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Old 04-05-2013, 03:43 PM   #7 (permalink)
kungfulu
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Join Date: Jan 2013
Location: Detroit, Mi
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Quote:
Originally Posted by chomps1211 View Post
Ok, I get all that. As I mentioned in op, I never took any reading of my max. speed to b 100% spot on. I always assumed that any logged speed would likely b +\- a few mph. So I suppose the argument being made by detractors of these apps. Are the flat out claims of top speed without acknowledging THAT discrepancy?

Or are people claiming that these apps. are unreliable and inconsitantly inaccurate enough that ANY given speed is questionable?
Additionally, that still doesn't address my observation that similar apps used when I ride my MTB seem to B reasonably close to the milage & mph's logged with my bike mounted odometer! Again, usually anywhere within 3-5 mph. Any time I've encountered larger variences than that, they can usually b traced to signal loss or interference.

That level of accuracy is good enough for me to be reasonably confidant that I'm not making wildly inflated, bullshit claims for my snowboarding speeds. Are we arguing about split hairs here?
I don't think they are inconsistently inaccurate. I think they are consistently accurate for how it is being logged. To your point of signal drop...that could be a huge factor in the results, solar flares can alter GPS readings…the list goes on. Even a half a second drop of not logging would throw the math off of how these track and would change the +/- big time. Each app creator uses a different algorithm based off of how they are tracking and how they built the app. You could take 3 different apps, load them on 3 iPhones and throw all three in a backpack, bomb down the mountain and when you pulled them out, they would probably all have a different number. The closest you could get to the real number is using the same app on the same phone over and over and that is because it would use the same way of collecting over and over.
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