Average Heart Rate - is it a useful performance comparison?

[Bolt]

The reason I ask is that I'm looking to sustain/improve my average audax speed as I near my 60s.  I have previously favoured relatively heavy bikes with wide tyres (hardtail mtb) in the interests of comfort and practicality but over the last year or so I have been experimenting with more conventional lightweight road bike and wheel configurations.  Although these set-ups feel much faster and easier, my ride data is telling me otherwise!?  Over the last few months I've been going out for recreational rides between 60km and 80km with an elevation gain averaging around 600m and alternating between the road bike and mountain bike.  Though the rides do seem slightly harder work on my mtb the ride data is consistently indicating that the mtb returns a slightly faster average speed, a slightly lower average heart rate and a significantly faster downhill speed.  The mtb's tyres are 20mm wider and the stock mtb wheelset cw tyres around 800g heavier than the Mason Hunt 4 Seasons tubeless hoops on the road bike. 
So, could I be using more energy on the mtb than the hrm data indicates?  My average speeds range between 20-25kph so I'm guessing the aero advantage of the road bike is also less of an advantage?

[grams]

Speed on any bike at any speed (outside long hill climbs) is primarily about power output vs aero drag, and in particular aero drag of the human on top. How do your positions compare? Which bike are you more upright on in your normal riding position?

Descending speed has a very large confidence component, which an MTB with good brakes and chunky tyres can add a lot of. Are you happy descending on the road bike? Are you confident about brakes, cornering, grip, etc? Are you using the drops and getting low?

[quixoticgeek]

Different bike positions use different muscle groups too. So while a road bike and a mtb are both bikes, you may find that you are stronger on one than the other, purely from the position you are sat in.

I find this with having spent so much time training on the aero bars, that my strongest muscles are in the aero position. Which has the downside of looking like a complete idiot climbing up a hill at 7kph in a tt pose...

How does your body position compare across the 2 bikes?

J

[Bolt]

My position on the road bike is significantly more aero than on the mtb and I'm using the drops at least 50% of the time.  With the exception of descending, everything "feels" faster and easier on the road bike, I'm just really puzzled why this perception isn't backed up by the ride data.  J raises an interesting point about different muscle groups being at work, though most of my riding last year was done on a road bike.  I do think that my average speed of 20-25kph has become "programmed" into my riding style and that regardless of the bike I will unconsciously adjust my effort to maintain this, which is why I became curious about measuring heart rate fully expecting to see a lower average result with the "faster" bike.

[PaulF]

Can you compare the same ride on both bikes in something like Strava? Strava would allow you to view a "virtual race" between the mtb and road bikes to see where you're faster. You could also compare segments.

That way you should be able to see where the gains are made.

[simonp]

A more aero position can lose you power. In TrainerRoad you’re encouraged to try to find a balance between aero efficiency and power. The most aggressive aero position isn’t necessarily the fastest. Going onto the drops might be enough when you’re not used to it to lose some efficiency. Particularly with the change in hip angle. Maybe experiment with riding on the hoods and see if your heart rate is lower.

[Peter]

Do you log the weather conditions?

[Phil W]

Average speed is all about time. It’s distance divided by time. So if your average speed on the road bike is slower than mtn bike, you are losing more time on the road bike than you are gaining.  So as has been suggested you could use Strava to directly compare the same route ridden on the road bike and mtn bike. You can select the segment leader boards to show just your own rides . Then look at dates for mtn bike and road bike on different segments to see where you are taking longer on the road bike and by how much.

Another thought. Is the road bike encouraging you to push hard on the uphills, pushing the HR right up, and so you are coasting more downhill to recover. On the mtn bike you automatically gear down, don’t push as hard uphill but only lose seconds, then really pedal the downhills and gain more than you lost?

[Kim]

FWIW, I find that my flat-out hill-climbing performance is usually best on whatever I've been riding the most.  And that's with geometries a lot more different than road bike vs mountain bike.

I also find that there's a strong psychological factor to speed, both in terms of how fast you can descend without feeling like you're straddling the line between control and imminent splatty DETH, and in terms of what feels like a reasonable cruising pace.

And finally there's the performance of the bike itself.

[DuncanM]

Wind, cold, wet roads, position, clothing, comfort - all can affect the power required to maintain the same speed.
Hydration, sleep, caffeine, illness, position, comfort, effort - all can affect the HR needed to maintain the same power.

If you did the same route, on consecutive days, with similar clothing and weather conditions, you might be able to remove a large number of confounding variables, but if you want to know if the road bike is faster for the same power, you need a power meter (ideal pedal based so you could switch the same power meter across bikes).

One potential reason for your HR being the same on the road bike could be that your upper body/core is working harder to maintain position, while your legs are working less hard. I think we need more data!

[FifeingEejit]

Descending speed has a very large confidence component, which an MTB with good brakes and chunky tyres can add a lot of. Are you happy descending on the road bike? Are you confident about brakes, cornering, grip, etc? Are you using the drops and getting low?

Aye, my best descent off the Cairnwell pass into Braemar is on a full sus with 26x2.35" knoblies, 203mm/180mm rotors and 4-pot brakes.
The upright position on that didn't feel as fast as being on the drops or hoods which helped in the corners.

[zigzag]

for me something doesn't add up here. unless your mtb is top notch and optimised for speed, and road bike is really really bad - road bike should be faster by a few kph.

[DuncanM]

I assume you're using the GPS speed and distance data? If you are using a speed sensor, maybe it's got the wrong wheel size?

[Bolt]

for me something doesn't add up here. unless your mtb is top notch and optimised for speed, and road bike is really really bad - road bike should be faster by a few kph.

So, I've pulled a bit more data out of Strava looking at rides over 70km over a 2 year period.  During 2017 I was riding the BTwin Rockrider mtb for recreational rides and audax including LEL, completing a total of 5365km with an overall average speed of 20.1 kph.

At the beginning of last year I started riding a lightweight steel Ellis Briggs road touring bike and rode 2059km with a reduced overall average of 19.6 kph.

At the end of last year I began riding the GT Carbon road/gravel bike with Hunt 4 Seasons wheels and G-One tubeless.  I've completed 985km with an overall average of 21.8 kph though this does not include the same amount of off roading that I do on the mtb.

All speed data is derived from GPS.

[LMT]

Six of one and half a dozen of the other.

Post the files for each ride showing speed and hr.

[Bolt]

I've only just started measuring heart rate on shorter rides hence my original post, until then I always assumed that I just regulated my speed to be a constant irrespective of the bike and was expending more effort on the mtb.

I don't tend to ride the same courses often but here's a couple of rides done on the subject bikes:

Kennet Valley 200 on Road Bike https://www.strava.com/activities/1446113931/edit
Kennet Valley 200 on mtb https://www.strava.com/activities/896266541

[zigzag]

still too many variables, e.g. mtb ride done in good weather with more people in a group, road ride was on flooded roads and snow with one other rider. g-one tyres aren't exactly built for speed, more of an all-rounder mixed surface tyre.

i would try to eliminate as many variables as possible and do a 2-3hr loop several times on different bikes to arrive to any meaningful conclusion.

[grams]

Average speed on Strava is subject to what it decides were your stops, as well as whether or not you include the ride to/from the event, and so on.

I note no one has commented on the question in the title - does anyone have any comment on whether HR data is a good proxy for power data?

[toontra]

I note no one has commented on the question in the title - does anyone have any comment on whether HR data is a good proxy for power data?

Indeed.  That's why I'm here 

[Greenbank]

I note no one has commented on the question in the title - does anyone have any comment on whether HR data is a good proxy for power data?

I'd go for "no, it isn't."

Have a look at the data from my spin class this morning:- https://connect.garmin.com/modern/activity/4406012159

Expand the power graph and overlay HR on it, you'll see that HR lags behind power increases/decreases by at least a minute (the rate at which you adapt and recover is a far better measure of "fitness"). It's also nigh on impossible to correlate the two.

There's also inconsistencies based on not being fully up and running, the first minute long interval at ~350W had a HR lower than the subsequent minute at ~300W.

For the 20s "sprints" at 120rpm it doesn't spike like the power does compared to the 40s "rests" at 80rpm (same resistance).

For longer term comparisons, like using average HR from the entire ride/run, I've had rides/runs where I've felt just as I did before (I tend to do the same training loops over and over again) and took pretty much the same time but HR_avg can differ by anything up to 10bpm up or down. This could be fatigue, weather, illness (coming on, during or recovering from), a rubbing brake pad, etc. It's just too inconsistent to draw any meaningful data.

For running I use "beats per mile" (after reading something by Steve Way, not this specific article but it'll do: https://www.33fuel.com/news/heartbeats-per-mile-a-better-fitness-measure-than-heart-rate/ ) as a reasonable gauge of fitness, but that assumes a mostly flat run, or at least only compared on runs on the same route. I also squint when looking at the results.

You might be able to do the same thing for cycling. I have a power meter so I don't need to do that for cycling.

[zigzag]

I note no one has commented on the question in the title - does anyone have any comment on whether HR data is a good proxy for power data?

Indeed.  That's why I'm here 

it's been talked about time and time again, it's better than nothing and works well alongside power data, but the hr data is too variable and inconsistent on it's own.

[perpetual dan]

I note no one has commented on the question in the title - does anyone have any comment on whether HR data is a good proxy for power data?

Without the benefit of citations, i think its a bit approximate.

Doing intervals, on a turbo, with control of resistance and direct comparison with previous sessions i reckon HR gives a similarly useful measure of effort.

On a ride, HR is a bit laggy and affected by things like recovery and cumulative effort. I'm not sure I'd put a lot of value on data from one strava segment without looking at the surrounding time periods.

That said, i reckon either is a viable way of pushing or pacing oneself, with the benefit of knowing percieved effort, the weather, what bastard hill is coming next etc. Different, but viable.


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[mattc]

HR data is very useful. To say otherwise would be saying that before power meters, noone could do structured training! (and what about runners??)

But it doesn't tell you what power you're putting out. If you kept ALL other variables the same, then yeah, Avg-HR probably correlates quite well with your "training/fitness level". If that's what you want: 
I don't really care about measuring my fitness, it is what it is - the process is much more interesting - but others are obsessive about monitoring/measuring!

[toontra]

Today on a 60 minute continuous steady effort on the trainer my HR was significantly higher against wattage output than usual.  I put this down to being on the tail end of a bad cold.

So yes, I find it useful.  Going by wattage alone I could have assumed I wasn't putting enough effort in.

[DuncanM]

HR is useful. You can do all sorts of things with it, from looking at resting heart rate and the HRV stuff to see when you are getting sick or recovered/not recovered prior to working out, to using zones to hold your effort levels during a ride, to post ride analysis like comparing variability over long intervals to see how your baseline is changing.

However, using HR alongside speed for comparing different bikes across different seasons? Too many variables. Maybe you were fitter 2 years ago? Or lighter? Maybe the summer 2 years ago was nicer than the one this year. Maybe you were active doing other things, or more stressed? Maybe you have changed where or how you ride? I had routes that were much faster in one direction than the other (long sweeping smooth corners one side of the hill, and sharp corners with limited visibility and a bad surface on the steeper side), or were much faster on one bike compared to the other (super steep stuff both sides were better on the MTB because you could climb in a better gear, and you could go faster downhill because you knew you could stop).
If you are going to compare rides one against another, ideally within a few days, then maybe you can use it as a proxy for how hard you are trying, but I don't think it works on an aggregate basis.