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10 replies

Setback from curb for cal course

duanerussellduanerussellMeasurer
No posts in Calibration for over a year, then Pete and I post within a day. Don't miss Pete's discussion, as it is good.

I was talking about calibration courses with a few measurers a few days ago, and we discussed setting a calibration course. The manual says to put it within a foot of a curb, or on a straight stripe, so you can ride a straighter line. Hmmm.

Aren't we calibrating for measuring a course on a road? Due to SPR, we won't be riding next to a curb for much of the route. It seems to me that riding next to a curb on calibration rides is unnaturally guiding us for a straight line.

Wouldn't a calibration ride be more reflective of our riding method (wobbly or straight) if we set the cal course 8' from the curb? This way, we ride what we believe to be a straight line, just as we do on the full-course measurement. This would give us a more-accurate clicks/km calculation than an artificially-straight line during calibration. Plus, if cars are parked on your cal course, you would still have access to your nail endpoints.

Just trying to think about why we do what we do, in all aspects of measuring, and if there may be a better way to do it.
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peteriegelpeteriegelRCMBB Founder
Check out this cal course

Cal course

It's about to expire this year and Dave Heithaus and I will remeasure it.

It's got the one-foot-from-the-curb nails, and also another set offset 8 feet toward the center of the road. Tom Riegel and I created it that way so we would not have to deal with parked cars or piles of leaves in the street.

The street has very little traffic.

Dave and I have both used this course a lot. I don't know about Dave, but I never had detectable differences when riding both courses at the same calibration occasion.

The original course was measured in the mid 1980's and did not include the offset course near the middle of the road.
B bobthurstonMember
I think that is brilliant, getting that offset that way. If you don't want to have a lengthwise offset as in this example, you could use the same technique with a couple additional measurements.

I think the amount of traffic on a road is important to know. I have a course set 8' from a roadway; you can always ride it with traffic, but sometimes not easily against traffic. Most of the problem is when one end of the course has NO parked cars; drivers will just naturally expect you to be over near the curb, not 8' out from it.

To Duane's initial question, should we purposely put cal courses where there is NOT a straight line to follow, I would answer no. Even though this is what we do in measuring the course (use our best judgement and eyesight to measure straight lines), we do want our measurements to be based on something "solid", and in this case a good cal course with a line that we can follow or be guided by. That said I have laid out a number of cal courses at what I expect will be outside of parked cars, and I don't think there is a huge problem in riding a straight line when calibrating.
duanerussellduanerussellMeasurer
Pete,

Thanks for sharing your experiences with the offset courses. Interesting that there is no difference in clicks on each course.

Bob, how can an artificially-guided straight line be considered "solid", if actual rides are not as true? If someone could not ride a straight line without a curb/line to follow, then every course they measure will be short, if they calibrate straight, but measure with curved "straights". That's my point.

Yes, many riders can ride a true line, as Pete has shown (only if rides on both courses are the same # of clicks, though. No deviation in clicks is allowed, if one is to say "no difference"). I would bet there are almost as many new measurers, though, that don't ride a true line, until they have paid attention to their riding for a while.
B bobthurstonMember
I want to throw this out there: calibrating is a great opportunity to practice riding straight. We should encourage newer measurers to take some time to do a LOT of calibration rides, challenging themselves to get the least possible number of counts, and to get consistency.

After watching newer measurers calibrate, I think many will not ride all that straight even when the cal course is right next to a straight line. In my opinion the line won't make them artificially ride too straight, but will help them gradually get better at riding a straight line. Eventually I think most will be able to just focus on a target, as Mark says.

One "danger" is that riders might look at the line too close to their own position, like right next to their wheel. Makes it very hard to ride straight, as opposed to aiming at some distant point.
peteriegelpeteriegelRCMBB Founder
Just for grins I tried and succeeded in viewing the painted marks on the Kirkham Road calibration course, using Google Earth. They don't show in the overhead view, but with a small amount of diddling with Street View you can see all four marks. I was hoping to be able to check the length using Google Earth, but alas! Trees obscured the overhead view.

If you take a look at 3354 (my house) you can even see me fiddling under the hood of my car in the driveway. I didn't notice the Google vehicle going down the street taking pictures.

It occurs to me that I may have set a modest world record, as being the first to identify and publish his or her image on Google Earth. I will claim the record, awaiting a counter-claim. It's not the South Pole or Everest, but one does what one can.
Last edited by peteriegel
kevinplucaskevinplucasMember
I also like and use the idea of marking the tape lengths with paint. Along the side of the masking tape that marks the tape length I’ll spray a paint line. The paint lines give me four intermediate marks to help guide my calibration rides – I use a 200 foot tape.

Straight and curbed calibration course or not, a measurer must still find calibration ride agreement within 2-3 counts.

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