Did I really got that fast?

Discussion in 'Cycling Equipment' started by William H. O'Ha, Mar 8, 2004.

  1. I just finally put the ole Schwinn tourer in the corner. I
    got a new Motobecane Grand Record 27 speed with a mixed bag
    of componentry for a decent price. I got the Motobecane with
    a Sigma 1400BC computer. The settings in the computer were
    2155. It gave me a maximum speed of 47.9 mph. I was using
    700 x 23 tires. So I changed the number to 2133; as I saw
    this number in the manual. I got a maximum speed of 45 mph.
    My cadence when I check it varies at numbers such at 88 to
    90. I have occassion seen it up to 120. There appears to be
    no maximum cadence record in the computer. This is from spot
    readings as I bicycle. I did all of this in about 50 miles,
    yesterday. Does anyone the MPH and cadence numbers are
    accurate? I am for shocked by them.

    tnx

    --
    William H. O'Hara KB1IUB use QRZ.com for address lookup
     
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  2. Cipher

    Cipher New Member

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    (You get these readings cranking down a hill?) I would start out by determining the true circumference of your wheel. (You can use the directions from the CatEye site to determine this).

    http://www.cateye.com/manuals/MT300N v2_E.pdf

    What do you have for a rear cassette, (11-23, 12-25 etc.) and large front chain ring anyway?

    You may also be interested in plugging in the cassette/chain-ring combo on this site:

    http://www.sheldonbrown.com/gears/

    Let us know what you come up with.
     
  3. Werehatrack

    Werehatrack Guest

    On Tue, 09 Mar 2004 00:36:02 -0000, "William H. O'Hara, III"
    <[email protected]> may have said:

    > Does anyone the MPH and cadence numbers are accurate? I am
    > for shocked by them.

    Are you sure it's not reading kph instead of mph?

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Typoes are not a bug, they're a feature.
    Words processed in a facility that contains nuts.
     
  4. Dave Lehnen

    Dave Lehnen Guest

    William H. O'Hara, III wrote:

    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.
    >
    > tnx
    >
    >

    Sorry, you probably didn't. Most likely you went
    47.9 Km/hr, even though the display was set to MPH. Sigma
    computers are unusual in that when using MPH rather than
    Km/hr, you need to fudge the wheel circumference by the
    appropriate factor, 1.609344 if you want all the digits.
    If the 2133 number were correct, the adjusted number
    would be 1325. The Sigma manual explains this if you read
    the fine print. Most computers handle the conversion in
    their software, but not Sigma.

    You'll also most likely find, if you do a good calibration,
    that the effective circumference for a 700 x 23 is more like
    2095 than 2133, but that can vary with tire, rider weight,
    pressure, rim width, etc. 1302 would be the Sigma setting
    equivalent to 2095.

    Dave Lehnen
     
  5. Rick Onanian

    Rick Onanian Guest

    On Tue, 09 Mar 2004 00:36:02 -0000, "William H. O'Hara, III"
    <[email protected]> wrote:
    >the computer were 2155. It gave me a maximum speed of 47.9
    >mph. I was using 700 x 23 tires. So I changed the number to
    >2133; as I saw this number in the manual. I got a maximum
    >speed of 45 mph. My cadence when I check it varies at
    >numbers such at 88 to 90. I have occassion seen it up to
    >120. There appears to be no maximum

    See http://www.sheldonbrown.com/gears/ for a calculator.

    For your 700x23 tires, if you have a 53 tooth large ring and
    a 11 tooth small sprocket, you will indeed get 45.2 mph at
    120 rpm. Is your bike equipped with those gears?
    --
    Rick Onanian
     
  6. Harris

    Harris Guest

    William H. O'Hara, III <[email protected]> wrote:
    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.

    Were the average speed and distance numbers reasonable? Did
    you downhill pedaling real fast in your highest gear? If so,
    it's possible that you went 47.9 mph.

    As others have suggested, you may be reading kph rather
    than mph, but I would think that would also give you
    distance in km.

    Another possibility is that you had a problem with either
    the wheel sensor or the connection between the computer and
    the mount. I once got a reading of something like 85 mph
    when I know i wasn't going more than 30 mph. After I
    checked/corrected the wiring, the bogus readings ceased.

    Art Harris N2AH
     
  7. Harris

    Harris Guest

    William H. O'Hara, III <[email protected]> wrote:
    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.

    Were the average speed and distance numbers reasonable? Did
    you downhill pedaling real fast in your highest gear? If so,
    it's possible that you went 47.9 mph.

    As others have suggested, you may be reading kph rather
    than mph, but I would think that would also give you
    distance in km.

    Another possibility is that you had a problem with either
    the wheel sensor or the connection between the computer and
    the mount. I once got a reading of something like 85 mph
    when I know i wasn't going more than 30 mph. After I
    checked/corrected the wiring, the bogus readings ceased.

    Art Harris N2AH
     
  8. Harris

    Harris Guest

    William H. O'Hara, III <[email protected]> wrote:
    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.

    Were the average speed and distance numbers reasonable? Did
    you downhill pedaling real fast in your highest gear? If so,
    it's possible that you went 47.9 mph.

    As others have suggested, you may be reading kph rather
    than mph, but I would think that would also give you
    distance in km.

    Another possibility is that you had a problem with either
    the wheel sensor or the connection between the computer and
    the mount. I once got a reading of something like 85 mph
    when I know i wasn't going more than 30 mph. After I
    checked/corrected the wiring, the bogus readings ceased.

    Art Harris N2AH
     
  9. Harris

    Harris Guest

    William H. O'Hara, III <[email protected]> wrote:
    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.

    Were the average speed and distance numbers reasonable? Did
    you downhill pedaling real fast in your highest gear? If so,
    it's possible that you went 47.9 mph.

    As others have suggested, you may be reading kph rather
    than mph, but I would think that would also give you
    distance in km.

    Another possibility is that you had a problem with either
    the wheel sensor or the connection between the computer and
    the mount. I once got a reading of something like 85 mph
    when I know i wasn't going more than 30 mph. After I
    checked/corrected the wiring, the bogus readings ceased.

    Art Harris N2AH
     
  10. William H. O'Hara, III wrote:

    > I just finally put the ole Schwinn tourer in the corner. I
    > got a new Motobecane Grand Record 27 speed with a mixed
    > bag of componentry for a decent price. I got the
    > Motobecane with a Sigma 1400BC computer. The settings in
    > the computer were 2155. It gave me a maximum speed of 47.9
    > mph. I was using 700 x 23 tires. So I changed the number
    > to 2133; as I saw this number in the manual. I got a
    > maximum speed of 45 mph. My cadence when I check it varies
    > at numbers such at 88 to 90. I have occassion seen it up
    > to 120. There appears to be no maximum cadence record in
    > the computer. This is from spot readings as I bicycle. I
    > did all of this in about 50 miles, yesterday. Does anyone
    > the MPH and cadence numbers are accurate? I am for shocked
    > by them.

    Multiply by 0.6214. Sigma computers only understand km/h and
    the mph indicator is not linked to the calculation engine.
     
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