We suggest you first print the questions below as two pages for easy reference.

Use the following two pages which are formatted for printing: Q1-Q5 and Q6

Work though the 6 questions. You should refer back to the introductory lessons if you are not sure of any answer. Then recheck every calculation completely. If you make a significant numerical mistake you will fail the test. Write out the answers very briefly in an email and send it to If you are successful you will be allowed onto the next stage of the course.

1. The following are the results of rides on calibration courses before and after measurements.

1.1 Calibration course length 400m.
Pre-measurement calibration - Ride 1: 64252.5 to 68616, Ride 2: 68616 to 72980, Ride 3:72980 to 77344, Ride 4: 77344 to 81709
Post-measurement calibration - Ride1: 62807.5 to 67172, Ride2: 67172 to 71537, Ride3: 71537 to 75901, Ride4: 75901 to 80266.5

1.2 Calibration course length 695.254m.
Pre-measurement calibration - Ride 1: 81399 to 88984, Ride 2: 88984 to 96569, Ride 3: 96569 to 04154, Ride 4: 04154 to 11740.5
Post-measurement cal - Ride 1: 25329 to 32915, Ride 2: 32915 to 40501.5, Ride 3: 40501.5 to 48087.5, Ride 4: 48087.5 to 55674

1.3 Calibration course length 0.5 miles
Pre-measurement calibration - Ride 1: 72473 to 81623, Ride 2: 81834 to 90984, Ride 3: 91179 to 00329, Ride 4: 00527 to 09674
Post-measurement cal - Ride 1: 51586 to 60735, Ride 2: 60801 to 69949, Ride 3: 70069 to 79217, Ride 4: 79340 to 88487

In each case calculate

a) the pre-measurement constant,
b) the post-measurement constant, and
c) the constant of the day (in counts/km).

2. Now recalculate the 3 pre-measurement calibration constants from question 1 as counts per mile.

3. The following are the results from measuring the Cranleigh Course which is approximately 15 miles.

Calibration course length 330m
Pre-measurement cal - Ride 1: 64500 to 67743, Ride 2: 71200 to 74443.5, Ride 3: 77900 to 81142.5, Ride 4: 84600 to 87843
Post-measurement cal - Ride 1: 96100 to 99343, Ride 2:02800 to 06042, Ride 3: 09500 to 12743, Ride 4: 16300 to 19543

Course Ride: Start: 93500 Finish: 34662.

a) Calculate the exact length in miles and yards

b) What adjustment would need to be made to the length to make the course exactly 25 km?

4. I measure a loop (of less than 8k) for a 50km race. The result for just one lap is counter reading at start of lap: 13000; Counter reading on return to starting point after riding one lap: 66476 counts. My constant for day is 9328 counts/km.

a) Calculate how many complete laps are required, and how much additional distance is needed to make 50 km.

b) How much is the additional distance in counts?

5. How long is a Half Marathon Race?

a) in metres

b) in miles and yards

6. The London Marathon Course this year had course changes from the East Parapet of Tower Bridge, through the Isle of Dogs and back to pick up the old course at the Traffic Light in Upper Thames Street, after Southwark bridge. Here is the Course Map which was prepared by Hugh Jones:

I rode the changed section in six rides. Some rides were in the direction of running, and some for traffic reasons where measured in reverse. At two points there were pedestrian railings which would be removed on race day, where I had to stop my measurement and resume on the other side. When this occurred I finished one ride with my front wheel touching the railings, and started the next ride with my back wheel touching the other side of the railings. I measured the length of my bike plus the thickness of the railings and found it to be 1.80m. Each the ride was less than 5 miles. My rides in the order I made them (not race order) gave the following counts at the exact reference points given:

95422 : Marsh Wall, Lamp Post M0142 outside Britannia Hotel
63770 : Front wheel touching ped. railing at the Highway

64668 : Back wheel touching ped. railing at the Highway
89664 : East parapet Tower Bridge

90300 : East Smithfield, west side of railing to crossing at Tower Bridge
06183 : Traffic Light in Upper Thames Street, after Southwark Bridge

22574 : East Smithfield, west side of railing to crossing at Tower Bridge
47831 : Direction sign S end Butcher Row

69196 : Marsh Wall, Lamp Post M0142 outside Britannia Hotel
89263 : Ride interrupted at white line to negotiate removal temporary road works obstruction ahead
90097 : Ride resumed at white line after removal of obstruction ahead
10596 : Front wheel touching ped. railings at West India Dock Road

11272 : Back wheel touching ped. railings at West India Dock Road
27754 : Direction sign S end Butcher Row

a) Using my calibration data given in Question 1.1 above, calculate the length of the new course of the London Marathon from the east parapet of Tower bridge to the traffic light in Upper Thames Street after Southwark Bridge.

b) Two IAAF measurers, and one US measurer measured with me. Our results were all within a span of 4.6m.
Calculate what this span is as a percentage of the distance we rode.

Go back to first page of introductory lesson with menu