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A weight question
Posted: Thu Feb 19, 2009 5:30 am
by cjonbike
Sorry if this has been covered but I could not find a thread through searching.
Say I weigh 160 lbs when I do my coast downs and cal ride, I then proceed to lose 10 lbs, can I just change my weight in the unit and profile and the unit will report the correct power, or do I need to do the coast downs and cal ride again?
Thanks for all help
Chris
Re: A weight question
Posted: Thu Feb 19, 2009 7:38 am
by mullerrj
No question, I'd redo the coast downs and cal ride. Rob
Re: A weight question
Posted: Thu Feb 19, 2009 12:08 pm
by rruff
If you have a really good cal then 10 lbs isn't enough to make it necessary. The only thing you'd expect to change is a slightly lower CdA.
On the other hand I think it is a good idea to do a cal every once in awhile anyway... just to make sure everything is working right.
Re: A weight question
Posted: Thu Feb 19, 2009 2:48 pm
by mullerrj
rruff..that's exactly the reason why I said I would do it..just to make sure everything is working properly..good stuff. Thanks Rob
Re: A weight question
Posted: Thu Feb 19, 2009 11:31 pm
by cjonbike
Thanks a bunch for your help
Chris
Re: A weight question
Posted: Fri Feb 20, 2009 12:21 am
by coachboyd
If you have a Gen 3 unit, you won't have to redo your cal ride. The cal ride just stores wind scaling and riding tilt in the unit. Those values are what makes it possible to get cda and crr from the aero and friction values.
So, you can just do a bunch of coastdowns, and use the previous stored wind scaling and riding tilt numbers and you will have a new profile! Wind scaling and riding tilt won't have changed, well riding tilt might have slightly but if you get a good crr number then you are good. Riding tilt is not as important as it used to be because of the tilt correction, but it is used in determining crr from the friction number. So as long as your crr is good, then your riding tilt can be slightly off.
Re: A weight question
Posted: Fri Feb 20, 2009 12:14 pm
by cjonbike
Thank you for the explanation Coach Boyd, liking this meter more and more all the time.
Chris