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Old 06-04-2008, 10:21 PM   #1
WzlTech OP
The fool on the hill
 
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Joined: Feb 2006
Location: Stuck between reality and insanity.
Oddometer: 479
Chain Dissection: The O-Ring Advantage

Well....I guess this is mostly just an FYI for y'all cuz I thought some folks might find it interesting.

I pulled the OEM chain off the dirty ol' 6-fitty. It had a number of o-rings missing, some from rather early in it's life (<5000 miles), and has lived with almost no cleaning, but frequent liberal doses of assorted lubes (not WD-40) in the last 7500 miles or so. Let's just say the chain was fairly abused later in life, but lubed, and suffered from a lack of lubing in it's early life (which no doubt led to the initial o-ring loss).

Anyway, the OEM chain was an EK520SRO, and though technically it was still within spec (12.7" for 21 pin span) I had a feeling most of the wear would be in the pins missing o-rings. Further, having most of the wear (~12.6") spread over a relatively few pins didn't strike me as a good situation.

Mileage: 16,270.8 miles

Inner pins (ends stick out through the outer sideplates)


Outer pins (stick out through the inner side plates, rollers ride on them)

(you can note some wear from the roller on the left pin; the rollers, not pictured here are what actually contact the sprockets; the actual rollers appeared to have minimal wear on them)


(this was the most startling wear in my opinion; caused by the inner pin and a lack of lubricant because of a lost o-ring...with o-rings intact there is no appreciable wear in this area since the original grease was sealed in; I did check an intact link)

Front OEM sprocket 15-tooth...not bad wear, but a fair amount


Rear OEM sprocket, 43-tooth...wearing well, but one tooth tip 1/4-1/3 chipped off (not shown)


What's it all mean?

If the o-rings are intact, and schmutz hasn't worked in past them, or the grease out somehow, the inner pins should have very minimal wear because of their sealed design. The greatest wear will occur (assuming the same caveats just mentioned, o-rings intact, etc.) on what I've called the outer pins; on the outer surface that the rollers are mounted around.

This makes sense particularly when considering the outer pins fixed position, lack of "permanent lubrication", and the relative difficulty in getting lube in (and dirt out) between the rollers and outer pins. The very fact that the rollers have the ability to fully rotate around the outer pins gives them the advantage of exposing all their surfaces to wear. Whereas the outer pins are going to have the majority of wear and stress applied to the same sprocket side surfaces throughout their lifespans.

One last thing, the rollers were actually composed of thicker material than the outer pins. I measured them at the time though I don't have the numbers now. There were a few spots, where I could measure, that get no or very minimal wear so it wasn't just a matter of wear that accounted for the difference in material thickness.

Guess that's it, I'll now open the floor for questions, comments, trolls, and pot-stirrers.

WzlTech screwed with this post 06-04-2008 at 10:30 PM
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Old 06-05-2008, 12:54 AM   #2
ibafran
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Joined: Apr 2007
Location: chicagoland
Oddometer: 1,240
I found your deconstruction very interesting.

Obviously, each wearing surface contributes to the total wear figure.

Where do you think the most wear occurs? Chains or sprockets?

If we could eliminate wear to even one component, we might gain a considerable cost savings.

Currently a manufacturer ( www.sidewindersprockets.com ) is offereing a lifetime replacement if the sprocket ever wears out. The wheel sprocket costs about $160US Wouldnt it be nice if a new chain fit well on a sprocket that had 100k miles on it? Buying the big expensive sprocket at the first chain swap and never having to replace it would mean a complete payback at the time of the third chain replacement.

Its been my experience that my chain&sprockets need replacing at about 25k miles. A new chain will not lay over the old chain wheel so the sprockets are replaced with the chain. Sprockets are steel.

When I do this, I move the wheel to the forward limit and cut the chain as short as possible. Thus, I have the most room for chain wear/stretch possible. The bike (95 Trident) has eccentric adjusters and the original fit of chain length allows for proper adjustment. An Oiler supplying 120wt gear oil keeps the chain damp and fairly clean. Occasionally, various spray chain lube may be used as an addition to the gear oil during LD rides.

At about 15k miles, the adjusters come to the rear stops. At this point, the adjusters are moved forward again and 2 links were removed to restart the process. An additional 10k miles can be gotten from the chain before everything is so worn that the chain will not lay on the sprocket very well.

I have never been able to determine what is wearing the fastest. I suspect that the interior surface of the roller is the weak spot. O-rings do not seal it. Dirt may work its way in there with chain lube carrier solvents. Your pics make the interior of the roller look elliptical to me.

Turning the sprocket around at 15k didnt seem to help. Nor did turning the chain over so that it would bend the other way. (Hey. I was just trying to eliminate some obvious possibilities.)

Is there something that I should know? Do I need to be concerned that a specific sprocket manufacturer works best with a specific chain manufacturer? I have always ass-sooomed that all 630 chains mate well with all 630 sprockets.

The price of non-o-ring chain in bulk looks like a good deal if the sprockets wouldnt wear so badly. A rider could put cheaper, but new, chain on the bike every 15k if the sprockets would hold up.

Sorry for the all-over-the-place post. Its late and I cant seem to pull it together at the moment. Your thoughts on any of this would be appreciated.

Its bad enough having to replace tires, oil, brake pads without chains&sprockets too.
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ibafran screwed with this post 06-05-2008 at 01:03 AM
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Old 06-20-2008, 03:58 PM   #3
mitchsma
posting from Patagonia
 
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Joined: Jun 2008
Location: San Martin de los Andes, Neuquen, Argentina
Oddometer: 24
Well, my experience with chains, first on MX bikes, then on street bikes, is that the better the chain care and lubing, the longest the life on sprockets.
My usual wear ratio on MX was:
wear 2 chains
when replacing the second chain also replacing front sprocket
wear 2 chains, then replace both sprockets.
That was on MX and following manufacturer wear specification.
Then with the Transalp 650, followed the same pattern.
Usually a chain lasted 20-25k km, after the second chain also changed the front sprocket. sold the bike with 50k kms and the rear sprocket was like new. Used Scottoiler since odometer showing 13000km. Always keep it lubed. After some experience, I decided to change the chain no matter wear every 20000km, as on a long trip, with the chain with 22000km and perfect condition, suddendly collapsed, links got jammed and all that in the middle of nowere. Lesson learned, change chain at 20k even if is on good shape. At least that was my experience, now I own a shaft bike, so those problems are gone.
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