Run Run Away

Question:

Some slipage can occur when using a wheel on soft surfaces, but the difference you sight is substantial. Compare how it measures against a 100 foot tape on a hard surface, then try it on grass. A variance of 20% will be noticable in just 100 feet. Rich — Posted from c1240929-a.fedwy1.wa.home.com [24.176.2.121] via Mailgate.ORG Server – http://www.Mailgate.ORG

Response:

- Hide quoted text — Show quoted text -We have been attempting to lay out a high school cross-country running route.  We have a measuring wheel, but we seem to be getting inconsistent measurements. Does a measuring wheel loose its usefulness on grass?  Does it become inconsistent when rolled over a grassy surface? The problem we seem to be facing is that the wheel ALWAYS indicates that it has not travelled as far as it actually has. We have been measuring a course that we feel has been accurately measured in the past as being 15,206 feet.  Our measurements with this wheel gives a reading of about 12,080 feet.  Thats a substantial difference.!!! We have determined that the counter on the wheel never stops counting…..as long as the user is walking, the counter is counting. The only thing we can think of is that this wheel just does not give a true reading when used on grass.  About 60% of the course we are measuring is grass. Anyone have any comments or input on this? Thank you…….      Lee Carkenord

For all the courses I’ve ever laid out, I’ve used a bike with a cyclocomputer…they only cost $15-$30 for a basic model and it’ll measure in kilometers and miles. (usually to the hundreth). Joe

Response:

That’s about a 20% difference!  Does the wheel measure directly in feet, or does it count revolutions?  If it counts revolutions, make sure the factor for converting to feet is correct. Maybe you could try measuring a length of grass with a tape measure (a football field, for example) and the measuring with the wheel.  If the wheel is not tracking correctly on the grass, this test should reveal the discrepancy. Also measure on a running track.  It’s possible that the counter has been calibrated for a wheel of a different diameter. Of course, a final possibility is that the previous measurement was incorrect.  What kinds of times were you getting on this course?

– Hide quoted text — Show quoted text -We have been attempting to lay out a high school cross-country running route.  We have a measuring wheel, but we seem to be getting inconsistent measurements. Does a measuring wheel loose its usefulness on grass?  Does it become inconsistent when rolled over a grassy surface? The problem we seem to be facing is that the wheel ALWAYS indicates that it has not travelled as far as it actually has. We have been measuring a course that we feel has been accurately measured in the past as being 15,206 feet.  Our measurements with this wheel gives a reading of about 12,080 feet.  Thats a substantial difference.!!! We have determined that the counter on the wheel never stops counting…..as long as the user is walking, the counter is counting. The only thing we can think of is that this wheel just does not give a true reading when used on grass.  About 60% of the course we are measuring is grass. Anyone have any comments or input on this? Thank you…….      Lee Carkenord

Response:

We have been attempting to lay out a high school cross-country running route.  We have a measuring wheel, but we seem to be getting inconsistent measurements. Does a measuring wheel loose its usefulness on grass?  Does it become inconsistent when rolled over a grassy surface? The problem we seem to be facing is that the wheel ALWAYS indicates that it has not travelled as far as it actually has. We have been measuring a course that we feel has been accurately measured in the past as being 15,206 feet.  Our measurements with this wheel gives a reading of about 12,080 feet.  Thats a substantial difference.!!!

Is that a typo? Did you mean 15,080 feet? If not, you could probably do about as well by pacing off the course. We have determined that the counter on the wheel never stops counting…..as long as the user is walking, the counter is counting. The only thing we can think of is that this wheel just does not give a true reading when used on grass.  About 60% of the course we are measuring is grass. Anyone have any comments or input on this?

Find a track with grass around the outside or inside. Measure around the track with your wheel, then measure the offset of your radius from the measured line on the track and do the math to figure the true distance. This should confirm whether your wheel is measuring long, and by how much. Alternatively, steel tape a 1000 foot section of the course and see what measurement the wheel gives over that segment. (1000 feet is the minimum length allowed by USATF for calibration courses.) Using a wheel on a rougher surface than the one it is calibrated for would produce measurements that show a course to be shorter than it really is.  The wheel would tend to lose contact with the surface and not spin as much as it should. — Terry R. McConnell   Mathematics/304B Carnegie/Syracuse, N.Y. 13244-1150

Response:

We have been attempting to lay out a high school cross-country running route.  We have a measuring wheel, but we seem to be getting inconsistent measurements. Does a measuring wheel loose its usefulness on grass?  Does it become inconsistent when rolled over a grassy surface? The problem we seem to be facing is that the wheel ALWAYS indicates that it has not travelled as far as it actually has. We have been measuring a course that we feel has been accurately measured in the past as being 15,206 feet.  Our measurements with this wheel gives a reading of about 12,080 feet.  Thats a substantial difference.!!! We have determined that the counter on the wheel never stops counting…..as long as the user is walking, the counter is counting. The only thing we can think of is that this wheel just does not give a true reading when used on grass.  About 60% of the course we are measuring is grass. Anyone have any comments or input on this? Thank you…….      Lee Carkenord

Response: