Incorrect measurements on my Polar HRM

[Bub Marley]

I've noticed that my Polar CS300 has been giving me incorrect distance readings. Yesterday, I did the 85km West Coast Race and it told me I did 79km. That's about 6km out. I've checked all my settings and it all corresponds to what's in the manual. I ride a 700X23 wheel and I've punched in the correct measurements which correspond to that.

 

Am I missing something or are these things not reall that accurate?

[SwissVan]

Rather measure the actual wheel diameter and use that as the wheel setting, the manual default one's cannot be accurate for all the different types of wheels and tyres out there

 

< Find a straight line on the ground long enough for one complete revolution of your wheel

< Mark a start line (thin line) on the ground line

< Draw a thin line on your wheel side wall.

< LIne the 2 lines up.

< Roll (preferably while you are on the bike) the wheel as straight as possible until the mark on your side wall has done 1 full revolution, mark the spot on the ground line.

< Measure and enter manually into the computer.

 

 

Also the race distance, LOL never believe what they advertise

Edited October 14, 2013 by SwissVan

[rouxtjie]

I've noticed that my Polar CS300 has been giving me incorrect distance readings. Yesterday, I did the 85km West Coast Race and it told me I did 79km. That's about 6km out. I've checked all my settings and it all corresponds to what's in the manual. I ride a 700X23 wheel and I've punched in the correct measurements which correspond to that.

 

Am I missing something or are these things not reall that accurate?

It might be that the race distance wasn't accurate, follow swiss's advice, measure it and input into computer, it should be more accurate than gps distance

[Bub Marley]

I'll try that out. Thanks, guys.

[90 Inch]

I got 82Km for the WCE on a Garmin (GPS Only), so 79Km is only 4% under, look up the factor you have for your wheel sise and reduce it by 4%

[Bobbo_SA]

What i do is put a small "puddle" of water down on the driveway, ride over it in a straight line for 4-5 turns of the wheel, then get off and mark each wet spot with some chalk, meassure the total between the start (you can use the first spot as the start and not the puddle if you like) and end, then divide the total distance by however many revolutions you got (before you rode into the wall / gate while starring at your front wheel)

 

Edit: S&G

Edited October 15, 2013 by Bobbo_SA