Mounting the Sensor

Pete:
I am surprised that the fear of a dead battery is bothersome to you. I have many computers going back two or three years and have yet to see my first dead battery.
The BC600 you are using has a silver oxide battery while all current computers use a lithium battery, the life of which I suspect is appreciably longer.
Of course if you really want a back-up you can run two computers simultaneously and leave your Jones at home.
I am surprised that you have not upgraded to a Protege, which is a bit easier to operate.If you suspect that electronic measurement is in your future, I would urge you again to buy a Model 9 for $22 before they disappear.

Neville - I bought the model 9 today.

As for batteries, the BC 600 I am using came with an extra battery. When I started to use the unit, the battery crapped out in a few days, and I replaced it. It has continued to work OK, but the incident left me a bit gun-shy.

I retain some slight concern - when using four magnets, I can get a check at each stop to see whether any counts have been missed. I do not recall whether the one-magnet method has the ability to be checked periodically for missed counts. Ideally this should be caught in the postcal, but an enroute check would be nice.

Pete:
It is not necessary to check for occasional lost impulses with the Protege, because, except for the cases I mention below, they never occur.(All or no impulses are recorded.) One impulse is always lost in the following cases:

1. A ride of half a marathon without rezeroing.(Does not apply to the two-magnet method.)

2. The wheel is stopped for five minutes and is started again without first waking the computer.

3. Rezeroing is done with the wheel slightly ahead of the zero point. (Also does not apply to the two-magnet method.)

However, if many stops are made during measurement, it is possible through carelessness and bad luck to stop on the wheel zero point and roll back to generate one or two spurious impulses.(Using two computers simultaneously might detect these immediately.) Postcal is of no value in detecting these, but they are readily detected if at least one ride is made over the course with few or no stops.(Riding continuously between marking splits would be equivalent to the latter.)

I realize I stated something inaccurate in the last post. The Protege may APPEAR to miss impulses in two of the three cases above, but actually the only time it misses an impulse is when it is not wakened from a sleep before resuming measurement.

Neville – my comments on missed counts:

You said:
It is not necessary to check for occasional lost impulses with the Protege, because, except for the cases I mention below, they never occur.(All or no impulses are recorded.) One impulse is always lost in the following cases:

1. A ride of half a marathon without rezeroing.(Does not apply to the two-magnet method.) I stopped my bike when the count got to 9998, and gently rolled forward. Counting proceeded normally until 10,000 revolutions were recorded. Then the wheel rolled one revolution and a count was not recorded. On the next revolution counting resumed normally.

2. The wheel is stopped for five minutes and is started again without first waking the computer. I have noticed that if you do not “wake up” the counter a revolution will not be recorded the next time the magnet passes the sensor, thus will be “lost.”

3. Rezeroing is done with the wheel slightly ahead of the zero point. (Also does not apply to the two-magnet method.) When I rezero, I set the zero mark on the ground reference, then roll back a bit and rezero the counter. This arms the thing and subsequent operation – all the way to 9999 – is proper.

More comments:
I have found that the best way to learn about the Protégé 9.0 is to buy one and play with it. By rolling back and forth, and observing what happens, you will quickly learn how it works and gain confidence.

By the way – I originally had a Sigma Sport 600, with four magnets. It worked OK, but I did not like having to be alert about where I stopped, so as not to get a double-count if a magnet was close to the sensor. I bought a Protégé 9.0, set it at 9999, with one magnet.

Now I let the Protégé accumulate counts and use the Sigma Sport as a resettable counter for laying out splits. I record data only from the Protege. I never allow the Protégé to accumulate 9999 or more revolutions.

I like the electronic system and now use it.

A quick and dirty way to avoid the problem of a "lost" count on long rides:

When you get near 9999, keep an eye on the counter, Once it flips over to 0000, stop the bike, pick up the front wheel, manually rotate it 1 revolution. You should be back on track for another 9999 counts.

Pete:
The proper operating procedures you mention for avoiding the loss of impulses are all covered in my latest report on the Protégé (http://home.earthlink.net/~caverhall/protege/contents.htm). Also described in the report is the operation you failed to mention for avoiding a loss when the computer falls asleep during a halt in measurement. Before resumption, the computer should be awakened by pushing the body forward for one second.
You state that you rode for 10,000 rev without rezeroing and then found the display did not change for two revolutions. In fact you should have found this phenomenon not at 10,000 but at 9999. I hate to ask you to ride another 13 miles just to check this out!
You say you now use the Protégé. Does this mean that you have certified a course without the use of the Jones? I have done nearly forty such certifications so far but have yet to hear that anyone else has done even one.

Jim:
Note that providing measurements do not get in the way, your operation can be performed much more conveniently at any time before or after 9999. However, I think it is much easier to just add one to the counter reading at the beginning of the second revolution after first registering 9999. Alternatively you could subtract one at the end of your preride calculation of your goal.

Neville -

I measured a couple of courses with a JO counter mounted on the bike but using my BC600 4-magnet cyclocomputer for all the layout. When I stopped to take data it was Jones counts I recorded.

Then I acquired a Protege 9 and rigged it for one-magnet operation. I now use it in place of the JO counter. I use the BC600 as a resettable device for split layout and only record data from the Protege, which keeps an unbroken string of data.

I do not like measuring tricks that are unrecorded in the data, so I never permit the Protege to roll past 9999. I generally stop at, say, mile 10, take a count, and reset to zero again at that point. My string of data at this point might look like:

Mile 10 - 7547.23
Mile 10 - 0

I have measured a couple of courses electronically and have high confidence in the method.

Whether the Protege skips a count at 9999 or 10,000 may have been misobserved by me. Perhaps it was 9999 as you suggest. I will keep an eye open.

I have noticed that most of the people I've corresponded with who use the electronic method are using spoke counts. I believe they would profit from marking their rims in 20 equal segments, every 0.05 revolution. It is a boon to be able to get a direct decimal reading I've found. Marking the rim can easily be done in a half hour, and once done, it's done forever. Well worth the time.