Estimating trainer 'effort above the flat' by heart rate + cadence

A question popped into my head after yesterday's trainer ride.

First, a long-winded preamble.

As I pointed out in this question, I usually set the trainer up so that a 5l cask of wine just moves the pedal from horizontal in 'top' (48:14).

In that configuration, my average HR will stay in the 130s at a cadence of 80 in 'top'.

If I ride on the road, my HR seldom gets above 130 except on hills or if I crank up the cadence to 100+ in top (on the flat): I am loath to ride at any decent speed on the road because I am usually surrounded by people of median IQ driving 1500kg+ steel boxes - and I don't trust any of them not to kill me (assuming they're not actually trying to).

Yesterday I didn't have a full cask anywhere (I've been off the grog for six weeks, on a bet), so I just cranked it up until I couldn't move the pedal using my hand when seated next to the trainer.

This provided 'ample' resistance, to say the least: 2 minutes in, my HR was in the 140s although my cadence was only in the low 70s - and not in top gear, either - the average speed for the workout was 22km/hr.

Doing 'sprints' (15sec bursts at a cadence of > 130 in top) was almost the end of me.

Half an hour later, my HRM said I'd exerted ~500kcal over 10.7km, with an average HR of 148 and a peak HR of 166. The kcal count is about right for workouts where I do more sprints, and at a significantly higher average speed (i.e., a distance travelled of ~17km, reflected by an average cadence of 80 in top: cadence maps directly to speed via gear ratio).

So if I expressed this as "what is X in 48:X, to get that distance at a cadence of 80", the answer is "a little over 22". In other words, riding on (roughly) the 4th-highest gear, my HR was 10% higher than it usually is riding at the same cadence in top.

That got me thinking: rather than work out the effort above my 'wine cask' resistance level, I ought to be able to work out the 'effort above flat' implied by the level of resistance I dial in, by

• finding decent-sized bit of car-free flat (say, a 1km loop somewhere);
• going around it at a series of stable cadences (in top) and HRs (say, cadences of 80 and 100; HRs of 120, 130, and 140) each for a few minutes.

For each cadence, I would then know my 'steady state' HR on the flat (it will stabilise after a few minutes); for each HR, I will know what speed/cadence on the flat is consistent with that HR.

So if my HR is, say 10% higher (on average across the workout) than it was on the flat 'benchmark' for the same cadence in the same gear, I would chalk that one up as being '10% above the flat'. (I'm not pretending that's a 10% incline, or even a 10 degree incline; just that it's objectively 10% 'harder').

I realise that over time it would be expected that performance would get better, so there would be a need to periodically re-assess the 'flat' performance.

So finally the question: has this sort of analysis already been done and put up on the web somewhere?

I've googled terms I think might yield results, but haven't found a sausage. It seems to me that performance-metrics boffins would probably have solved this already (assuming it's an issue that has benefit for performance monitoring, which I reckon it does) so my search terms are probably a bit pants.

• Heart rate is sensitive to temperature, hydration status, duration, and fatigue, which makes your quest for an answer here even more difficult than for your previous question. Commented Oct 31, 2016 at 19:03
• How old are you? (approx if you prefer)
– Criggie
Commented Oct 31, 2016 at 21:35

That got me thinking: rather than work out the effort above my 'wine cask' resistance level, I ought to be able to work out the 'effort above flat' implied by the level of resistance I dial in

What you are attempting to do is calibrate your heart-rate on the indoor trainer to real-world riding - and this is far too complicated. Since there are so many variables to consider. Heart-rate is an indicator and not as accurate a measure as a power-meter. Your heart-rate can vary for the same effort over the same terrain depending on diet, recovery, fatigue and so on. Also riding outdoors there is the issue of weather conditions also - which can be for you or against you.

Another factor I can see is - although your indoor trainer attempts to provide a "road-like feel" - and all indoor trainers boast of providing the most realistic road-like feel. It will have a spin-down - that is the period which the trainer continues to spin after pedaling has stopped. This represents resistive inertia - good ones have excellent resistance and also take longer to spin down and have a nice "feel" to them when riding. So - your indoor trainer will not be a perfect representation of real world riding.

And don't forget - perceived effort - for me - indoors is often greater than perceived effort outdoors. I know for fact - my indoor power stats are lower than my outdoor power stats.

Personally, I would be setting the resistance at a single-level and changing through the gears to alter resistance. Looking purely at speed as a measure of your power - and using this as a basis for training. Might be a bit tricky - because it is speed and not power (everything is watts these days!). But you can combine this with your heart-rate data to know your speed and HR zones for training.

• I've been toying with buying a decent ('smart', Zwift-compatible) trainer for a while - until then I was trying to do things using shoestrings and sticky-tape. I was going to go 'all in' and buy a Wahoo KickR until it was made clear to me that I would need to buy another bike (because my gearset is incompatible with a KickR: my bike's a \$220, 15kg, clunker). Plus, The Lovely wouldn't give Royal Assent to the purchase until I 'got some time up' on the current trainer (a \$69 Aldi job) - today she gave me the all-clear, so I'm allowed to order a bKool Smart Pro.
– GT.
Commented Nov 5, 2016 at 3:43
• That's great news :-) Check compatibility of the BKool here support.zwift.com/hc/en-us/articles/… Commented Nov 6, 2016 at 0:16
• I eventually went for a Wahoo KickR and a new bike (a Merida Scultura). My Zwift avatar looks buff (6'1" and 104kg, as imagined by a bike-happy coder-geek, in Wahoo kit) and all my questions about power and what-not are superfluous because now I know the answer: big fat old blokes can put half-decent power to ground ('tempo' FTP of 271 - i.e., can do 285W for 20 minutes without getting HR anywhere near 'threshold')... but I'm totally pants at hills. Just like in real life - but with no "insecurity wagons" (SUVs) trying to kill me.
– GT.
Commented Aug 10, 2018 at 9:22

Might I enquire your age? This answer will be a bit vague without that, but you can work it out backwards.

The rule of thumb says that your max heart rate is 220-(your age in years) I'm 40, so 180 would be my "100%" heart rate.

This table shows cycling

This chart shows the "zones"

So your 130 BPM is likely to be the "weight loss zone" for under 50 or the Aerobic zone for over 50.

Back to cycling, my "tempo" zone would be 70-80% of 180, so 126-144 BPM.

Here's a short ride from last week - heart rate was above 160 for at least half, and a peak of 173. That translates to higher threshhold and into VO2, which is pretty good, giving speeds of mid 30km/h to a peak of 42 km/h. https://www.strava.com/activities/757787829/analysis

So to summarise - 130 BPM is a good "endurance" workout. You'd need to be doing that speed for a couple hours, and frankly that's boring on a trainer.

If you're dead against training on the road, try riding at a velodrome or some other kind of off-road track. An athletic track may work, or around the local park?

If you can work a decent climb into your trip then that will be excellent exercise. Use a tool like strava to measure your gains, cos it never feels faster.

• Its not a great answer but too long for a comment, and we can't post images in comments either.
– Criggie
Commented Oct 31, 2016 at 8:24
• I'm 51; the 130 is the average for a HIIT workout where each of the "sprints" gets my HR to 'max', with a sprint/rest split of 30-on, 90-off, usually done 10 times with steady-state (HR in the 120s) for warm-up and cool down - that gets me to 30 mins. Every now and then I do something more 'constant' for an hour (knowing that I won't wizz properly for two days: no amount of seat- and knick-padding can prevent my 104kg from causing pressure on the (ahem) 'contact' region... the legendary 'scranus'). I'm moving to a Zwift-capable 'smart' trainer in the next month or so.
– GT.
Commented Nov 5, 2016 at 3:10
• I forgot to mention: I do use Strava sometimes - the last workout (done with fewer, shorter, more intense sprints than usual to check the correspondence between sensors) is at strava.com/activities/759984056 (the peak speed measure is clearly a glitch!).
– GT.
Commented Nov 5, 2016 at 3:22
• @GT. Been there - anytime I ride the other-half's bike, I have to stand up almost the whole way. You might benefit from trialing other saddles.
– Criggie
Commented Nov 5, 2016 at 3:24
• I've tried every saddle type from 'big arse' saddles (chafe!!) to the ones that have two separate pads and no 'taint-destroyer' bits (that just felt weird, even on the trainer). I measured my sit-bone gap using the 'corrugated cardboard' tip (c-to-c was 140mm - I have Māori bum-bones... World Champs, Cuz!) and got a bike fit. A good mate who rides 'proper' races (A-grade seniors on a \$10k bike) suggested a useful solution: "HTFU, old man". The statistical risk of permanent taint-related damage from bike-riding is near-zero, but that's cold comfort "the day after".
– GT.
Commented Nov 7, 2016 at 0:23