From: warkenti@CAE.Mitel.Com (BJ Warkentin)
Newsgroups: rec.motorcycles,rec.autos
Subject: Re: Durability
Date: 17 Dec 92 16:24:59 GMT
Organization: MITEL, Kanata, Ontario, Canada
In-reply-to: johnsw@wsuvm1.csc.wsu.edu's message of 13 Dec 92 19:40:50 GMT

Bill E. Johns writes:

   Why are bikes and cars so incredibly fragile?                                   

   I mean, we would like to think that if we could get our bike or car, any        
   bike or any car, to say, 100,000 miles, without major problems we are           
   having a near mystical experience in reliability.  Bullshit.  At an             
   average of 50 mph, 100,000 miles is only 2000 hours of operation.               
   That's nothing compared to the reliability of many mechanical systems.          

Many, many, many mechanical bits and pieces and a very shitty
environment coupled with lousy maintenance. Background some which I
speak is being a reliability engineer (telecomunications) but have had
some dealing with mechanical systems and backup disel generators.

Consider planes: Much better engine design due to legal liability and
consequences of failure and required tear downs at X hours (1000
around here). 

The two key issues are maintenance and environment. 

Maintenance: - oil changes
             - keeping things in tolerances
             - keeping things clean to prevent corrosion
             - realizing that things mechanical are essentially
               consummables (ie belts, rings, bearings, gears, etc)
               and replacing as required
             
Environment - high levels of vibration and corrosion
            - large and rapid changes in temperature
            - lots of localized heating and stress due to temp
              gradients ( bigger problem on a bike with electronics
              so close to engine )
            
Couple this with design engineers would are not trying to design
things to last forever, just the right length of time. Design is
pretty much to the minimum of what people will accept. This shows in
the selection of connectors, engine materials, plastics, etc and in
the amount by which things are over engineered. Compare BMW's cylinder
wall design process to that of Honda. They are playing to different
markets. People want reliability but they don't want scheduled
maintenance and don't want to have to pay extra for the higher
material and manufacturing cost associated with it.

   So what is it with bikes and cars that makes them so fragile.                   

Basic design! Even with religious maintenance you will still be
looking at end of life failure due to simple mechanical wear due
mainly to material selection/cost optimization. The problem is that if
you do not have the tools/knowledge to fix things yourself the shop
charges vs current value will result in scapping and replacing a bike
or car once end of life things start happening. 

Case in point: I have an Escort with 200,000 kms and it needs inner
and outer tie rods, new struts and springs, and other assorted bits.
Even material cost is more than the car is worth. If I considered shop
charges it is probably several times what the car is worth.  

BJ...warkenti@CAE.Mitel.Com    |   XJ650K and DoD#0255
Kanata, Ontario, Canada        |   I want a new toy...
I really didn't mean it quite that way, or did I :->
Newsgroups: rec.motorcycles,rec.motorcycles.harley