A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

What happens if you hang a weight from the bottom of a wheel?



 
 
Thread Tools Display Modes
  #1  
Old September 11th 06, 05:07 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 7,934
Default What happens if you hang a weight from the bottom of a wheel?

While I was enjoying the current incarnation of the stand-or-hang
thread, I found myself wondering what the spokes and the rim will do
if you stick a wheel up in the air and hang a weight from the rim
section that would normally be the contact patch.

Cheers,

Carl Fogel
Ads
  #8  
Old September 11th 06, 07:46 PM posted to rec.bicycles.tech
Dan
external usenet poster
 
Posts: 195
Default What happens if you hang a weight from the bottom of a wheel?

wrote:
While I was enjoying the current incarnation of the stand-or-hang
thread, I found myself wondering what the spokes and the rim will do
if you stick a wheel up in the air and hang a weight from the rim
section that would normally be the contact patch.

Cheers,

Carl Fogel


Dear CF

I am not completely clear on what the question is but if you are
thinking of a wheel, supported at the axle, with an outward radial force
applied to the rim to simulate the opposite of the inward radial loading
that a wheel usually sees while in use and the wheel is not a drive
wheel and brake is not applied and no spoke goes into compression ...

So long as the material remains elastic, exactly the opposite of what
happens with the usual loading.

If under the usual loading (UL) the tension in a particular spoke
decreases, the tension will increase when subjected to unusual (CF)
loading. This assumes that all material remains elastic and has linear
elasticity. Aluminum alloys do not truly have linear elasticity but for
the range of stress involved, which will be the case if the forces are
kept within a reasonable range, it is probably accurate enough to assume
linear elasticity for aluminum alloys. Steel is a very well behaved
material and displays very linear elasticity through compression and
tension. Some references provide a different modulus for aluminum alloys
in tension and compression but we won't go there unless someone can
support a theory of stress reversal in rims.

For UL, stress = (unloaded stress) + (delta stress)
For CF, stress = (unloaded stress) - (delta stress)

For UL, force = (unloaded force) + (delta force)
For CF, force = (unloaded force) - (delta force)

If anything goes into compression (total force or local stress), one
must consider stability. For a spoke I would use Euler's equation for
long slender columns.

Later,
Dan
  #9  
Old September 11th 06, 08:51 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,751
Default What happens if you hang a weight from the bottom of a wheel?

Carl Fogel wrote:

While I was enjoying the current incarnation of the stand-or-hang
thread, I found myself wondering what the spokes and the rim will do
if you stick a wheel up in the air and hang a weight from the rim
section that would normally be the contact patch.


View the rim as an elastically supported beam, as has been suggested
here previously. The effect, on a hub anchored wheel, is the same but
opposite of its normal loading. The bottom spokes get a bit longer
and the others react the inverse of before, because the diameter of
the rim decreases slightly (making other spokes have slightly less
tension than initially).

Of course we can expect arguments why the load is hanging from the top
spokes from some quarters.

Jobst Brandt
  #10  
Old September 14th 06, 01:57 PM posted to rec.bicycles.tech
Dave
external usenet poster
 
Posts: 7
Default What happens if you hang a weight from the bottom of a wheel?

wrote in message
...
While I was enjoying the current incarnation of the stand-or-hang
thread, I found myself wondering what the spokes and the rim will do
if you stick a wheel up in the air and hang a weight from the rim
section that would normally be the contact patch.

Cheers,

Carl Fogel


Nothing as long as you hold onto the wheel. Let go and both the wheel and
the weight fall to the ground.

Care to rephrase the question?


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
New bicycle idea Bob Marley General 49 October 7th 04 05:20 AM
Which Tire Loses Traction First? [email protected] Techniques 489 September 22nd 04 08:52 PM
Spoke Over-Tension and Drifting Wheel Alignment mCrux Techniques 6 August 25th 04 04:29 PM


All times are GMT +1. The time now is 02:37 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.