GPVB1@cs.com wrote: I seriously doubt that one would see huge differences (the 1% vs. 2% argument), and that the Campy crankarms failed more in part because they made way more of 'em, and on average, they got used for longer periods of time / more pedal revolutions / by more "serious" riders.
I certainly agree with you said here... except going form 1% to 2% failures is a 100% increase in failure rate. But you know that,and this isn't what you really meant, so I'll shut up now.
Tom amused by really small and really large numbers Dalton
GPVB1@cs.com wrote:Tom:
Thanks for your detailed, thoughtful post. I agree with everything that you agree with me on! ;-)
Thanks Dale for giving us a place to engage in "spirited discussion" about something we are so passionate about....
I don't agree that a few years is enough to assess long-term crank arm durability tho'... Let's see what the data show in twenty-five. The majority of cranks that break do so well past their intended design life from what I've seen.
I'll add that the only points that I was attempting to make were the following: if one could accurately quantify the *rate* of failure of the Campy Record crankarm and it's various contemporaries, I seriously doubt that one would see huge differences (the 1% vs. 2% argument), and that the Campy crankarms failed more in part because they made way more of 'em, and on average, they got used for longer periods of time / more pedal revolutions / by more "serious" riders.
Let's reconvene in 40 years and check our anecdotal evidence!
Cheers,
Greg "still crankin' " Parker A2 MI USA
P.S. What do you mean "*some* of my ideas are interesting?" :-)
Tom Dalton wrote:
> Date: Fri, 30 Aug 2002 10:47:42 -0700 (PDT)
> From: Tom Dalton
> Subject: Re: [CR] New Equipment Failure Rate
> To: classicrendezvous@bikelist.org
>
>
> Oh, no. Iâve done it again. An overly long, overly detailed reply to one
> of Gregâs posts. Greg, this is not intended as an attack. Some of your
> ideas are interesting, and inspire me to think about stuff⦠and write.
>
> Tom D. wrote: Bob, 9-speed Ace has been around since 96 IIRC, and the new
> Record group rolled out in 1995, though there have been annual changes, as
> is now
> standard for Campy. Six or seven years is a long time. Under an
> elite/pro rider, a season or two is all that can be expected of this stuff,
> as
> was the case with NR/SR stuff.
>
>
> Greg wrote: Six or seven years is definitely *not* a long time in terms of
> major
> bicycle component durability IMHO!
>
> I think that you missed my point. My point was that the 6 or 7 years that
> the current top-end groups, each of which featured a new crankset
> incidentally, is sufficient time to demonstrate that these groups are at
> least comparably reliable to what came before. It has been enough time to
> confirm that these are solid groups with sufficient reliability to meet the
> demands of athletic competition and the demands of the marketplace, and
> that these groups are not delicate relative to the older stuff, as Bob had
> suggested. Six or seven years was enough time for Shimano to decide that
> the sharp edges of the 7700 crankarm were a problem and that easing the
> edges and rolling out the 7701 was warranted. So I maintain that from a
> âfield verificationâ standpoint, 6-7 years is a long time.
>
> It seems that the point you are making is that 6-7 years, under the
> referenced conditions (elite/pro use), is not a long time relative to the
> total expected life of major components if the lifespan is defined by the
> point of failure. This may be, but use to failure is not consistent with
> typical use, in my experience, and I will go so far as to say that failure
> is not reasonable determinant of the lifespan of parts for which failure is
> not a safe option. But mileage, stress cycles, and so forth aside,
> consider the general visual condition of a crankset that has been used
> daily for six years. Thatâs a crank with lots of lost anodizing, nicks,
> and dents on perhaps its sixth set of ârings. Even if it isnât cracked,
> is it something you want on your bike? Is it something that any
> performance-mined rider would want to use?
>
> Greg wrote: 20 - 40,000 miles (based on your 1-2 year
> figure) under a pro-level rider should do less damage to a set of cranks
> than
> the same amount of miles from an equivalently-powerful amateur (the pro
> should have a more consistent and smooth cadence and power delivery - less
> load
> fluctuation).
>
> I think the distinction you draw regarding pedaling style may be a bit of a
> reach. Like I suggested earlier, I think things other than number and
> magnitude of cycles are at play where real-world durability is concerned.
> However, Iâm reluctant to accept that one such difference is some
> fundamental difference variation in pedaling style between proâs and
> elites. Iâll speculate that if one bothered to quantify load fluctuation,
> pro and elite riders would be near the top of the distribution when the
> population is all cyclists, but if you were to look at just pros/and
> elites, I doubt you would find some sort of bimodal distribution. I think
> that beyond a certain relatively low experience level, riders have their
> pedaling style pretty much set, and that the differences among individuals
> are far greater than the differences between the means for pro and elite
> groups.
>
> Greg wrote: The Campy Record cranks that many say are so crappy have been
> around since 1958 - that's forty-four years, or nearly seven times as
> long.... The
> vast majority of 'em still ain't broken yet!
>
> I, for one, never said they were crappy. I love those cranks. They are
> beautiful, the Platonic Form of a crankset. A gorgeous piece of alloy
> where all that isnât a crankset is cut away (except that little web ;-).
> To me, they are the essence of a crankset, but thatâs certainly due to
> historical circumstance. In any case, they were always the default
> standard, were widely available, and they worked. How well? Well enough.
> In general, by the time they broke, they were pretty beat up. Naturally
> there were exceptions. Of course, if the vast majority still arenât
> broken, it may reflect that fact that the vast majority are no longer
> ridden and many have been tossed for reasons other than breakage.
>
> Greg wrote: What's the predicted useful life of the glue in carbon-fiber
> cranks if
> they're exposed to Southern California levels of Ulraviolet light exposure
> eight hours a day? Five years? Ten?
>
> Even five years sounds like a long time, but I have no idea. Those are
> $800 cranks that will be yesterdayâs news relatively soon, whether or not
> they are still intact.
>
> Greg wrote: As far as the machined aluminum cranks that are out there on
> the market are concerned - intuitively, a crank arm CNC'ed from raw
> aluminum will
> likely not be as strong or durable as an equivalent-section forged aluminum
> one -
> think about it for a moment. Do racing engine manufacturers use CNC'ed
> crankshafts? No - they are forged. Same goes for the crankshafts of
> 18,000 horsepower diesel ship engines.
>
> I hear you there, no need for comparisons. Forged-to-shape is obviously
> preferable. (As an aside, the local BMW dealer told us that, displacement
> aside, the 328 was âbetterâ than the 323, but couldnât give any specific
> examples. My girlfriend went on-line at work and came home telling me she
> wanted a forged crankshaft, not cast. Then she asked what the difference
> was.)
>
> Greg wrote: Again, I think folks have a ton of 20/20 hindsight regarding
> vintage
> bicycle part design. We all enjoy being armchair quarterbacks, but you
> can't re-design something in the 1970s while sitting in the 21st Century
> (well, at least not
> without a time machine...).
>
> Yep. I hoard stuff because it was special in its day. Maybe Specialized
> cranks were better in 1983, but they sure werenât what I was lusting after
> while pouring over the Nashbar catalog in math class.
>
> The new bikes are often worn as a fashion statement, and changed
> frequently, along with the jersey, shorts, helmet, accessories, SUV, etc.
> This is
> because many of the "new age" roadies come from a motorcycle/MTB background,
> where spending big bucks often to "upgrade" your ride/equipment is
> considered
> part of the game.
>
> I agree about the MTB thing, and Iâd add that tri-guys have contributed to
> this attitude. I think there are larger trends at play too. There is
> bigger money in road cycling now, bigger budgets for the team, more money
> from TV, more money spent by sponsors. But over and above all that, I
> think there is something different in the demographics of âseriousâ
> cyclists in the US. They are getting older, so they have more money. Of
> course, the young ones are gen-Y extreme sports types for whom owning the
> âgearâ is the same as actually doing the sport. I dunno what it really
> is, but I keep thinking about it. My girlfriend tells be that the
> generalization accepted by marketing people is that Boomers are more
> âexperience focusedâ than younger consumers. They would rather pay to go
> on a vacation than buy a new car. So, maybe itâs the younger riders who
> are supporting the equipment mania.
>
> Nothing inherently wrong with that; the Marketing folks
> have a field day with it, but it is certainly unnecessary, and encourages
> the
> spread of our growing "throw-away" society (e.g. frames / components that
> only
> need to "last one or two years").
>
> Iâll accept the ill effects of our throw away society as they apply to
> bikes. If it keeps people riding for fun rather than ATVâing through
> old-growth forests, if it keeps people excited about riding to work, if it
> helps make a small part of the population healthier, than Iâll accept some
> energy and environmental costs for recycling, manufacture, etc. I know I
> shouldnât look at bikes in isolation, and that the whole throw-away
> attitude is problematic, but I think the really scary part is the way we
> throw away clean soil/air/water, non-renewable fuel, open space, etc. to
> support a car-based society. Then again, itâs my job to help oil companies
> comply with environmental regs⦠at the least possible cash outlay. Who am
> I to talk?
> Tom Dalton
> Bethlehem, PA
>
>
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