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Sat Apr 5, 2014, 11:39 PM

Bike computer vs. phone app

Hi,
I've recently started using mapmyride phone app to track my biking. The thing is screwy, I ride the exact same route to work and home. The two trips end up with different mileage, but not by much. The difference between my bike computer and the phone app is strange too. It is .5 mile off on a 10 mile commute. I do like mapmyride because it uploads it to their website. I may try endomondo app soon and see what the difference is. Anyone have experience with some good free phone apps?

Peace

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Arrow 9 replies Author Time Post
Reply Bike computer vs. phone app (Original post)
hibbing Apr 2014 OP
NYC_SKP Apr 2014 #1
FLSurfer Apr 2014 #2
frylock Apr 2014 #3
hibbing Apr 2014 #4
happyslug Apr 2014 #5
hibbing Apr 2014 #6
jberryhill May 2014 #7
happyslug May 2014 #8
jberryhill May 2014 #9

Response to hibbing (Original post)

Sun Apr 6, 2014, 12:20 AM

1. Try runkeeper

 

It works well for me and is free.

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Response to hibbing (Original post)

Sun Apr 6, 2014, 09:40 PM

2. I currently use endomondo and have

For years. It occasionally hiccups and records a bit short or long or slow or fast but is generally very good.
However, I have a Kreyos Meteor smart watch on the way and understand it isn't compatible with endomondo, so I may also be looking for a new app.

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Response to hibbing (Original post)

Fri Apr 11, 2014, 03:42 PM

3. what platform are you on?

if you use Android, try using Google's My Tracks. It seems more accurate to me than MapMyRide.

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Response to hibbing (Original post)

Mon Apr 14, 2014, 11:32 PM

4. Android

Hi,
Thanks for the suggestions everyone, I'll check them out. Anyone else participate in the National Bike Challenge? It is kind of fun, it starts May 1.

https://nationalbikechallenge.org/about

The National Bike Challenge is a nationwide event uniting thousands of current bicyclists — and encouraging countless new riders. In its simplest form it is a logging center for users to record miles ridden and be part of the national community of bicyclists. It is a free and easy way to challenge yourself, colleagues and the greater community to ride more. Users compete on a local, state and national level. The Challenge aims to unite 50,000 riders to pedal 30 million miles from May 1, 2014 until September 30, 2014. Now in its third year, the Challenge is a successful partnership between the League of American Bicyclists and Kimberly-Clark’s Scott Natural Brand.

Peace

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Response to hibbing (Original post)

Wed Apr 23, 2014, 09:33 PM

5. I am sorry, but I am confused about your problem

 

I am confused for the difference may be the difference on what the two devices are measuring:

Reason for the difference: Situation one - the two tools you are using are measuring two different things:

I use an old fashion electronic "Computer" that uses a magnet on the wheel and counts the turns of the wheel to produce an accurate measurement of miles. I have an app on my phone that uses GPS to measure mileage. Given that the measurement may be off up to 100 feet I fully expect the two NOT to read the same.

The Wheel based system is measuring actual movement, the APP is measuring movement in relations to up to 23 satellites.

This is related to the difference between Acceleration and Instantaneous Acceleration. People tend to view them as the same thing, but they are different AND the measurements from both system tend to be close, but different.

A wheel base computer is using normal Acceleration, that is the increase in Velocity over a time period. Instantaneous Acceleration is what a Radar gun measures, how fast you are going that very instant. I suspect any GPS based mph system is measuring Instantaneous Acceleration over and over again. Thus it is constantly changing. The same with normal acceleration, as you speed up and slow down the "speed" being measured changes. You do not see it but each time the reader goes by the magnet you have a new normal acceleration, thus normal acceleration is also constantly changing.

http://physics.info/acceleration/

Thus the difference may be do to the simple fact you are using two different method of measuring your speed. These two systems are NOT the same nor are their measuring the same thing. Both uses mph (or Kph) but that is all they have in common. The numbers from both systems tend to be close, but rarely the same for their are measuring two different things.

Reason for the difference - Situation Two 0 - Errors in measurement

While a wheel based measurement system tends to be very accurate (in the sense it is constantly measuring the same thing, but at different speeds), GPS system have error rates based on the fact that it is receiving signals from Satellites, and the system was designed with an inherent error rate. Most GPS system can deal with this error rate, but it takes additional electronics that most people do not need. For example the Military has each Satellite use two different frequency, while the Civilian GPS only reads one of those frequency.

http://www.gps.gov/systems/gps/performance/accuracy/

As to most users of GPS, does it really matter if you are 10, 20 or 30 feet from where you want to be? As a biker you can quickly make up that difference.

We do not need that type of accuracy, most GPS system will determine if you off your route by the time you had driven 50 feet and make corrections. Many will correct to even closer tolerances if your GPS device has signals from all of the Satellites.

Side note: I do not have any first hand knowledge of the accuracy of GPS Systems. The US Government says high quality GPS receivers have an accuracy of 3 meters.

http://www.gps.gov/systems/gps/performance/accuracy/

I suspect most phones GPS is not that accurate, but 10 meters would be good enough for most biking or driving.

Please note, GPS has land based assistance programs to make GPS more accurate on waterways and highways, such group assistance can put people within 10 centimeters of their correct position (these are located on Waterways and Highways in addition to Airports).

http://www.gps.gov/systems/augmentations/


Just pointing out the difference between your two devices may be that they are measuring two different things.

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Response to happyslug (Reply #5)

Wed Apr 23, 2014, 11:18 PM

6. Thanks for the additional information n/t

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Response to hibbing (Original post)

Thu May 8, 2014, 11:11 AM

7. My problem with phone apps generally....


Is that continuous GPS and data (and a little ride music) puts a strain on the battery. Yeah, I know I'm not supposed to listen to music while riding, but I don't use a sound-isolating headset (yurbuds sweat-proof) and I keep the volume reasonably low enough to hear ambient sounds.

Unless I have a 100% charge, the phone charge doesn't last as long as my ride, and then I lose emergency use of the phone. I've been thinking of just keeping a solar USB battery on the rear rack, but haven't decided whether to do that or just install a cyclocomputer.

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Response to jberryhill (Reply #7)

Thu May 15, 2014, 10:16 PM

8. Thought about a Generator????

 

I use to have that problem on long night rides, in the days of incandescent lights, the batteries would only last about 90 minutes. I solved that problem by going to generator lights.

Today's LED lights can last 5-9 hours between charging, that was NOT the case when incandescent lights were the only headlight you could get. Thus the Schmidt SON does not have the advantages it had as late as the early 2000s. Schmidt SON Generator is still a very good generator. I notice NO increase in resistance when I replaced the Shimano XTR front axle I had on my bike with a Schmidt SON generator. Schmidt claims they is some increase, I just could not see it when I was biking (and I bike with the light powered by the Generator ON at all times).

More on the SON itself:

http://www.peterwhitecycles.com/schmidt.asp

The SON can charge any electrical device using the following:

http://www.peterwhitecycles.com/ewerk.asp

Through one user said he could NOT get it to work with the Sumsung Galaxy:

http://www.velophile.com.au/2012/07/11/how-to-keep-your-electronic-devices-charged-while-on-tour-busch-muller-e-werk-overview/

The problem with the galaxy seems to be it wants a 5 watt constant charge, and with SON generator, when you stop, power drops and the phone shuts down. The solution APPEARS to be the need to have a Cache battery between the generator and the device. The Generator charges the Cache Battery which it turns charges the device being charged.

The E-werk cost $207 dollars, the Cache battery costs $102 dollars

Instead of relying on the Generator to Charge the Cache battery, you may want to charge it before any trip:
Ixon IQ Speed battery charger, Part # B&M4473: $ 41.00

Special cable needed for charging Cache Battery, Part # B&M461A44731: $ 9.75

Total. NOT including the SON Generator is $359,75.

The Schmidt SON Generator varies depending on the wheel you install it one, but the Generator itself starts at about $282 to $362. Wheel, Spokes and building the wheel etc would be extra. I have had one for over ten years, and have had no problem with the wheel (I had a previous wheel almost as long, but the generator died on me after about ten years of heavy use).

Thus you are looking at $800-1000 dollars for everything. Since I already have the Generator and lights I am thinking about it for it would only cost me about $360.00.

I do not know if the above would work for me, let alone you, but it is an option to think about.

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Response to happyslug (Reply #8)

Thu May 15, 2014, 10:46 PM

9. Looked at those

It's a lot more interesting than the one I had back in the 70's which had a wheel on a generator shaft biased to the tire. But I can't justify the cost.

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