cyclometers

Does anyone have an idea about how accurate cyclometers are w/ regards to how many calories they say you have burned?

 

If they don't ask for your specifics like weight, height and vo2 max, they won't be very accurate. I think the accurate ones are by Polar unless they ask for specifics. Other than that they're just general estimates I think.

 

that's a bit frustrating subject, i have seen too big a difference to rely on any burnt calories readings.

 

My rides this weekend include a 10 mile (first ever on my new road bike), a 20 mile and another 20 mile.

5'10"
149 lbs
VO2max = 50
Maximum Heart Rate (MHR) is 180bpm

The 10 mile ride lasted 42 minutes, my average HR was 156 and my MHR was 171 bpm, I burnt 547 calroies

The first of two 20 mile rides lasted 1 hour and 25 minutes, my average HR was 153 and my MHR was 173, I burnt 1063 calories.

The 2nd 20 mile ride lasted 1 hour 23 minutes, my average HR was 146 and my MHR was 179, I burnt 954 calories

I'd say those are pretty reasonable numbers.

I'm using a polar ft 40 watch for heart rate and a cateye v3 for distance and cadence.

 

Yes but you are using the same Polar unit.
From my experience, with a different Heart Rate monitor, even from the same brand, the calories numbers vary a lot for the same effort.
Then you go to the gym and you get again different readings on the treadmill for example. And so on...

 

This has been discussed at length a number of times. Tried finding the most recent thread but to no avail.
Always keep in mind that "accurate" is a relative term.
Cyclometers/calorie counters are not accurate compared to a lab test (exhaled gas analysis) where it gives you fat and carb grams burned at particular wattages (much better metric for intensity than HR).
Cyclometers/calorie counters are more accurate than most, if not all, on-line calculators.
Knowing your own particular gross mechanical efficiency is critical to computing energy expenditure numbers. Cyclometers can't possible have this info on each individual - they use some default number for a given set of user input variables (i.e. age, weight, sex, etc).
Best to compare apples with apples, or compare your own cyclometer's burned calorie numbers to itself and not cross measure with other methods.