Conference noted::bicycle

>    Could anyone give me the Cateye settings for a 27X700C.

	Does that 27 mean 27" (as in 27x1.125) or does it mean 27mm
	as in 700C x 27mm?

	If you want your CatEye to measure kilometers and kph, the 
	setting is the circumference of the tire (NOT THE DIAMETER!) 
	in milimeters (millionth's of a km).

	If you want your CatEye to measure miles and mph, the setting
	is the circumference of the tire in millionths of a mile.
	You can measure in inches and multiply by 15.782828 to convert
	to millionths of a mile. 

	In either case you can approximate the circumference by
	multiplying the diameter by Pi (3.14159 will do). Remember
	that a 700C tire is not 700cm (or even 700mm) in diameter.
	(27" * Pi * conversion = 1339)

	The best method is to put a drop of paint on the tire and
	ride forward on a smooth surface.  Measure the distance
	between paint spots to get the REAL circumference.

    Thanks,
    
    Now that the brain is jogged, I remember the 1339 number as it.
    Might still try the paint trick just for fun. (not to mention the
    accuracy).
    
    dave

    Start with 1339, but then cover some distance that you are confident
    that you know the actual milage, the  adjust.
    
    If you know, for example, that the distance from home to work is
    15 miles (as measured in a car, or several cars) and you ride it
    and the Cateye says 15.3 miles then you know how much you need to
    adjust the 1339 setting.
    
    If you do the rolling example, then make sure you do it on a hard
    surface with you sitting on the bike and with the proper tire pressure.
    
    I use 1325 and feel it's pretty accurate.
    
    Bob
    

Automobile odometers are seldom as accurate as a CATEYE (once it's
adjusted).  Cars are often off by 10%.

    re .4 Right, that's why I said several cars.  If both cars I own
    clock a roughly 15 mile route within .05 mi then you can be pretty
    sure it's right.
    
    A cateye isn't inherently more accurate than a car odometer, they
    both count wheel revolutions.

    
    I'd have to think that a cateye is more accurate than a car.  Yes
    they both do count revoloutions, but with the cateye you can 
    "calibrate" it to your bike with your tires at a particular pressure.
    The car speedo has been calibrated X years ago in a factory using
    possibly different tires at a different pressure. Also the tread
    wear on the tires is probably a substantial factor as well. Are
    the tires the same size as those originally on the car?  I'm sure
    we could up with a couple of other variables as well.  
    
    I think cateye advertises a 99.9% accuracy or something like that
    when you calibrate it the right way....
    
    Stew
    

    re  the last few.  Car odo's can be accurate to within 1/10 of a
    percent too;  HOWEVER, as has been pointed out:
    a)	The drive gear needs to be exactly right for the axle ratio
    and tire combination, I think there are typically a couple of dozen
    different plastic speedo drive gears for each transmission.
    b)	Tire wear needs to be 'negligible', i.e. less than 1/10 of a
    percent in rolling circumference if that's what you're expecting
    from your measurement.  I would guess that some nominal wear is
    allowed for in the arithmetic, probably 10 or 15 thousand, EMPHASIS
    I said "GUESS".
    c)	Tire pressure needs to be set correctly cold, and the tires
    need to warm to normal running temperature.

    	You can get a good calibration of a car's odo by measuring mile
    markers on an interstate.  Set your tire pressures cold, as above,
    drive at highway speed (whatever that is to you) for at least 20
    miles, check at least three markers before sync'ing up on them to
    avoid getting one that's placed wrong due to a bridge, intersection,
    or whatever, then measure over a 10 mile distance, every 1/10 that
    your odo is off represents 1 %, etc.  If you're going to use this
    to calibrate a Cateye then make the measured run under the same
    conditions, preferrably as soon as you get off the highway and can
    set up a measured 10 or 20 mile bike ride, this will leave the minimum
    opportunity for params to change.

    	Having said all that I believe that it really doesn't matter
    that much.  How far I ride is only significant when compared to how
    far I rode the previous week, month, year, whatever, i.e. its only
    a relative measure, extreme accuracy doesn't matter THAT MUCH, to ME.

    	Reg
    

     Having started all this, I must admit my point of view is closer
    to Reg's.  I simply want some idea of how far I went relative to
    last time.  I went with 1339 and it seems quite reasonable.
    
    Thanks for all the help.  I do appreciate it
    
    Dave

	How's this for accuracy:

	A 27" wheel turns about 750 revolutions per mile.  The Cateye
	can be calibrated to the nearest 1/1,000,000th of a mile.  The
	maximum error per revolution would be 1/2,000,000th of a mile
	and therefore the Cateye can be calibrated to an error rate of
	.0375% (about 2 feet per mile).

    
    re .9	Gee, I didn't know that anyone over the age of 12 rode
    		on 27 inch wheels.
    
    	Lessee, a millionth of a mile would be, Ummmm, well a mile is
    1760 yards, or 5280 feet, or 63,360 inches;  a millionth is gonna
    be about 1 1/2 tenths of an inch, OK "150 thou" if thats how you think.
    Seems this only gets to be meaningful if you are able to measure
    the rolling circumference of your wheel to within;  Ummmm<long pause>
    0.150/750 inches, or 0.0002"  Well, good luck with that one !
	I'd rather stick with the long distance calibration ride and
    reduce the error by division;  course, I'd really rather ride than
    do this nonsense, anyone else commuting by bike THIS week ?
    
    	Reg
    
    
    
	{Does anyone over the age of 12 write programs in BASIC ?}
    

    I once had one of those things (it was a "Push") but it died in the rain
    and I tossed it...  but it was kind of nice for gauging my performance so
    I might get another one if a really small one that's reliable exists.

    Once I stayed in gear and counted pedal strokes on a measured mile
    to test my wheel diameter.  (It actually took me two tries to do it
    since the first time I rode past the mile I lost count due to boredom
    and had to retry on the way back!)

    So much for TSD techno-dweebing...  (great phrase that: one that really
    ought to be better known to certain inhabitants of the AUDIO notes file.)

    - Jim

	Here are some official numbers (I found my owner's manual):


	magic   wheel diameter
         no
	1308	26.4 (700 x 25C)
	1327	26.8 (700 x 28C)
	1339	27.0 (700 x 32C)

    
    	I had the back wheel off of my ATB once and shoved a 700 wheel
    in there just to keep it up off the ground (no, I wasn't in my fully
    equiped fancy "workshop").  As a matter of curiosity I wondered
    how different the rolling circumferences actually were.  I took
    it down the driveway and when I got to the road I set both wheels
    so that the valves were each at the 6 o'clock position and then
    started walking the bike in a straight line.  I was expecting/hoping
    that by fifty or so revolutions one wheel would have gone around
    exactly one time more than the other, then I'd have a n/(n+1)
    correction factor, (n+1)/n if you wish.  It seemed I was in for a
    pretty long walk, so I gave up and decided that I could just use
    the 700 setting on the ATB wheels, "close enough".

    	R
    

	There's a new computer on the market; I haven't seen it in any biking
    magazine or mail order catalog:
    
    Cateye Vectra	- 38 grams, total weight
    			- Curr speed, max speed, avg speed, elapsed time,
       $ 39.95		  total distance, & trip distance
                        - battery lasts 2-3 years
    			- waterproof
    			- 2 3/16 x 1 13/16 x 27/32 dimensions
    			- attatches easily to front fork/wheel
    
    I found it in Frank's Spoke & Wheel, Framingham, MA on Rt. 9. (872-8590)
    It's also in Frank's other 4 stores (Westboro, Waltham, Natick,
    Sudbury).
    
    Mark

    I also saw this in a bike shop.  It is basically the same as a cateye
    micro without cadance.  Front wheel mount.  Same price.
    
    /Jim Pappas

    I joined the computer age at the weekend and bought a Cateye
    something-7000. I think it may be the same model as mentioned in .14,
    except that it's handlebar-mounted. It measures total mileage (or
    kilometreage) ever (currently 14.6 - wow), trip mileage, and current,
    top and average speed. Best of all, I've been able to install it in
    that flash way where the sensor wire spirals self-importantly up the
    front brake cable - love it.
    
    And I've found that computers are the cyclist's equivalent of in-car
    telephones. They open up whole new vistas of crash-causing
    distractions! I'll just ignore that looming artic while I find out the
    current trip mileage...
    
    I nearly got a Vetta model which added a clock to the Cateye functions,
    but being a practical, scientific sort, I chose the Cateye anyway
    because it looked better. Price was �29.95.
    
    
    Rod

    
    I am not sure where to put this, so I'll try here.
    
    I have a Cateye Micro I picked up a couple years ago.  I have used
    the basics for some time, but have picked up cycling lately and want
    to use more features.  Unfortunately, I have moved since the last time
    I refered to the manual and it is now lost in the morass that is my
    basement.
    
    Soooo, I am hoping to find someone who has a manual that I could copy.
    I am in the Pan Mass Challenge this weekend, and was hoping to use it
    better for the race, so someone in the greater Nashua/MKO area would
    be ideal.
    
    I can be reached at KAHALA::SURDAN or dtn 264-4584
    
    Thanks for the help!!!
    
    Ken
    

    
    Well, that network can be really fast.  I already have two offers
    to help, so I should be all set.
    
    Thanks!
    
    Ken
    

A friend of mine just bought a bike with a CATEYE VECTRA  cc-7000 computer. He
Doesn't have the manual for the computer. Can anyone give me directions on how
to calibrate this thing? Don't know what kind of tires he has so a few magic
numbers would help. Thanx.

I just did this over the weekend - it goes something like this:

1. Measure the circumference of the tire in centimeters.  (A 700Cx20 is
about 209 cm)

2. Put the computer in ODO mode, stopped (press the start/stop switch
on the right until the display doesn't flash, then press the mode switch
on the left until the display says ODO).

3. Press the mode switch simultaneously with the AC button (small button on
the back).  A three-digit number appears and flashes.

4. Press the start/stop switch until the three-digit number matches the
measured tire circumference.  (The numbers increase to the top of the range
and then wrap around to the bottom.)

5. Press the mode switch again to return to normal operation.

This assumes that my memory is correct and that your friend has the same
"Cateye Vectra" as I.  I'll try to remember to bring in the manual tomorrow
in case this doesn't work.