On Thu, 20 Feb 2003 03:23:58 GMT,
[email protected] wrote:
>John Everett writes:
>
>> If a chain is kept clean and well lubricated it will last a very long time indeed. I've gotten
>> over 18,500 miles from a Dura Ace chain, and when it broke (see my posting on the "HG Chain
>> Compatibility Question" thread) it still wasn't worn out. The point is, at 2000 miles the chain
>> in question may indeed be in good enough condition to run with a new cassette and rings.
>
>I'm curious. Are you sure you didn't mean 1850 miles? What was the wear at that time? I have seen
>chains that were 1/4" off per foot and looked perfect on the ruler when looking only at the
>endpoints, the place where the chain was again in synch with 1/4 inch marks.
>
>How long did it take to put on these miles and where do you ride where there is so little dust, let
>alone rain and grit that, you got essentially no wear?
>
>> The only way to know for sure is to measure it, but considering the cost of the new equipment vs.
>> a new chain I'd be tempted to replace it if measurement shows any wear at all.
>
>Something doesn't add up here.
Jobst, if you rode with me you'd find it adds up perfectly. The chain in question came new on my
Vitus 992, purchased in 1992. That was, and remains, my "good bike". I live in Illinois (flatlands),
and never, never, never ride that bike in the rain.
I'm also a bit anal about cleanliness, particularly on that bike. As I've posted previously, I
regularly remove, thoroughly clean (scrub with Simple Green and a stiff toothbrush) and hot wax my
chains. At the same time I generally remove the rings and cogs (that bike came with loose cogs, not
a riveted cassette) and clean them individually.
I know how to measure a chain for wear.
I always measure over two feet (instead of one), and as
I seem to recall (that chain let go in 1995 or 1996) it measured slightly over 1/16" of wear (over
two feet) when it let go.
I replaced that chain with another Dura Ace and rode for another few years (again, avoiding rain or
winter riding) but lost track of mileage. It was easy to track the first chain's mileage because the
bike, chain, and cyclocomputer's odo all started at zero.
A couple of years ago I upgraded the Vitus to 9-speed (Dura Ace), and used the extra bits to upgrade
my beater (Trek 1400) from 7-speed to 8-speed. The ORIGINAL 8-speed cassette is still in use on the
Trek, at least in one form or another. Since the cogs are loose I regularly mix and match, but some
of the original cogs are still on the Trek. I believe the Vitus came with 12-21, but on the Trek
it's currently 12-27 (or so); which is left over from a Rocky Mountain trip last summer. I'm sure I
could reconstitute the original cluster if I wanted to. My conservative estimate is that the
original cluster (at least most of the cogs) have seen well over 40,000 miles, as have the rings
which are still on the Vitus.
As a former engineer with Porsche (correct, Jobst?) you're no doubt aware that chains drove the cams
on the original 911 engine (and lots of other engines for that matter). In a clean and well
lubricated environment a chain will last a very long time indeed. Why would you expect it to be any
different on a bike?
BTW, as I sit here I'm having a hard time remembering if the 911 had two chains or just one long
one. I last rebuilt one (for an SCCA C-Production race car) in 1972. Was it two chains or one? In
any case it was the longest chain run I've ever seen on an engine.
jeverett3<AT>earthlink<DOT>net
http://home.earthlink.net/~jeverett3
