From: praetzel@marconi.uwaterloo.ca (Eric Praetzel)
Subject: Re: Re: Tioga or Sugino Disk Wheel  /  "harsh" radial spoking
Organization: University of Waterloo
Date: Thu, 15 Oct 1992 16:44:00 GMT

In article <102520007@hpfcso.FC.HP.COM> khe@hpfcso.FC.HP.COM (Keith Erskine) writes:
>In rec.bicycles.marketplace, praetzel@marconi.uwaterloo.ca (Eric Praetzel) writes:
>  I write "How the @#%% can they think that there is any diff. between a
     disk and spoked wheel"

>Every mountain biker I have met who use the Tioga tensioned string disk
>wheel says it absorbs a noticable amount of shock.  You are assuming
>that all of the flex is in the rim as opposed to in the "disk".
  No.  I am assuming that they are human and that what they experience is
a mixture of sound, sight and smell and that there is almost no chance that
they could detect and deflection of the tire.  99% of people can not tell the
difference between a $7 and $100 tire and tires have > 10* more flex than
the rim.  Every study has come down against people being able to tell how
"harsh" or how "controled" a ride is (car data).  I doubt that people can
detect frame flex (aside from noticing it in chain rub) but they most
certainly feel the result of shock absorption by the tires and flex in
the fork steerer tube.  However, they experience a whole lot more and
there is almost no way for them to detect what part is due to the tire
/rim/forks/frame/bars/human tissue/muscle and what is sheer overflow from
another sense.  Rim flex is simple enough to measure and test and simulate
and there just is not enough flex there to account for any significant shock
absorption compared to the tire/fork.

>If it makes you feel superior to scoff at the experience of other cyclists,
>go ahead - it in no way makes your viewpoint any more correct than
>the cyclists who find the Tioga disk does help absorb shock.  
  Of course it makes me feel good.  All people live within their own delusions
and some are harmfull while most are not. However, I would not rush out to buy
Tioga disk wheels for "shock absorbing" qualities.  You would be better off
getting larger tires and using less pressure.  If you want to have some
fun lace a wheel with shoe-string (thats the only way to allow the rim to 
"flex") and go for a spin.  Tell me how strong the wheel is.  When you lace
it up with spokes or strong wires (acting in tension) you will have a much
stiffer structure that can take lateral loads.  When the lateral load becomes
so large that the spokes loose tension you will potatoe chip the wheel.  The
only way to make a "soft" wheel is to loosen the tension and at that point
it will have no strength at all.  If you do manage to keep all force in the
axis of the rim/axle you will destroy it with fatigue in no time regardless.
  Rim flex and frame flex should be kept in the same breath that you use to
talk about astrology and tarrot cards.  If you still think its significat
take the tires off your wheel and measure the hight (ie concrete floor) to
the top of the rim.  Climb on your bike and get someone to measure it again.
Do it a few times to make sure your readings are consistant.  Then try it
with a tire.  Measure the wheelbase (axle to axle) and you will have to
come to the conclusion that flex is in the tire not the frame or wheel.
As an additional experiment put a pen on the ground and ride over it.  Measure
the additional "rim  flex" and compare that to additional tire flex.  Then
throw any idead of rim and frame flex into the toilet where they belong.
  - Eric 

"The legitimate powers of government extend to such acts only as are injurious
 to others.  But it does me no injury for my neighbor to say there are twenty
 gods, or no God.  It neither picks my pocket nor breaks my leg."
                      [Thomas Jefferson]