4605km on KMC X8 chain in Hebie Chainglider

[Andre Jute]

The KMC X8 chain, said by many to be the best derailleur chain in the world, on my Rohloff-equipped Utopia Kranich is 0.75% "stretched" at 4605 kilometres. What that means is that I can theoretically cover another 1535km with the chain, or more sensibly that I should replace the chain in the next 1535km, near enough a 1000 miles. I plan to replace it as soon as the ordered replacement arrives.

Some details for those interested. This chain has run from new in a fully enclosed and closely enveloping "oilbath" type chaincase, initially in Utopia's pricey but fragile proprietary Country chaincase, more recently in Hebie's Chainglider. It was run on its factory lube for about a 1000km, and then given a few drops of Oil of Rohloff at 500km intervals, the interval chosen as that at which the Rohloff external clickbox gets a shot of the teflon. This proved to be too much as it caused drips. When the external clickbox service interval was increased to a 1000km, the chain service was increased too. The drips stopped and visual inspection of the chain, and measurement with a dedicated tool (made by X-Tools), showed that wear did not increase noticeably. No cleaning whatsoever, and no other service or maintenance was performed on this chain. Fit and forget, except for a few drops of oil at 6-monthly intervals.

The bike runs on tarmac and most often in dry conditions but there is no evidence that either water or grit has beaten the chaincases.  The rider is hefty (95 kilos or 210 pounds), and a masher, and bike and gear weigh another 25kg or so. Frankly, I don't suppose a lighter rider who used the gears more efficiently would get as much as 10% more mileage. At these particular costs, which we'll discuss below, it is isn't worth going to the slightest effort to stretch the chain life a few hundred klicks.

Only the chain is being replaced. Rohloff's own cog shows teeth good and square still, so I'm not turning it around this time; maybe next time I fit a new chain (at 9000km cog use), maybe it will do 13,500 or three chains' worth. The Indian Amar steel chainset still has the black paint on the teeth, so I'm leaving that as well. (The Amar was fitted in Germany unseen by me as a cheap temporary substitute while I decided which crank I want. In well over two years I haven't found one that isn't ugly or, if aesthetically suited, of too low a Q factor for my bike's fat tackies and my wide stance.)

I've never had mileage this good on other chains used in chaincases. SRAM's PC-1 and Shimano's Nexus chains gave up the ghost at about half this distance on Shimano Nexus hub gearbox-equipped bikes.

I don't know how long a KMC X8 will last if not chaincased but it seems likely that it will go at least half the distance, at least in my on-road use.

The Utopia Kranich on which I ran the KMC X8 has a very long wheelbase and needs a chain with 126 links. I therefore have to buy two chains at Euro 13.90 each, discount price from my mailorder pusher, Chainreactioncycles of Belfast. However CRC gives a further discount if you buy three chains, so I ordered three chains for Euro 31.26, out of which I will make two chains, good for about 9000km between them, or about four and half years of cycling at my normal usage. We have to add a package of two missing links, Euro 4.26, and a couple of bottles of Oil of Rohloff, five Euro each, for a total of under 46 Euro. So, if we account the chain case as part of the capital cost of the bike (a doubtful proposition in the light of my experience of chaincases), direct chain cost is about half a cent per kilometer.

Throw in the cost of a Hebie Chainglider, which seems likely to last the distance of two chains, and chain costs are about a cent per kilometer. Utopia's Country, assuming it lasts two years, which mine didn't, will make the chain costs about three cents per kilometer. So the Hebie Chainglider doubles the chain cost but also doubles chain life (assumption); however, it also saves cleaning, maintenance and laundry.

I have no argument with those who think the KMC X8 is the best chain in the world; if true, it is a tremendous bargain even at the full retail price. I do know from experience that the Hebie Chainglider and the KMC X8 have given me mileage that I've never seen before.

Andre Jute
http://coolmainpress.com/andrejute.html

EDITED 17 JUNE 2011 0100 TO CHANGE 0.75mm TO 0.75%. SORRY!

[il padrone]

Just checking my KMC X8 chain (no chaincase) and it's at 12 1/16", so time to consider a new chain (Is 0.75% the same as 1/16"?). It has done 2500kms of riding so the chaincase has made a difference. The only thing that has limited my chain life is that it has had some dirt road riding, including getting dry on our Easter 4 day tour. The chain has been running with Purple Extreme lube, which is generally very long lasting and low gunk attracting. It has only been fully cleaned once, with a couple of wipe-clean and re-lubes.

I don't know whether more frequent re-lubing would have helped. The Purple Extreme is supposed to be good for 400 miles (600kms) and this is about in line with what I have done to it. The chain is now  a bit 'dirty' and looks like this, after 530kms since the last lube.




[edit] Just checking:
1. 1/16" is 0.52%, so I still have a lot of usefull life in the chain. Should go to 4000kms before it really needs the change.
2. SJS now sell the KMC X1 as a dedictaed single speed/Rohloff chain, whereas the X8, for 8 speed can be expected to be a compromise (?)

I shall mull on this for another few weeks before ordering the new chain. I actually have a SRAM PC-830 chain lying about downstairs. Opinions for Rohloff use ?

[Andre Jute]

Right at the bottom of this interesting article http://www.sheldonbrown.com/chains.html Sheldon Brown says that you should replace the chain at 1/16in "stretch" in order to preserve your sprockets. That's 0.5% wear, where you are now. Chalo Colina, a well known American bike mechanic and machinist, also recommends replacement at 0.5% wear.

We'll have to see if the new chain skips on the sprocket/chainwheel on my bike. But I think I'll pay more attention in future, use a steel rule to measure rather than the go/no go gauge that gives you a measurement for the first time at approx 3/32 or 0.75% (of presumed destructive wear at 1%), when it may already be too late.

I looked at the KMC X1 but I would need two because my bike has such a long wheelbase, and that gets a bit pricey for a component quality that isn't in fact necessary for my use. I don't go offroad, and my chain runs in a chaincase, so I'll take my chances with the X8, which has the same X strength construction feature. I'm happy with the X8, despite everyone else getting better mileages than I do; after all, the X8 has given me double the mileage I reached before.

Andre Jute
Off for a ride!