Conference noted::bicycle

    My PX-10 is 14 years old now.  With about 12 years of fairly regular
    riding.  The frame (and fork) is Reynolds 531 db.
    
    does that help?
    Barry

    You'll know your frame is worn when you're picking yourself up off
    the road  :-)....
    
    
        Regards,
    
                  Chip

re         <<< Note 1797.0 by ULTRA::WITTENBERG "Uphill, Into the Wind" >>>
>                            -< Do frames wear out? >-

>    How long  does a bike frame last? Do frames "wear out'? If so, how
>    long does it take and how can you tell that the frame is gone?

>    I'm mainly  interested  in  steel  frames, but discussion of other
>    materials might interest others.

	I have a 531 frame that is  .....errr, older than you are 
{betcha} and in at least as good condition {betcha again}  (-:, (-:
This isn't a clunker either, about as light as any present day steel 
frame is likely to be.  I've done double centuries and the Pan Mass on
it in recent years. 

	Unless you store them in cold damp places and get  *_A LOT_*  
of condensation inside the tubes and/or crash them, leave scratches to 
rust, etc., a good steel frame should outlast you. (I think mine is 
going to outlast me.)

	"Gone" ?   Try the usual flex tests, if it creaks and moans it 
probably has a crack or a brazed joint that is opening up.

	R

    
    The replies so far have answered "how long will it last?" in
    terms of "how many years?" - rather than "how many miles?"
    
    Somewhere in this Notes conference, I recall, the following
    figures were given:
    
      steel   - 100,000 miles
      aluminum - 50,000 miles
      carbon   - 25,000 miles? (still new, emerging technology)
      
    Titanium wasn't rated, but probably exceeds steel by a long shot.
    These figures represent ageing due to fatigue (not rust or other
    corrosion damage, or crashes), and is the mileage after which it
    might be best not to trust the frame.  It assumes moderately
    strenuous use, but not the pounding of a Tour de France.
    
    For some people, the above figures influence which kind of frame
    to purchase.  For me it has.
    
    Some where after 100,000 on my Fiorelli frame, the downtube started
    to crack, whether from endemic corrosion or what (it had not seen
    much rain, and had always been kept indoors - at work, at home).
    So I retired the bike.
    
    Some people (some racers) feel a frame goes out of tune long before
    that, and this was interpreted in a Bicycling article in the last
    years as the frame's needing alignment - which some shops or frame-
    builders will now perform.
    
    -john

RE> Steel - 100,000 miles

I remember reading in a bike rag the same facts only the measurement was in
cycles not miles. The tests weren't on a frame but on the frame material and 
the facts were...

steel - loses stiffness in the first X number of cycles and then reaches a 
	level of stiffness and it sort of levels off to a long slope of 
	declining strength.

Aluminum - loses stiffness/strength in a constant manner.

T
  

                       

    Titanium is advertised as having 4 x's the tensil strength of steel
    and 2 x's the fatigue. These characteristics, coupled with the
    fact that it is corrosion-proof should provide a long life.
    
    I hope so, I just bought one and they ain't cheap!
    
      Chip

> steel - loses stiffness in the first X number of cycles and then reaches a 
>	level of stiffness and it sort of levels off to a long slope of 
>	declining strength.
>
> Aluminum - loses stiffness/strength in a constant manner.

It it true that Aluminum will continue to lose strength, but it takes a
while before the curves diverge.  If one cycle is taken to be one
pedal stroke, then in a fifty inch gear, you get 400 cycles per mile.

I'm not a metalurgist.... but I play one in notesfiles.


The graphs that I saw showed steel leveling off after 10^6 cycles.
(roughly 3k miles).  From then on, it it suffered very little more fatigue.

Aluminum loss of strength was a straight line when plotted on a log-log
scale.  (The same as steel before steel leveled off.)  This means that the
the amount of strength lost between 10k miles and 100k miles is the same
percentage as lost between 100 and 1000.

Can anyone feel the difference between a bike that's been ridden 100 miles
and a bike that's been ridden 1000?  (It's not a rhetorical question.
Maybe some people can... I don't know.)
---------------------


What about other measures:  (I'm guessing at numbers)

    Mean time to damaging crash (depends on rider):
        Al   10,000 mi
        Fe   10,000 mi
        Ti   30,000 mi

    Mean time to Ireperable crash
        Al   10,000 mi  (no fixes)
        Fe   30,000 mi  (cold setable, brazable)

    Mean time to corrosion death
        Al   100 yr
        Fe   30  yr
        Ti   1000 yr

    Mean time to strip BB threads
        Al   50 overhauls
        Fe   300 overhauls

    Mean time to failure of knees
        Al   80 years
        Fe   80 years
        Ti   80 years


-Jeff Bell

    
    
      I can feel a definite difference in my steel(crmo) specialized Allez
    the first year I rode this bike it was much more resilient in its
    reaction to both steering and road stimulus.  the feel of the bike has
    become more "dead" now than it used t be.  I consider this bike to be 
    at the "Autumn" of its racing days. There is some rust inside the tubes
    and there are some creaks beginning to voice their nasty opinions.
    
      I am also hoping to save up enough money to get a Titanium frame for
    the summer of '92'.  I figure that will be the last fram I buy for a
    VERY long while.
    
    John C.
    

    resurrect an old note...
    I have an '88 Trek 1200 with about 25,000 miles, or about half
    that of which .4 indicated it should last.  There are no stress
    fractures in the frame, and I've gone over it pretty thoroughly
    [at least the paint isn't cracked anywhere].  I weigh about 200
    pounds and make frequent trips up the local mountain, so it sees
    some serious torque.  Anyhow, when I stand next to the bike, holding
    it firmly, and put all my weight on a pedal, the frame moves a good
    part of an inch, if not more.  In other words, pushing down on one
    pedal dramatically moves the lower part of the frame (BB) to the
    other side.
    
    Just curious: does anybody else have a semi-hi-mileage aluminum
    (this is Alcoa 6061t6; probably not the best) frame that has
    begun to turn to jello?  Thanks in advance, Kratz

>                 Anyhow, when I stand next to the bike, holding
>    it firmly, and put all my weight on a pedal, the frame moves a good
>    part of an inch, if not more. 

So, you weigh 200lb, and you put all your weight on one pedal while 
holding the bike firmly, and the bottom bracket moves a good part of an 
inch? You should try that with my bike sometime and then you won't feel
so bad.

Are you happy with the way the bike rides?


Rod

     Or mine! I go about 165lbs and can swish the BB around (but that's
     due to the immortal powers I possess... Ya).
    
     Aluminum has very unforgiving movement. It won't soften, it'll
     crack. It certainly won't get "mushy" without  tell tale (visible)
     signs of fatigue. Is it possible you had just never noticed it
     before?
    
     Ohhh, are looking for an excuse to buy a new frame???? :-)
    
     

    re .last few
    Thanks for replying.  The bike now creaks pretty badly under lots
    of torque [embarrassingly so], and I don't remember it ever being
    as "mushy".  But I've had a cracked frame on another bike, and that
    was pretty obvious.  Maybe I am just trying to justify a new Ti frame.
    Alas, Mr. tax man ensured that won't be happening anytime soon.  ;-(
    Thanks again, Kratz
      

     I owned and raced a C Dale that creaked. It wasn't the frame at all.
     The funny thing about it was it sounded like it was coming from all
     areas of the frame that it (actually) wasn't. 
    
     The seat post/seat tube was the culprit. Even my Merlin was creaking
     to beat the band after the monsoon race in Marblehead. I just pulled
     the stem, wiped off the crap and re-greased it... Silent!
    
     Sorry to hear about Uncle Sam bein' so tight (not like him, eh? - Ya
     right!)...
    
     Maybe next year...

    I recently bought a "used" Trek 1200 from Ron Pleva in Jersey
    and thought I'd revisit my note in .9.  Ron's 1200 is
    essentially a carbon copy (aluminum copy?) of my other 1200:
    same size, same aluminum frame, same color,... the main
    difference my old 1200 has about 20,000 miles more than Ron's.
    Anyhow, keeping everything else equal (same wheels, etc) the
    difference in terms of riding is *absolutely* amazing: Ron's
    1200 responds instantly and is at least 1mph faster; my old
    1200's frame moans and groans as it squishes under torque.
    No visible signs of unbonding or cracks either.
    
    Perhaps this degradation is peculiar to aluminum, or maybe the
    particular aluminum alloy used in this frame, but frames can indeed
    "wear out".
    Kratz
    

         Steel is unique because if stressed to less than 50% of its limit,
    it has an infinite endurance limit.  Aluminum, like other metals,
    fatigue.  The rate is a function of the stress load vs. the limit load.
    I was surprised(?) to learn that a standard maintenance procedure for
    airplanes is to measure the length of the cracks in the aluminum skin.
    When they reach a specified length, the panel is replaced (we hope)!
    
         Endurance limit is defined by number of cycles and stress level. 
    For a bicycle, load/unload cycle would include pedaling and just
    bouncing over bumps.  20K miles could rack up a lot more cycles.
    Without getting too technical, fatigue can show up as "softening", not
    just cracks.
    
    Regards,
    Tom