Indoor biking (AKA, the art of going nowhere fast)

Seems pretty high based on what I think I know. I get suspicious any time a calorie burn is much over 10 cals per minute.

^^ My numbers are similar.

On average...
Garmin, via chest strap, gives me just under ~ 11 cals/min... Garmin via wrist hr gives me just over 12 cals/minute... Power-based gym bikes give me ~11 cals/min.

Of my three rides inside this week, the two 60 min rides were 480 and 504 calories and the 90 min ride (bleck) that I just finished was 782 calories. I train with power inside and thus trust those numbers. Strava, on the other hand, will inflate calories in every situation I've thrown at it both indoors and out (compared to data from Garmin (with and without power), Zwift, TrainerRoad).

Inside is actually far harder for me in terms of time spent in the saddle between it being warmer (which doesn't effect calories), never coasting, and not being able to get as physically comfortable in the saddle as I'd like/as I can get when I'm outside.

I'm more than willing to believe people can burn more than 10 calories a min on a bike (heck I personally know/have known plenty of people who can) but if you've just started riding that's exceedingly unrealistic.

Very much doubt 900/hr is right unless you are hiding a real talent for cycling with modesty.

That's about 250 watts of continuous high effort. I know someone who can cycle at that rate, he set a club record and got a podium place in a national 24 hr event (441 miles).

For a normal cyclist like me (5,000 miles last year, very good VO2 max) then my absolute maximum for an hour (FTP) is 213 watts or 767 cals. Remember that's maximal effort and not something I can do regularly.

186 watts for an hour is far more believable - 670 net calories using the regular 24% efficiency ratio (20% would indicate a pretty awful cycling technique!).
By the way part of the reason 24% is often assumed is that it simplifies the watts to cals conversion right down to Average Power in Watts per Hour x 3.6 = Kcals.

MFP outdoor cycling estimates are high (for road cycling) and can't be compared directly to speed indoors as it isn't really the same at all (wind resistance) and you are absolutely correct that the difference between 16 and 20mph is huge.

HR isn't great for calorie estimates without quite a bit of effort - have you had your max HR tested to set your zones? Have you had your VO2 max tested to calibrate/personalise your HRM?
HR is specially affected indoors when getting hot elevates your HR - it's part of the reason you see a drift upwards in HR while pedalling at the same speed/power.

Jthanmyfitnesspal wrote: »

I brought this up last year, but I still haven't figured it out.

MFP gives an estimate of 920kcals for an hour of "Bicycling, 16-20 mph, very fast," which is pretty close. (There is a world of difference between 16 and 20mph, in my opinion, so I look at this formula with distrust. Also, the resistance of the trainer isn't perfectly calibrated to outdoor cycling.)

Wahoo knows my weight, that I am male, my HR, and that I am indoor cycling. My HR is certainly in zone 4 and 5 the entire time. Riding at an average of 17.1mph gives 860kcals/hr on their app.

Looking back at some old posts from last year, I find a formula posted by @TheBigYin that gives the power formula for the Kurt Kinetic as

P = (5.244820) * S + (0.01968) * S^3
With S being Speed in Mph and P being Power in Watts

Plugging in 17mph gives an output power of 186 watts-- equivalent to 160kcal/hour. When I saw that formula last year, I didn't completely understand that you have to divide by an efficiency factor to determine how many calories you would burn in order to produce a particular output, and that that efficiency factor is somewhere between 20 and 25%, depending on the person. Using a 20% efficiency factor implies an 800kcal/hr burn-- that's comparable to the above estimates, although 20% is the lowest value (giving the highest burn rate).

So, maybe it's all true!

Just so many variables that it's hard to nail down. With a recent test showing that even many power meters were less accurate than many thought, topped with drivetrain losses, and the efficiency factor.... in the end nailing down calories for any single person gets tricky.

Just efficiency alone is represented in the below. I really wish they had charted more realistic ranges. IIRC the numbers showing averages in human population are closer to the 19%-27% range.




In the end, the best most of us can hope for is a repeatable margin of error, and thus the overall trend shows us making progress (or not) towards our goals. With weight and aero drag being of huge consequence on a bike, nothing short of accurate calibrated meters and/or a rolling weather station that interfaces with a properly designed app will give really great results. Even with meters, the efficiency is a big guess.

All that said, I think my highest wattage numbers were when I was still on the heavier side, but had really upped my VO2max and LT due to a decent bit of riding.

megs_1985 wrote: »

I’m just getting started in biking and we got an indoor trainer recently. I was debating the Wahoo sensors because when I did spin in the past I liked trying to beat my numbers. Will the Wahoo sensors and Strava or Zwift give me calories without a fitness tracker? (I don’t have Garmin). I want to join a cycling club this spring so wondering what would be beneficial. Some of this info is going over my head I admit but all very informative.

In terms of speed sensors, unless your phone has ANT+ sensors (some do - including a good chunk of the Samsung Galaxy series) you'll want a speed sensor that can broadcast over Bluetooth. Getting one that can do Bluetooth and ANT+ is likely a good idea if only because if down the line you decide you want a bike computer and the one you want doesn't support bluetooth you'll be covered. There are also ANT+ dongles for phones and computers but I'm assuming you don't have one.

That said, anything that transmits bluetooth would work which gives you a fair amount of options. I personally use the Wahoo speed and cadence sensors that rely on acceleromters as opposed to magnets becuase I was very tired of dealing with "Oh is the magnet too far away? The sensor got moved so now I have to adjust it, but it can't be too close because otherwise it will just physically hit the magnet." The speed sensor goes around the hub of either of your wheels - if you're wanting to gather speed data inside on a trainer you'd put it on your rear wheel.

Regarding Zwift and Strava. If you want to use Zwift (or any other virtual cycling software) and you don't have a smart trainer you need a speed sensor. There's no way around that. In terms of Strava from what I understand, you don't need one if you're riding outside.

My bike says I burn over 1000 calories in 2h of biking but according to my apple watch I only burn 350 LOL.