I do several hours a week on utility rides on bikes without power meters on them. Is there a low effort (ideally automated) way to estimate the training load of these rides?
What I do now is find a ride of comparable intensity and then use the two durations to calculate what fraction of load and then manually edit the load figure. But this is quite tedious so I don’t tend to bother unless I do a particularly long ride.
As I read this back to myself, the obvious solution is for me to assign some intensity factors based on historical rides and write myself a calculator/crib sheet. But maybe there’s a way that I’m missing?
My main use for the load is to ensure the fitness graph will warn me if I am at risk of overtraining.
You can use HR from a watch or a HR strap, you can even put your wahoo or garmin into a pocket if you can`t mount it on the bike.
ps. Fitness graph is to plan into the future not to warn you. I mean first you look how do you feel and eventualy compare it with your fitness graph not the other way around
Thanks. I don’t own a heart rate monitor. I’ll think about getting one.
As for the fitness graph, I have small kids, so I feel tired all the time anyway The graph helps me diagnose the cause. I do use it to plan a couple of weeks ahead.
Thanks. If I switch to HR and TRIMP / other strain based load estimation, I am assuming it makes sense to use that for all rides, including the ones with power data. I skimmed the thread and it seems there was a bit of back and forth about whether the two were strongly enough correlated.
In settings, make sure your order of Load Priority is Power, HR, Pace, then your rides/workouts with power will be calculated first, and if no power meter, then HR and finally pace.
I have fairly accurate load data from my HR only workouts (MTB), which I also estimate based on past efforts, or knowing that a certain average HR (constant efforts) will yield a range of load within about 5-8% of the effort with a power meter.
Looking for this too… I am trying to retrospectively analyze my hundreds of activities from 2016-2018 (bc I was much faster then!) and none of my rides have a power meter and most do not have heart rate. I know the strava power estimates aren’t great but they’re better than nothing. And now that I’ve been using power for a while, I think they are fairly decent estimates. Was hoping intervals.icu could calculate something similar since strava doesn’t seem to export the estimated power.
Any thoughts on this or what you would do to analyze old rides with no power, no heart rate? I have speed, distance, moving + elapsed time, elevation… I have thought about going through and retrospectively assigning an RPE although that would take me many hours and of course be fairly inaccurate.
What I want to do is compare my training now to my training then and also get a feel for how my intensity distribution looked then.
Estimating power from speed and gradient etc. isn’t something I have looked into. The problem is of course wind which has a huge effect.
If you just want to estimate load maybe you could do that from average speed, distance and total elevation gain for each ride. You can get that data from the CSV download on the calendar page (Options → CSV). You could use your rides with power (and hence load) to get coefficients for those and then calculate load for the old rides.
I’ve opted to do a side-by-side strava and intervals.icu evaluation and am assigning an RPE to all of my old rides using a combination of the strava power estimates, strava PRs, ride descriptions, and general recollection of what the rides might have been like. Not great but will get me close enough. Just time consuming!
kilojoules
float The total work done in kilojoules during this activity. Rides only average_watts
float Average power output in watts during this activity. Rides only device_watts
boolean Whether the watts are from a power meter, false if estimated max_watts
integer Rides with power meter data only weighted_average_watts
integer Similar to Normalized Power. Rides with power meter data only
The Power Estimation Curve is available for Strava subscribers.
First Principles, real-time power could be estimated with:
total mass = bike + rider + gear
grade % (or slope in degrees)
pedal rpm
coefficient of drag, wind resistance
rolling resistance
GPS 1 second data
wheel speed
Grade can be approximated with Elevation change. Elevation may be estimated with GPS and USGS TOPO maps. GPS and wheel speed can give us velocity. First derivative of velocity is acceleration. Acceleration of vertical component * mass. If theta is the angle of grade, where 0 is flat, then sin(theta) * mass * gravity is the vertical component.
Wind resistance scales with v^2 * C_drag. Also includes rolling resistance, a function of velocity.
Net Force Balance Equation
F_rider - F_drag - F_slope = 0
F_rider = rider_torque * system_efficiency
F_drag = F_wind + F_roll_resistance
F_slope = mass_total * sin (slope_theta)
Some logic will be necessary as well for the crank rpm data. Spinning, Coasting, Spinning Reverse.
