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???
03/13/12 03:14
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 		 #186620 - Another problem
Responding to: ???'s previous message
Another problem occurs to me. If you put strain gauges in the pedals the portion of the total force vector that contributes to torque will vary sinusoidally. When the pedal is at 12:00 and 6:00 the total force applied to the pedal is parallel to the radius of rotation and contributes zero to the torque. At 9:00 and 3:00 the force applied to the pedal is normal to the radius of rotation and contributes fully (vector addition, ±) to the torque.

I suppose this could be calculated in firmware, but I think a better approace would be to outfit the strain gauge(s) somehow on the sproket. It's just a thought, in case anyone is actually planning to do this.

Joe

List of 61 messages in thread
TopicAuthorDate
bikey design challenge            01/01/70 00:00      
   Only 400W?            01/01/70 00:00      
      Its a bit different on the road            01/01/70 00:00      
         Brilliant idea in the bath            01/01/70 00:00      
            Might work            01/01/70 00:00      
               well...            01/01/70 00:00      
                  So you are yourself saying 400W is a bit low max scale            01/01/70 00:00      
                     O.K then 500 watts            01/01/70 00:00      
                        Battery            01/01/70 00:00      
            Fun with strain gauges            01/01/70 00:00      
         You sure?            01/01/70 00:00      
   nice ride            01/01/70 00:00      
      fanks            01/01/70 00:00      
   Sigma Rox 9.1...            01/01/70 00:00      
      Sigma fake            01/01/70 00:00      
         What do you expect for that price?            01/01/70 00:00      
            Head or tail wind? Or riding in a group or alone?            01/01/70 00:00      
               Way overcomplicating this            01/01/70 00:00      
                  Sensors            01/01/70 00:00      
                     how indeed            01/01/70 00:00      
                  Wrong - you are totally missing the drag factor            01/01/70 00:00      
                     Not at all.            01/01/70 00:00      
                        Real manufacturers haven't found your idea simple...            01/01/70 00:00      
                           Point made            01/01/70 00:00      
                           Some of your points are just wrong            01/01/70 00:00      
                              Sounds like you expect an infinite acceleration            01/01/70 00:00      
                                 Repeat post Ignore            01/01/70 00:00      
                                 I try for a constant power            01/01/70 00:00      
                                    Crank rpm - not back wheel rpm            01/01/70 00:00      
                                       I got the two confused            01/01/70 00:00      
                                          Bandwidth + return channel            01/01/70 00:00      
                        Oh dear, so many variable constants            01/01/70 00:00      
                  rocket science            01/01/70 00:00      
                     So don't ignore them            01/01/70 00:00      
                        Of course, it is...            01/01/70 00:00      
                           wireless            01/01/70 00:00      
                              Costs...            01/01/70 00:00      
                                 cost            01/01/70 00:00      
                                    Another problem            01/01/70 00:00      
                                       This was addressed earlier            01/01/70 00:00      
                                       Multiple strain gauges            01/01/70 00:00      
                                          Competitive bicycling            01/01/70 00:00      
                                             Pulse            01/01/70 00:00      
                                                If I had the power meter            01/01/70 00:00      
                                                   Normalizing with heart beats cancels some errors            01/01/70 00:00      
                                                      Just to get some data to look at            01/01/70 00:00      
                                                         Jez ?            01/01/70 00:00      
                                                            Oh Noes!!!!!!            01/01/70 00:00      
                                                            The plan is            01/01/70 00:00      
                                                               Brum doesn't HAVE mountains            01/01/70 00:00      
                                                                  Ah yes but no but            01/01/70 00:00      
                                                                  Actualy...            01/01/70 00:00      
                                                   If I had a power meter...            01/01/70 00:00      
                                                      Ive been testing things            01/01/70 00:00      
                                                         Well, no            01/01/70 00:00      
                                                            all very well thank you Steve            01/01/70 00:00      
                                                               Getting nasty            01/01/70 00:00      
                                                                  nasty ?            01/01/70 00:00      
                                 More time than money if access to machinery            01/01/70 00:00      
                                 Strain gauge elastic fixtures            01/01/70 00:00      
                           Sure            01/01/70 00:00      

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