Indoor vs. Outdoor power. Increase? Decrease? The same?

[tonyzackery]

I don't have a Powertap, SRM, Polar, Quark, Ergomo, etc...to measure power outdoors. I've read of there being a perhaps 10% increase in average power output outdoors vs. indoors. What's been your experience ?

Apologies if this has been discussed to death before.

 

[grahamspringett]

I don't have a Powertap, SRM, Polar, Quark, Ergomo, etc...to measure power outdoors. I've read of there being a perhaps 10% increase in average power output outdoors vs. indoors. What's been your experience ?

Apologies if this has been discussed to death before.

It's not so much you get a power increase outdoors, it's just that it's mentally less difficult when you're outdoors, you can get out of the saddle more easily outdoors and cooling is not such a problem outdoors.

All these combine to make indoor numbers lower, but I have found that generally it's not a problem. I do most of my week-day training indoors, so when I get out at the weekend I have real fun, but it's not like I'm transformed into some frame-bending animal.

Another issue is that individual indoor trainers can have an influence on what you can manage. For longer intervals and steady stuff, a huge flywheel helps preserve momentum. When you're outside you can ease off the pedals for a fraction and resume without losing much speed and thus don't need to up your power to get back to where you were. Indoors is different - if you ease for even a fraction, wheel speed plummets and you have to really exert yourself to get back into your rhythm.

Ultimately, though, you do what you can. I've gone from 218 watts to somewhere near 275 (hopefully - going to test next week) on a diet of mainly indoor work over 2 years.

 

[Alex Simmons]

I don't have a Powertap, SRM, Polar, Quark, Ergomo, etc...to measure power outdoors. I've read of there being a perhaps 10% increase in average power output outdoors vs. indoors. What's been your experience ?

Apologies if this has been discussed to death before.

My indoor and outdoor power is the same but I have gone to a lot of trouble to enable that to happen.
See here for some thoughts on why differences might exist and what you can do about it:
http://alex-cycle.blogspot.com/2009/01/turbocharged-training.html

Previously, with a crummy mag turbo unit and a domsestic fan, I could barely ride 80-90% of intended power depending on level.

 

[tonyzackery]

Thanks for the information, gentlemen. Alex, you got a gold mine of information there on your blog. I'll be visiting that UK TT website for certain.

I should have been more clear in my question in that I'm somewhat familiar with the mechanisms involved in why a person may see an increase/decrease in power outdoors vs. indoors - I was interested in having the phenomenon quantified.

 

[frenchyge]

With practice, a good fan, and a good trainer the two can approach each other. In the last 2 years I've seen a noticeable, but small (~3-5%) increase in FTP after a few rides of outdoor re-acclimation.

Edit: Actually, now that I think of it.... there are no flat spots here for me to ride outdoors. I typically estimate my outdoor FTP using normalized power, whereas my indoor power is measured via average power. It's possible that the ~3-5% increase is a result of the different measurement/estimating methodology between the two.

 

[Alex Simmons]

Thanks for the information, gentlemen. Alex, you got a gold mine of information there on your blog. I'll be visiting that UK TT website for certain.

I should have been more clear in my question in that I'm somewhat familiar with the mechanisms involved in why a person may see an increase/decrease in power outdoors vs. indoors - I was interested in having the phenomenon quantified.

Yep, got that. As I said, for me the difference is zero.

 

[Fightin Boba]

I should have been more clear in my question in that I'm somewhat familiar with the mechanisms involved in why a person may see an increase/decrease in power outdoors vs. indoors - I was interested in having the phenomenon quantified.

Due to the variables that Alex outlines on his blog entry, the best you will get as far as quantification will be a wide range - probably 0-10% for most. Everyone will be operating with greater or lesser impairment from each variable, depending on how they optimize each variable. Alex has optimized each variable and now is at indoor = outdoor. For me, with a decent fan, a KK road machine trainer, and in the aero position, I'm in the neighborhood of ~5% less than my outdoor road position.

 

[rmur17]

just adding in another data point or two. I think it's a strong function of set-up as others have mentioned ...

My setup is: CT in the basement, temps around 12C up to 20C in summer, strong industrial main fan + 16" pedestal fan for 'trim' cooling. Old TV + VCR with lotsa old Tdf prologue, TT and mountain stage tapes (some back to the Indurain era!). Two windows close-by for ventilation (when it's not TOO cold outside). Good HRV unit on high to help keep humidity down. LOTS of water and some sugar-water close at hand.

It's a low-inertia setup but I mitigate that as much as possible by making sure I run the gearing/wheel-speed fairly high in ergo mode and by avoiding courses with steepish, sustained climbs (try to avg. from 35-45 kph). Pedalling thru mud every day isn't the most effective training IMHO!

So within those confines, over the years I've found most of the 'basement season' where temps are around 13-15C (summer is still an issue) power from a few minutes up to ~20min doesn't suffer at all compared to hard outdoor training. However, I still find some droop starts to occur around there that shows up, I reckon, as about 3% around the 30-min mark and around 5% at the full-hour mark.

Out past that, I believe the power loss is pretty constant - probably a function of the output power itself being sig. lower for say a 2-hr or 3-hr target session vs. hard threshold in the 30-60min region.

Now in summer when humidity is typically high and basement temps are 19-20-22C ... things are not copacetic. Generally speaking I'll stick to shorter efforts 20-30min long ... even <gasp> L5 work. Sustained hardish stuff just cooks me ...

All in all, I rate the power droop as mainly due to (still) inadequate cooling vs. good outdoor conditions. Then again, I suppose it hardly ever reaches 30C here so I'd have another complaint if it were that HOT!

 

[tonyzackery]

Now that I've got my PT SL (wired) going, I can say without equivocation that wattage output is far easier (PE-wise) outdoors than indoors. I notice that I utilize my upper body musclature for leverage/stability much moreso than when indoors. I can't quantify this difference yet, but I'll report back when I get a reasonably accurate percentage figure...

 

[kennf]

Now that I've got my PT SL (wired) going, I can say without equivocation that wattage output is far easier (PE-wise) outdoors than indoors. I notice that I utilize my upper body musclature for leverage/stability much moreso than when indoors. I can't quantify this difference yet, but I'll report back when I get a reasonably accurate percentage figure...

Yep, it's also the reason why your butt will get more sore for a similar time period when you're indoors. You tend to relax your upper body/ core.