speed= distance / time

ednino
ednino Posts: 684
edited September 2009 in Road beginners
I've just put some 26x1.2 conti grand prix tyres on my MTB to use it on road for commuting during the week.

Its taken me 28.30 minutes to get 7.8 miles to work across very hilly wales. How do i work out my average speed? I know the formula, but its the units that i can't figgure out lol

thanks :lol:

Comments

  • 28.30 minutes = 28.30/60 hours = 0.4717 hrs

    your average speed = 7.8miles / 0.4717 hrs = 16.54 mph

    tenbar
  • 28 minutes 30 seconds = 28.5 minutes

    Convert that into hours:
    28.5/60 = 0.475 hours

    Then calculate speed:
    7.8/0.475 = 16.4 mph
  • pllb
    pllb Posts: 158
    Well I work it out like this:

    Mileage/(time/60) - so 7.8/(28.3/60)=16.54 mph average

    Hope that helps :D
  • Who's right? Was it 28 minutes 30 seconds or 28 minutes 18 seconds?

    The excitement is killing me.
  • bompington
    bompington Posts: 7,674
    edited September 2009
    Just do 7.8 / 28.30 to get your speed in miles / minute: but in an hour you go 60X further than a minute so
    7.8 / 28.30 X 60 = 16.4mph

    On second thoughts sod this, just get a bike computer
  • It all depends if it was 30 seconds or 0.3 minutes. It's just like Eggheads this.
  • Lonzy
    Lonzy Posts: 26
    28.30 is 26 minutes 30 seconds which is 26 and a half minutes, not 26 and 3/10s

    16.4 mph
  • graeme_s-2
    graeme_s-2 Posts: 3,382
    Lonzy wrote:
    28.30 is 26 minutes 30 seconds which is 26 and a half minutes, not 26 and 3/10s

    16.4 mph

    I think you'll find that 28.30 is actually 28 minutes.... :D:lol:
  • Anonymous
    Anonymous Posts: 79,665
    This is the most interesting cake stop has been for ages.

    12 seconds......or not...ooohhh...the tension... :lol:
  • Anonymous
    Anonymous Posts: 79,665
    Did anyone notice my deliberate, accidentally on purpose istake then ?

    Go on, flame me...
  • DomPro
    DomPro Posts: 321
    Or if you're feeling REALLY lazy, simply type '7.8 miles in 23.5 minutes' into WolframAlpha search engine. It does all the work for you :D

    http://www.wolframalpha.com/
    Shazam !!
  • mikeq
    mikeq Posts: 141
    DomPro wrote:
    Or if you're feeling REALLY lazy, simply type '7.8 miles in 23.5 minutes' into WolframAlpha search engine. It does all the work for you :D

    http://www.wolframalpha.com/

    It'll give you an answer, not the correct one as you did it in 28.5 minutes, but it will give you an answer
    Cycling from Glasgow to Paris to raise funds for Asthma UK

    www.velochallenge.org
  • LOL

    Come on ednino was it 28.3 minutes or 28 minutes 30 seconds ??

    The difference between 16.54 and 16.4 mph is crucial
  • CiB
    CiB Posts: 6,098
    Keep it simple. My DB stores ride times as seconds, derived from the input form's three input fields, so (HH * 3600) + (MM * 60) + SS. To get the avg speed back it executes a query that returns (distance / seconds) * 3600 to get to hours.

    My normal commute:
    20.78m in e.g. 1h 3m 27s = 20.78m in 3807 seconds. (20.78 / 3807) * 3600 = 19.65mph.

    Yours equates to
    7.8 miles in (0 * 3600) + (28 * 60) + 30 = (7.8 / 1710) * 3600 = 16.42105 mph

    Easy. And bang on - no rounding errors with parts of hours or minutes.
  • ...but if he..weighs the same .......as a duck....and a duck floats........

    ...a witch !


    ...burn him....!
  • Keep it simple. My DB stores ride times as seconds, derived from the input form's three input fields, so (HH * 3600) + (MM * 60) + SS. To get the avg speed back it executes a query that returns (distance / seconds) * 3600 to get to hours.

    My normal commute:
    20.78m in e.g. 1h 3m 27s = 20.78m in 3807 seconds. (20.78 / 3807) * 3600 = 19.65mph.

    Yours equates to
    7.8 miles in (0 * 3600) + (28 * 60) + 30 = (7.8 / 1710) * 3600 = 16.42105 mph

    Easy. And bang on - no rounding errors with parts of hours or minutes.

    I believe there are rounding errors in there. My understanding is that your answer cannot have more decimal places then the value with the fewest decimal places. Though I could be wrong! :P
  • CiB
    CiB Posts: 6,098
    Well spotted. I went overboard with the decimal places just to make the point. In the db it rounds down to two places but there was no need to add complexity to the suggested answer on here. Good spot though. Take the rest of the morning off. :)
  • Keep it simple. My DB stores ride times as seconds, derived from the input form's three input fields, so (HH * 3600) + (MM * 60) + SS. To get the avg speed back it executes a query that returns (distance / seconds) * 3600 to get to hours.

    My normal commute:
    20.78m in e.g. 1h 3m 27s = 20.78m in 3807 seconds. (20.78 / 3807) * 3600 = 19.65mph.

    Yours equates to
    7.8 miles in (0 * 3600) + (28 * 60) + 30 = (7.8 / 1710) * 3600 = 16.42105 mph

    Easy. And bang on - no rounding errors with parts of hours or minutes.

    But I think you're assuming the OP posted 30 seconds. In which case you're correct but it could be 0.3 of a minute (18 seconds) in which case it would be 16.54mph :wink:

    Come on OP :wink:
  • will3
    will3 Posts: 2,173
    44 451.7314 furlongs per fortnight
  • CiB
    CiB Posts: 6,098
    Escargot wrote:
    But I think you're assuming the OP posted 30 seconds. In which case you're correct but it could be 0.3 of a minute (18 seconds) in which case it would be 16.54mph :wink:

    Come on OP :wink:

    No you're right there to highlight the ambiguity. OP stated 7.8 miles in 28.30 minutes, not 28:30. 28.3 minutes is, as stated, 28:18.

    We can only work with the data as supplied - it's not for us to second guess the format, or to assume that 28 point 3 really meant 28 point 5. Stick at 28:18 / 16.54

    Who says punctuation doesn't matter eh?

    :)
  • Escargot wrote:
    But I think you're assuming the OP posted 30 seconds. In which case you're correct but it could be 0.3 of a minute (18 seconds) in which case it would be 16.54mph :wink:

    Come on OP :wink:

    No you're right there to highlight the ambiguity. OP stated 7.8 miles in 28.30 minutes, not 28:30. 28.3 minutes is, as stated, 28:18.

    We can only work with the data as supplied - it's not for us to second guess the format, or to assume that 28 point 3 really meant 28 point 5. Stick at 28:18 / 16.54

    Who says punctuation doesn't matter eh?

    :)

    LOL

    Can't belive this thread is onto 2 pages of discussion over 0.12mph :D

    I apologise for being so pedantic but work is really dragging today :wink:
  • deal
    deal Posts: 857
    dont forget that it needs to be converted to kph so you can be like the continental chaps, plus 26.6 kph sounds faster than 16.5 mph!
  • ednino
    ednino Posts: 684
    thanks for all the help :lol:

    Its was 28 minutes 30 seconds :wink:

    So 16.4mph

    Im happy with that, i'll do a 10 mile blast on the flat later to see what im doing without all the hills to slow me down 8)
  • ednino
    ednino Posts: 684
    17.9mph on the flat

    not as much difference as i expected
  • Lonzy
    Lonzy Posts: 26
    That's more than you think... think Contador won a month long race by a few minutes!
  • CiB
    CiB Posts: 6,098
    That is quite a difference. if you'd set off against yourself you'd be a mile & a half further up the road after an hour. Or in reverse terms, you'd do that 7.8 miles about 1m 15s faster.

    You don't see huge jumps in performance, just steady incremental diffs that accumulate. Soon a 16.4 mph avg will seem like a bimble to the shops.