the reduced drag of no o-rings. Heck, it would be cheap to find out at this stage, and I could continue to go to 40,000 or even 50,000 miles on the stock rear sprocket.
I purchased an EK520 standard chain for a mere $28 and put it on. But of course, I now was forced to use commercial chain lube, as WD40 was a path to short life on a non-o-ring chain. I’ll state the bottom line right up front, with details after that:
1) Fuel economy
only went up by 1 MPG. (To be
fair, this was comparing a worn
o-ring chain to a new non-o-ring chain.
It is possible that a new
o-ring chain has more drag than a worn one, so we will see in the future if I
lose more than that 1 mpg when going
back to a new factory o-ring chain.)
2) You get what
you pay for – the $28 chain is wearing (“stretching”) 7 to 8 times as fast as
the stock chain did!
3) WD40 created no mess at all. Using standard chain lube now, the bike is a greasy pig that drips under the countershaft cover, has a messy swingarm, rim and rear tire.
OK, here are the details.
Fuel Economy:
There are a lot of misleading fuel economy posts on the ‘net. Not filling the tank to the same level is one issue, partial fills are another (posts where someone rides 80 miles and then buys fuel, rather than running the tank empty) are not uncommon. Throw changes in riding conditions into the mix and ‘data’ can be all over the place. For that reason, I tend to run multiple full tanks and average them all together before quoting what kind of fuel mileage a vehicle is getting.
Fortunately, my commuting cycle is very consistent and thus, economy varies very little from tank-to-tank. When commuting, I’ll typically get to around 320 miles before switching to reserve, then run another 40 plus miles before buying fuel. So these tanks average out at over 360 miles each… these are not partial fills.
Look at the figure below. The last ten commuting tanks with the original o-ring chain are shown in magenta and average 67 mpg. They are all in a tight band, all between 66 and 68 mpg. The first six commuting tanks with the new non-o-ring chain are shown in blue and average 68 mpg. They are all in a tight band between 67 and 69 mpg. A very small difference, but as you can see by the data, I have very little tank-to-tank fuel economy variation so the 1 mpg difference does seem to be clear. But still, 1 mpg. This is clearly not a reason to switch over.
To not clutter the issue, the results for two fifteen-hundred-mile road trips over this interval are covered in the figure and not included in any math as the riding cycles are different (some dirt riding, or higher speed road work) and should not be compared. So this is why it took so long to post results… this covers nearly 10,000 miles of riding.
Chain Wear:
The same procedure outlined in The WD40 Experiment was used to monitor chain wear. The cheap non-o-ring chain required adjustments far more frequently! The blue line below shows the chain wear with mileage so far. For convenience, I’ve shown a magenta line as well which is the stock o-ring chain data from new, as if it was installed at the same moment. In just over 4,000 miles, the EK520 has stretched just under 1 percent. It took 30,000 miles for the stock chain to stretch that much! The cheap chain is wearing 7 to 8 times as fast as the original… wow.
So – I’m getting a free ride on this rear sprocket, but buying seven or eight 28-dollar chains is clearly more expensive than one EK520SRO!
For the record, I used Maxxis “Chain Wax” for the first 1,500 miles, and Maxxis synthetic “Chain Guard” for the remainder. I don’t see a difference in slope of chain wear.
Some will argue that the rear sprocket was already “worn to 1%” by the original chain when the cheap chain was installed, so the cheap chain wears faster. If that is true, then the blue line should start flattening out in the next tests, as I’m into a wear regime that the rear sprocket has not seen yet. Time will tell. Let’s give it another 5,000 miles and see what happens.
Mess:
Wow. I’ve been riding chain-driven bikes for over 40 years, and had forgotten how messy it used to be before the switch to WD40. The stocker o-ring chain with WD40 was so clean… the rear rim was clean, the rear tire was clean, the swingarm too. You get used to it. There was never a drip under the bike.
And then I went back to normal chain lube.
At first, it didn’t seem like a much bigger mess. That’s because the lube is flinging off inside the countershaft sprocket cover, and it takes a while to get enough in there that it starts dripping out the bottom. Every day or two, a drop of grease under the bike. Then I roll the front tire through it, or step in it - either way it gets spread around the garage floor. Now I put a pan under the bike each night. Wow, I do remember this from the 70’s, 80’s and 90’s…
Costs:
Looks like WD will win this one… clearly it is cheaper to buy one good chain instead of multiple cheap chains. And then there’s the cost of the WD40 (usually around $3 a can) vs. chain lube that is 2 to 3 times that much.
Bottom Line:
It has been interesting.
I’ll keep going as it’s free to continue wearing out this chain and rear
sprocket to see if things change from what’s reported, but when this chain and
sprocket are worn out, I’ll buy the original EK520SRO chain and a new rear
sprocket from