Multi-loop course splits

jimgerweckMember

I'm measuring a course for a 30K this weekend. It consists of 3X a loop that I've determined through adding measured segments to be 10,0005m. There's a small road off the loop that can be used for a finish area, distance adjustable (but not more than 150m or so). It doesn't seem I'll be lucky enough that the mile or 5K splits will be the same on any loop, but I'm looking for suggestions on measuring it and doing the math to lay out all the splits on the first ride (I've already ridden all the segments, so this would be the second ride that's required to certify).

My plan is ride from an arbitrary finish to the loop, take a reading, then calculate the splits for each loop based on a 10,005m length. If my second ride comes up w/ a different distance, I'll adjust the splits if it's significant, but otherwise probably just leave them if they're w/in a few feet.

Any thoughts?

9/18/089:52 AM

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Original Post

peteriegelRCMBB Founder

Jim, I’d treat it as an exact 10 km loop except for a final adjustment. Pick a place for a finish, located on the loop itself. Be sure you have a bit of space to play with, because the finish will be adjusted when you are done. You will have no need for the road that leaves the loop, although you can use it for a finish if you want.

Figure your layout constant when you finish your calibration runs. It will include 1.001. Multiply this by 1.0005. This will make the splits nice and even on your 10005 meter loop. The start/finish will be 0, 10, 20 and 30 km. A point opposite on the loop opposite the start will be 5, 15 and 25 km.

Metric splits would be ideal here, and there would be no offsets involved. 2 km would also be 12 km and 22 km, 7 km would also be 17 km and 27 km. If you want to lay out mile splits, go ahead. Remember to assume that the loop is 10000 meters.

When you have recalibrated, figure your REAL constant. You will find that the loop now comes out to either 10005 meters or something a small amount different. Make the 30 km final adjustment based on the real final value for the calibration.

The course will likely be about 15 meters too long. Make the adjustment at the finish, as this will assure that all the previous splits are at least the proper length.

I don’t see 15 meters over 30 km as likely to give anyone hives on the intermediate splits, and the overall distance can be spot on.

9/18/081:01 PM

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