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Joseph Hebert
03/10/12 16:03
Read: 221 times
Okemah, Ok
United States


 		 #186568 - Not at all.
Responding to: Per Westermark's previous message
I am not wrong. My "formula" is the definition of a Watt. If you end where you start from there will be no accumulation of potential energy. As for the drag factor, it's a loss that you can correct for. If I were going to do so I would determine my cross section and consider it a constant, and then measure the wind speed. Drag losses are a non-linear function of wind speed, but that shouldn't be a problem for a computer to calculate in real time.

Measuring the force applied to a pedal is a much more complex approach to this problem. The amount of force you apply will vary greatly with sprocket ratios. If you only want to measure force exerted that's fine, but if you want to measure watts it's going to be much more problematic.

Any approach will require some loss correction, to whatever degree of accuracy you desire. I think those corrections should rely on the simplest measurments (as in the most accurate, easily obtained and fewest in number) possible.

I don't know how negligible rolling friction losses (tires and roads, chains and sprockets, bearings and axels, etc.) would be. That would have to be the subject of more deliberation.

Joe

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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