Fitbit (Zip) and steps and calorie burn biking

[Heybales]

This comes up often it seems, how do I get steps from biking/spin class, and what about calorie burn?

Well, first off biking isn't steps at all, but if you just want it included as steps to reach goal or higher goal, go right ahead in your competition.

Putting on ankle will count 1/2 the steps if it even accurately sees each change in motion as a step.

Huh? 

When walking, the 3-axis accelerometer sense each foot step, not just the side it's on. On ankle, it's only going to see one, if even accurately.

Also, the calorie count based on your weight and stride length and impact seen tells if walking or running and what length of stride being used, that gives calorie count.

For the actual non-steps of biking, and only half of them seen at that - way off.

But here's my stats from a ride today with Zip on my side (not foot) - you can check it out on my profile, which has that stuff public.

What Fitbit saw for the time (210 min, actual ride time of 3:05 hrs, actual pedaling time (not coasting) 2:44).

Steps - 17604 (all but one 15-min block got VAM designation).

Distance - Don't know what it gave to just the ride, but 12.06 for just after the ride, a little walking around in morning, so maybe 10 miles. So it saw about 3 foot strides. (10 miles x 5280 ft / 17604 steps).

Calories - 1470

What actually happened, using my actual avg cadence of 89.9 during the 2:43:45 time of actual pedaling, and doubling for "steps" equivalent.

Steps - 29442 (89.9 x 2 x 163.75 min) (so if Fitbit seen steps was doubled, would have been 35208).

Distance - 56 miles (so even if Fitbit saw each "step" it would have only gotten to tad over 20 miles)

Calories - 3192 (so if Fitbit steps was doubled, it would have gotten 2940 calories perhaps, but then again with 1.5 foot strides it might have done the math differently and gotten who knows what).

So any way you look at it, even if Fitbit was to see each "step" of a biking foot going down, the math for calorie burn is going to be off.

Unless you already have a good idea of what your calorie burn is at different biking speeds/efforts, and happen to match the speed to whatever makes the Fitbit accurate - but if you knew that, why would you purposely go slower if you already had a good value?

So wear your Fitbit if you just must get steps even if they aren't really steps - but log your own calories.

[Colinm39]

@HeybalesI won't let you feel unwanted, I have linked your excellent post for another user.

I'm currently using my Fitbit to measure cadence on my stationary bike for my physio. He wants me do do a cadence of 80 for 5 minutes and increase it by 1 minute/day for my lower back issues. He even wants me to show a 5 minute video of front, back, and sides to ensure I'm doing it correctly. I have the seat height correct because my 48 year old son is a veteran cyclist and nothing passes his finicky eye.

[Heybales]

What!

Your son is a cyclist and hasn't dragged you out yet on a bike alot. You must have put up one good fight.

I'll be very curious to know if you seem to get good rotation figures doing 80 rpm.

Because I'm thinking any bumps must be giving me more steps than happen.

Because I did another 2 hr test today - with Zip on my ankle this time.

Fitbit saw 10564 "steps" of one foot x 2 = 21128 equivelent steps for 955 calories, or 1910 doubled like steps.

Actual was 88.7 avgRPM x 96 min of 2 hr ride = 8515 rotations or 17030 equivelent steps for 1976 calories.

Now that is actually pretty close. 3.3% error on calories after manual correction, or doubling of Fitbit's steps and calorie burn.

Longer test on prior post's data was 7.9% error after manual correction.

I'm not really sure how you'd confirm though if reported steps was right or not.

Got any songs with 80 bps you can pedal too? That's what I do on Spin bike during winter on my long personal sessions.

With computer you could use MixMeister BPM analyzer program on any MP3 songs to find the ones that fit the bill.

[Colinm39]

My son won't let me out. He has 9 road bikes. All types, super lightweight etc and rides about 80km per day. Does his weights etc. Extremely fit and regular rides in the 1 hour Vets.races.