GPS vs Bike Computer

toby_winkler
toby_winkler Posts: 1,298
edited May 2010 in MTB general
Right, so the other day I bought one of the Bike Computers from Aldi for £4.99. Mostly when I am riding I use a GPS tracking aplication on my phone (My Tracks For Android by Google). So I thought this morning I would use both of these and see how close the results where on a short ride round my local trails (which includes a short road ride to get to said trails). The results where as follow (And yes I know I am not the quickest before anyone says anything!):

GPS

Total Distance: 14.81 miles
Total Time: 1:24:53
Moving Time:1:19:48
Average Speed: 10.39 mph
Average Moving Speed: 11.14 mph
Max Speed: 24.61 mph

Bike Computer

Total Distance: 15.5 Miles
Total Time: 1:18:31
Average Speed 12 mph
Max Speed: 26.5 mph

Obviously the results where never going to be exactly the same, but out of the two which do you think is more accurate? Personally I would have thought the GPS would be better, but surely if the Bike Computer is set up properly (which it is) then surely that should be more accurate?

Personally I already prefer the Bike Computer as it said I went further in a shorter time ;)
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Comments

  • Oxygen Thief
    Oxygen Thief Posts: 649
    The part I don't get and the same happened to me today is the travel times are different. Now my GPS one doesn't stop until I tell it too I know that. But I also know that I never stopped until i arrived at work where I turned off my GPS one and th bike one should stop itself, a few seconds later maybbe but stil. The trip times were voer a minute different?!?!? WTF?!?!?!?
  • SCARFACExxx08
    SCARFACExxx08 Posts: 58
    I would say your bike computer is more accurate, for example if you're going up a steep hill will the GPS realise how long that road is? or does it work out point to point? Do you get what i'm trying to say here?
  • toby_winkler
    toby_winkler Posts: 1,298
    edited May 2010
    SCARFACExxx08 wrote:
    I would say your bike computer is more accurate, for example if you're going up a steep hill will the GPS realise how long that road is? or does it work out point to point? Do you get what i'm trying to say here?

    Yeah I understand what your trying to say here, hadn't thought about it actually! The GPS programme on my phone actually measure altitude, elavation gain etc, so in some way it must be able to eliminate the problem you are talking about?
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  • SCARFACExxx08
    SCARFACExxx08 Posts: 58
    What app are you using? i'll download it and try it in a bit
  • Oxygen Thief
    Oxygen Thief Posts: 649
    Bike computer's gotta be more accurate. GPS is very tempremental. Only thing that's dodgy ona bike comp is the cal works outs etc. How do they know if I'm going 30mph down a hill burning nothing or 10mph up a steep one and burning loads!
  • Oxygen Thief
    Oxygen Thief Posts: 649
    Toby_Winkler wrote:
    SCARFACExxx08 wrote:
    I would say your bike computer is more accurate, for example if you're going up a steep hill will the GPS realise how long that road is? or does it work out point to point? Do you get what i'm trying to say here?

    Yeah I understand what your trying to say here, hand thought about it actually! The GPS programme on my phone actually measure altitude, elavation gain etc, so in some way it must be able to eliminate the problem you are talking about?

    I know the app I use works out your altitude so it should account for this rather than do it point ot point.
  • toby_winkler
    toby_winkler Posts: 1,298
    SCARFACExxx08 wrote:
    What app are you using? i'll download it and try it in a bit

    My Tracks by Google for Android.
    jonbonjovial wrote:
    Bike computer's gotta be more accurate. GPS is very tempremental. Only thing that's dodgy ona bike comp is the cal works outs etc. How do they know if I'm going 30mph down a hill burning nothing or 10mph up a steep one and burning loads!

    I would never trust the calorie count on a bike computer, mine said I burned 970 today? Don't know if that sounds about right or not, seems quite high to me, but I am probably totally wrong.
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  • Oxygen Thief
    Oxygen Thief Posts: 649
    I think it'd take me 20plus to burn that much. Depends on your weight etc. But there's no way it knows what incline/decline your on so it shouldn't even bother trying to calculate it.
  • toby_winkler
    toby_winkler Posts: 1,298
    jonbonjovial wrote:
    I think it'd take me 20plus to burn that much. Depends on your weight etc. But there's no way it knows what incline/decline your on so it shouldn't even bother trying to calculate it.

    Yeah I'm not quite sure how it is meant to accurately work out how many calories you have burned, I suppose its just some sort of guideline for the fitness freaks.
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  • myopic
    myopic Posts: 692
    Bike computer will only be accurate in properly calibrated: the radius/diameter or the wheel need to be right - if your tyres are soft then when you get on the bike the wheel size will effecitvly become smaller and you will overestimate the distance covered and speed. 1/2 inc difference will affect accuracy of bith by about 4%.

    Regaridng GPS accuracy, GPS readings often do not take changes in altitude into account, even if the system measures altitude. If its a mobile phone type app, then that won't be as accurate as a proper satnav

    So I would say if you want to measure distance and speed, your bike computer should be the most accurate IF it is properly set-up
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  • Mccraque
    Mccraque Posts: 819
    I trialled the two side by side at the weekend over 27.5 miles. Both were within 0.1 miles of eachother and the times were pretty similar. I've a garmin foretrex 401 - which is great on the altitude as well because is designed for skiing too.

    As per the above. if you use the quick set up on the bike computer, the tyres may be slightly out - even tread patterns can affect it as well as how hard your tyres are

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