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03/12/12 22:02
Modified:
  03/12/12 22:21
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 		 #186623 - This was addressed earlier
Responding to: Joseph Hebert's previous message
But yes, the power will be cyclic because of what you just mentioned. However, you may note that the ride is still smooth. You just indirectly mentioned conservation of momentum. Kind of like why does a 4 cylinder car and an 8 cylinder car ride just as smooth? The flywheel keeps a steady pace.

I believe someone mentioned the answer as to just frequently sample. Which is a good approach.

But you did also mention another idea, however, power is greatest when applied at either 3 or 9 depending on viewpoint because going reverse just causes the hub mechanism in the rear wheel to skip. So, regardless of where a measurement is taken, the measurement will be cyclic and an average or integral calculation should be used.

Another idea comes to mind, it is a bit silly. Old fashioned torque wrenches just measured deflection directly by having a bar that is attached to the center where torque is applied, but is left hanging in mid-air. This way when force is applied at the radius the bar does not move from center. Perhaps a high resolution radial encoder could be used in place of a strain gauge if attaching the gauge is a problem.

List of 61 messages in thread
TopicAuthorDate
bikey design challenge      Jez Smith      03/09/12 12:14      
   Only 400W?      Per Westermark      03/09/12 12:23      
      Its a bit different on the road      Jez Smith      03/09/12 12:34      
         Brilliant idea in the bath      Jez Smith      03/09/12 13:35      
            Might work      Per Westermark      03/09/12 13:51      
               well...      Jez Smith      03/09/12 14:33      
                  So you are yourself saying 400W is a bit low max scale      Per Westermark      03/09/12 14:43      
                     O.K then 500 watts      Jez Smith      03/10/12 00:56      
                        Battery      Per Westermark      03/10/12 05:11      
            Fun with strain gauges      Oliver Sedlacek      03/12/12 05:57      
         You sure?      Per Westermark      03/09/12 13:48      
   nice ride      Andy Peters      03/09/12 14:31      
      fanks      Jez Smith      03/10/12 00:54      
   Sigma Rox 9.1...      Kai Klaas      03/10/12 09:59      
      Sigma fake      Per Westermark      03/10/12 11:07      
         What do you expect for that price?      Kai Klaas      03/10/12 12:09      
            Head or tail wind? Or riding in a group or alone?      Per Westermark      03/10/12 12:38      
               Way overcomplicating this      Joseph Hebert      03/10/12 14:02      
                  Sensors      Steve M. Taylor      03/10/12 14:22      
                     how indeed      Andy Peters      03/11/12 12:37      
                  Wrong - you are totally missing the drag factor      Per Westermark      03/10/12 14:22      
                     Not at all.      Joseph Hebert      03/10/12 16:03      
                        Real manufacturers haven't found your idea simple...      Per Westermark      03/10/12 17:09      
                           Point made      Joseph Hebert      03/10/12 18:46      
                           Some of your points are just wrong      Justin Fontes      03/10/12 19:04      
                              Sounds like you expect an infinite acceleration      Per Westermark      03/11/12 06:49      
                                 Repeat post Ignore      Justin Fontes      03/11/12 11:39      
                                 I try for a constant power      Justin Fontes      03/11/12 11:52      
                                    Crank rpm - not back wheel rpm      Per Westermark      03/12/12 00:31      
                                       I got the two confused      Justin Fontes      03/12/12 10:37      
                                          Bandwidth + return channel      Per Westermark      03/12/12 12:07      
                        Oh dear, so many variable constants      Oliver Sedlacek      03/12/12 06:48      
                  rocket science      Maarten Brock      03/11/12 03:58      
                     So don't ignore them      Joseph Hebert      03/11/12 07:39      
                        Of course, it is...      Kai Klaas      03/11/12 08:18      
                           wireless      Joseph Hebert      03/11/12 08:36      
                              Costs...      Kai Klaas      03/11/12 12:59      
                                 cost      Joseph Hebert      03/11/12 13:39      
                                    Another problem      Joseph Hebert      03/12/12 21:14      
                                       This was addressed earlier      Justin Fontes      03/12/12 22:02      
                                       Multiple strain gauges      Per Westermark      03/13/12 00:53      
                                          Competitive bicycling      Justin Fontes      03/13/12 10:24      
                                             Pulse      Per Westermark      03/13/12 10:55      
                                                If I had the power meter      Justin Fontes      03/13/12 11:14      
                                                   Normalizing with heart beats cancels some errors      Per Westermark      03/13/12 12:39      
                                                      Just to get some data to look at      Jez Smith      03/15/12 03:37      
                                                         Jez ?      Steve M. Taylor      04/14/12 04:35      
                                                            Oh Noes!!!!!!      Jez Smith      04/14/12 10:58      
                                                            The plan is      Jez Smith      04/15/12 01:55      
                                                               Brum doesn't HAVE mountains      Steve M. Taylor      04/15/12 14:51      
                                                                  Ah yes but no but      Jez Smith      04/15/12 23:23      
                                                                  Actualy...      Jez Smith      04/15/12 23:35      
                                                   If I had a power meter...      Oliver Sedlacek      04/16/12 04:20      
                                                      Ive been testing things      Jez Smith      04/16/12 04:41      
                                                         Well, no      Steve M. Taylor      04/16/12 07:41      
                                                            all very well thank you Steve      Jez Smith      04/16/12 08:45      
                                                               Getting nasty      Steve M. Taylor      04/17/12 10:54      
                                                                  nasty ?      Jez Smith      04/20/12 12:09      
                                 More time than money if access to machinery      Per Westermark      03/12/12 00:57      
                                 Strain gauge elastic fixtures      Oliver Sedlacek      03/12/12 06:55      
                           Sure      Per Westermark      03/11/12 09:42      

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