Bontrager Cycle Computer - Calories Burned

mjbnj0001

Hi, all. I've just received a Bontrager Trip 100 Cycle Computer for my birthday. It's probably not the unit I would have chosen for myself, but of course I'll use it (I will also continue using "Ride With GPS" on my smartphone).

Question: it provides an estimate on "calories burned." I presume this will be a general computation, perhaps not entirely accurate, and maybe useful. My question - it requires "weight" to be input. I guess this is "my weight + bike + kit total" (or approximation). (??) The user manual doesn't say.

heybales

I'd suggest the whole weight - because any calcs would need total weight being moved.

Problem is it doesn't know rolling resistance of your tires (it's using an avg), doesn't know air resistance of your position and wind, doesn't know inclines/declines.

While it could assume a head wind will be balanced out by tail wind - that never works out.
Nor that down will balance out up a hill - that never works out.

So it's going to be rough - but can get in the ball-park.

This calculator can show you how extreme it may be - if riding slow enough some of those things won't matter much on short trips.
This shows all the variables, which you'll notice a bike computer won't know most of them.

http://bikecalculator.com/

sijomial

I would also guess the weight is total weight of you and the bike ready to ride.
Strava separates the bike and rider weights.

Does the Bontrager know what type of bike you ride?
Does it have GPS to know the terrain you are riding on?
If not then you might as well totally ignore the calories it displays, my extremes of cycling include off road on sand on a MTB and a fast road bike which highlights the problem of basing calorie estimates on speed and distance.

Are you linking a HRM to it? Then you would have at least something to guesstimate calories (with all the limitations of using HR....).

mjbnj0001

Thanks, both! I suspected total weight. And only middlin' accuracy from the device, LOL.

The Bontrager is a simple cycle computer as a birthday present. Doesn't know terrain, etc., or really anything other than the basic setup params.

I've been mostly using "Ride With GPS" ("RWG") on my Android phone (over both Strava and "Map My Ride" and a couple of others I trialed earlier this year). It provides for "gear used" in a ride in addition to user profile bodyweight to compute approximate power and calories burned; according to their site "... the numbers produced are not perfect – however, they are accurate enough to be useful."

It will be interesting how the two computations compare over time. I like a cycle computer for simple display of time, speed, distance and will let the smartphone continue logging the more comprehensive track info sitting in its pocket on my small handlebar bag.

We also sail, and I already have a bag full of GPS units (marine-oriented) and wasn't too enthused about buying another this year for cycling. Technically, I __could__ use them to track my rides, but their chartplotter presentations wouldn't depict the roads/trails. I already export the data from RWG to a GPX viewer for nicer presentations than the RWG website and therefore might get good map tracks in a post-ride analysis mode.

I've sort of laid out my return-to-cycling-after-30-yrs story here on MFP a couple of times, don't want to repeat it, LOL. I've been frugal in making additional expenses after the bike itself while this activity has been proving out as something that I could do (it wasn't entirely assured when I started). Now, at 400+ miles for the year so far, I can say I'm off and running. Er, cycling. The next round of larger investments for goodies will probably be Christmas, and electronics are front-and-center.

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HRMs -- I have some cardiac issues (and the riding is helping). Most HRMs aren't accurate with my rhythm. When I go to the gym, I'm using a pulse-ox fingertip HRM - makes me feel as if I'm a real dinosaur compared to some of the things that others are using. But a couple of my docs use the same model, so I go with consistency. I literally just got back from one doc's 3-mo followup appt, and had asked this morning if they support these things or even something like Kardia Mobile. Nope. Both tech and nontech barriers to adoption. I stopped carrying the pulse-ox on the bike when I ride when it became apparent I wasn't going to keel over every ride, LOL. But I still toss it into my "sag bag" when I rack up the bike and drive to a trail somewhere. I also keep an HRM app on the Android phone which is also running RWG.