You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Please point out the flaws in this plan before I waste too much time on it...
I have a dumb turbo that I've been using to determine FTP using virtual watts (I ride to speed but I know what the trainer's power curve is so can work out target zones and/or results from FTP tests).
I want to use my rollers for longer sweetspot efforts because I like them and think they offer a better workout at lower intensities.
So - I warm up on turbo, do a 20 minute sweetspot effort, then jump off, transfer bike to rollers, warm up for 5 minutes (for benefit of roller/tyre temp if anything) then attempt to do another 20 minute sweetspot effort whilst maintaining same HR as I was doing on turbo. I already have an idea of what speed on the rollers would equate to a sweetspot effort so won't need to experiment too much.
Once I've figured out the right pace for the 'sweetspot' HR I can use this as a basis for future workouts (assuming I keep tyre pressure consistent and don't dramatically lose any weight!).
So where's the catch? I'm thinking that riding rollers might cause the HR to sit slightly higher given that you're having to work a bit more to balance on them, so I should really use the turbo HR and allow an extra couple of beats?
Also heart rate drift, the rollers will be my second interval of the session so I should assume my HR will gradually be drifting upwards anyway?
It should go without saying that I'm not aiming for absolute precision here...
Ta
Sounds all a bit "seat of the pants"! HR should really be used as an "output" not an "input".
I'm assuming that you are recording the data somewhere? Do the double 20min sweetspot interval on the turbo, that will give you a baseline so you have a feel for the HR drift along with tyre temperature, etc. Leave it a day or two then do your two intervals on the separate devices. But ...
Since it sounds like you have a speed sensor (which you must have to make use of VP) then set the turbo to the lowest resistance setting, which will be close to the effective resistance of the rollers, and work out your sweetspot speed from there.
Sounds all a bit “seat of the pants”! HR should really be used as an “output” not an “input”.
I agree, I'm doing it this way as I'm neither fast nor wealthy enough to just invest in a power meter or 'smart' rollers. However, point of my thread really was to try and understand what inaccuracies using HR as a constant might introduce.
Do the double 20min sweetspot interval on the turbo, that will give you a baseline so you have a feel for the HR drift along with tyre temperature, etc.
I guess I could do this to also get a better 'feel' for RPE which is probably accurate enough for sweetspot and would be a better exercise for real world riding anyway...
set the turbo to the lowest resistance setting, which will be close to the effective resistance of the rollers
It's a fluid turbo, wheel speed dictates resistance unfortunately.
I think the flaw is that just training to HR would be better than training to an attempt to calibrate your HR to power like this.
Well maybe, I'd just understood that HR was relatively variable, day-to-day, so using speed would be more consistent.
The two inaccuracies being HR drift (but I can use the Whitestone method to account for this 😉 ) and extra BPM required for balance etc. on rollers.
I'll give it a shot tomorrow, nothing to lose 😀
I'm just looking at the last sweetspot workout I did, 3 x 15. Taking the HR at two minutes into each interval, to skip the initial ramp up, and at the end, my figures were:
1: 128 to 140
2. 134 to 148
3. 146 to 153
That's pretty typical for me, around 10bpm rise across the interval and a ten to fifteen bpm rise between the first and last intervals. Just checked the sweetsport workouts before that (another 3 x 15 and a 3 x 20) and the figures were almost identical to within 2bpm. Often my notes state something along the lines of "my usual 10bpm HR drift across the workout".
So providing you've got the data I think you could get away with it. You might need to figure out what your HR gets to when you do say 3 x 20 at the top end of sweetspot so you know when not to overcook things.
Just curious, what's your max HR?
This is why I want to check my sweetspot workouts as I think I'm going too hard (even on the rollers, based on HR anyway) but then, I can usually finish them no bother (longest being 3x15). I often sit at 90% max HR for that duration which I'd always understood to be too high.
Edit: but thanks, great info. Will do as you suggest and just sit on turbo tomorrow and do 3x15, then next week use the rollers for second and third intervals.
Edit edit: for what it's worth, someone on slowtwitch had worked out a power curve for the Tacx Antares rollers (didn't provide weight or tyre pressure unfortunately) and it compares reasonably well to what I know, e.g. I suspect my 'sweetspot' speed on the rollers is 45km/h+. This guy's formula (W = 5.169 x speed - 30) suggests 51km/h.
Highest heartrate I've seen in the last six weeks is ~185.
www.crickles.org reckons my Lactate Threshold Heart Rate (top of Z4) is ~166bpm.
Z3 is estimated to be 147-156bpm.
Ooh, MHR is tricky, I've never tested for it. I know I can hold 175 - 177bpm for a couple of minutes so I'd guess at 185bpm. I don't actually know what my LTHR is either. I'm very much a diesel so long steady efforts are relatively easy for me.
Here's my 3 x 20 workout - https://www.trainerroad.com/app/career/bobw/rides/94196621-eclipse pretty sure it's public. I'm on a dumb turbo hence all the power spikes. You can scroll back and forth to see data at each point in time. My max HR during the workout was 160, did a bit of zooming in and it occurred at 1hr24 so probably a bit of standing up to ease saddle pressure.
Highest heartrate I’ve seen in the last six weeks is ~185.
http://www.crickles.org reckons my Lactate Threshold Heart Rate (top of Z4) is ~166bpm.
Z3 is estimated to be 147-156bpm
Snap, highest I've ever seen is 185rpm (specifically attempting a maxHR test).
Don't think it should be possible to sit at Lactate threshold for 3x15 min intervals? Pretty sure I climbed Rococorba at between 166BPM and 170BPM, and that was at least 40 minutes...
Edit: silly me, LTHR is equivalent to FTP heart rate, e.g. you should be able to hold for an hour...
Will assume that my maxHR is wrong, glad I've got (virtual) power now...
You could buy a powercal hr based power meter which, according to DCR, is pretty bang on for this sort of workout but not as much use for sprint intervals etc.
D'OH!
Completely flubbed my test run. Between changing cadence too much (annoyingly my target power was either 85RPM in one gear or 95RPM in the next gear) and possibly misjudging the effects of my tyres or turbo warming up (although Kinetics claim their fluid is thermodynamically stable over a realistic power range) my heart rate actually dropped slightly each interval, so hard to really take away anything from that!
I think already I'm just deciding to go back to plan A which pretty much involves sitting at 50x11 on the rollers at 85-90RPM which seems to maintain a heartrate approaching 90% maxHR.
As my dad would say (quoting Alvin Lee) - 'It's close enough for Jazz'
(translation: it's close enough for very amateur sweetspot efforts)
Or just buy a cheap pedal based pm?
Well I keep looking at them, £240 seems the cheapest rate going for a left hand 105 4iii.
Problem is, I think I would benefit much more from spending that money on something else, Rollers with resistance settings or the new drivetrain I'm going to need for the winter bike in the very near future...
On the other hand - if I paid the £240 there would be no more threads like this 😀
It was a useful wee experiment, I might try again by increasing the effort very slightly every interval, it would still be within the 'sweetspot' margin of 88% - 93% FTP (Coggan, apparently).
I also don't think there's any harm in going slightly higher HR on the rollers 'just to be sure' as although I'm calling it a sweetspot workout, in reality I'm taking an easy day the next day anyway so it doesn't actually matter if I go slightly too hard, in fact probably better as I can afford the extra recovery.
I'm looking ot sell my Left hand ultegra crank PM.. 172.5mm crank...
It's an avio power sense.. great powermeter, but.. it's ANT+ only, and I couldn't get it to play nicely with my PC, so went for a 4iii to use bluetooth..
Would sell it for £150 (on the crank, obvs!)...
If no one is interested at that price, I'll peel it off and stick it on my singlespeed!
DrP
It's already been suggested, but you need to stop mixing your 'currencies'. Measure what you can actually measure (which is HR), and use that to train to. Stop trying to convert to power etc.
Start the process with a 20 min FTP-type test, and then use the average HR from that to determine your HR zones for training.