How to Close the Power Gap Between Gym and Road

twotyred

On the road, although I can maintain the same power output as I can generate in the gym for short (less than 10 min climbs), for longer climbs of 20 min to 2 hrs I seem to have a 45-50 watt power deficit between what I can produce on the gym over a 2 x 20 min interval session.

I don't have a power meter so I'm using high school physics to work out my power output on road climbs (wt of bike and rider x 9.8 x height gain/time taken in seconds plus 10% for friction and wind resistance). I seem to be getting a consistent output figure over a number of various climbs of 4-10% gradients and different lengths. In the gym again I don't have access to an ergo-meter but I get consistent figures over a couple of different types of gym bike than have power output readings (Technogym and Schwinn spin bike).

OK for longer climbs I can't be expected to maintain the same power output as a 20 min interval but I reckon I should be able to get within 85-90% of it. My power measurements may not be that accurate and if the difference was 10-20 watts I'd put it down to experimental error but I think 40-50 watts is significant.

Any ideas about how I can close the gap? I'm thinking it may be the slower cadence and different body position of climbing on the road is somehow compromising my power output so I'm thinking of doing specific intervals on the turbo with higher gears and with the front wheel of the bike raised to simulate riding up a hill. Lowering the gearing on my bike to increase cadence on hills isn't really an option as my lowest gear is 35 x 27 and in any case my power figure on a rented bike with a 30 x 27 bottom gear was the same.

Anonymous

Two things...

1 - Never trust gym bikes' readings, I'd have a Functional Power Threshold of about 350 watts going off my local gym bikes (instead of what it actually is, about 270...)

2 - Theoretical power is, IME, miles out, far far too many variables to calculate it, even using sites like bikecalculator and analyticcycling (although the latter is more accurate than the former.)

If I go on a gym bike the power compared to the effort is nothing like what I get with my power meter...

The best test would be HR as that would at least be consistent between the two. Or get a power meter!!

Murr X

NapoleonD wrote:

Two things...

1 - Never trust gym bikes' readings, I'd have a Functional Power Threshold of about 350 watts going off my local gym bikes (instead of what it actually is, about 270...)

2 - Theoretical power is, IME, miles out, far far too many variables to calculate it, even using sites like bikecalculator and analyticcycling (although the latter is more accurate than the former.)

Spot on NapoleonD!

twotyred, you will probably be producing more power on the road than on the gym bikes due to several factors.


Murr X

twotyred

Was afraid the answer would be to get a power meter. Unfortunately finances preclude that and I find my heart rate too slow to respond to changes in effort and too affected by thermal compensation to be a useful training indicator.

Anonymous

twotyred wrote:

Was afraid the answer would be to get a power meter. Unfortunately finances preclude that and I find my heart rate too slow to respond to changes in effort and too affected by thermal compensation to be a useful training indicator.

Yet you think using different brand, wildly out gym bikes and on line computation may be viable? :shock:

HR does fine for me (and millions of others)...

Best sticking to perceived effort then.

ut_och_cykla

Yeah - heart rate monitor - doubt you're getting hotter on a summer hill than you would be in an indoor gym. Sure thermal effects play their part but ... and the heart response speed doesn't affect steady efforts over minutes /hours -
On a real hill there will your weight air resistance playing their part MUCH more than in the gym.
I've found this to be a good site http://www.noping.net/english/ for calculating/guestimating Watts out - but as with all estimations there are lots of things you can't check/control and there by it will only ever be an at best educated guess.

twotyred

I agree that for long efforts heart rate is more useful as an indicator. However I've found that for intervals of 20 mins that my HR is a lagging indicator and takes at least 10 mins to settle and that my ave HR for the second of two 20 min intervals at the same power output can be 10 bpm higher than the first interval so the conclusion I've come to is that for 20 min or shorter intervals HR is, for me anyway, essentially useless as an indicator of effort. As you say NapD its probably best to stick to perceived effort.

I knew using calculated power and gym bike power wouldn't be accurate but I didn't think it would be as wildly out as you've said NapD so thanks for that info.

smallangryman

20 mins is a fairly long interval!

HR might have trouble catching up when (for example) you are doing 3 mins at threshold or similar, but the lag really shouldn't be anything more than 30s.

And as agreed above, gym bike power is incredibly inaccurate. It may tell you the correct power one day, but only by chance!

amaferanga

I'd recommend using HR for your 20 min intervals with a little bit of common sense.

Stuntman

To be fair, you could use a structured power training regime on the gym bikes... they may be out but as long as it's consistent(a few tests of your heartrate on the same bike and gearing should show if it's consistent??) and use HR on the road?

twotyred

HR might have trouble catching up when (for example) you are doing 3 mins at threshold or similar, but the lag really shouldn't be anything more than 30s.

You say that but all I can say is what I've observed. At a constant power output at an effort that I can sustain for 20 mins and feels like threshold to me my heart rate takes about 10 mins to rise to a point where it then stabilises for the rest of the interval. For the second interval it takes less time to stabilise but as I said above that level can be 10 bpm higher than the first interval (probably because I'm hotter and more fatigued for the second interval). I may be a physological oddity but I doubt it.

To be fair, you could use a structured power training regime on the gym bikes... they may be out but as long as it's consistent(a few tests of your heartrate on the same bike and gearing should show if it's consistent??) and use HR on the road?

I've tried to use the same gym bike so even if the power reading won't be absolutely correct at least it will be consistent.

I've now stopped my gym membership so I'll probably just go on perceived effort and speed/gearing on the turbo to judge my efforts and start saving for a power meter.

Stuntman

and start saving for a power meter.

Me too. It's Something I've been intrigued about and a lot of people have said it's one of the clearest ways to train. Fingers crossed.

On a seperate note - The heartrate scenario for intervals might happen when I don't warm up properly. A few 10-30 powerups on the machine normally gets the top end of my heart rate working.

Anonymous

hopper1

I train using power...
At home, I use my Powertap and all is well.
I work offshore, and for the two weeks I 'm there, I have to use a gym bike. This does give different readings to my powertap, but at least they're consistently different!
So I train on the rig using a different set of power parameters.
I'm still making gains week in week out...