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Indoor v Outdoor Power

  • 05-10-2022 2:41pm

    Hi there,

    I had an FTP of a certain figure last March before leaving the trainer behind and doing nearly all my training outdoors (including lots of structure) until last week.

    I'm back inside now except for a long ride at the weekend and signed up to Trainer Road to keep the training up over the winter.

    As part of the programme TR prescribed for me I started out with a ramp test and was taken aback that my FTP has gone down by 34 watts since March.

    This is despite training well over the summer and using the March FTP on my interval sessions and never once failing one or feeling it was out. I actually thought I was a bit low as I was doing 2 x 17 @ threshold with no issues and sessions like 5 x 4 @ VO2 max were also fine.

    I feel like a much stronger rider and was taking chunks off my PRs outdoors all summer which is why it feels strange that I'm after losing so much power.

    I checked my power meter and it's matching up with the figures TR is giving me so the power meter is not out.

    Any ideas why my FTP has dropped so much? Up to this point all my ramp tests had shown steady gains.

    Thanks in advance


  • Registered Users Posts: 9,104 ✭✭✭Macy0161

    Is it just the ramp test that has you low? fwiw I could never get on with their (or zwifts when I tried that as an alternative) ramp test and consistently under tested.

    Personally, I'd use the old FTP and then let adaptive training adjust if necessary, assuming you're following a plan and answer the survey's honestly.

    Also, in your "Account" go to "Early Access" and enable AI FTP detection. Then at your next ramp test you will have an Estimate FTP button, and not have to test. It'll replace the ramp test with a workout. I'm not sure whether it works on historical data, if you imported it.

  • Registered Users Posts: 5,738 ✭✭✭fat bloke

    I've a power meter nearly 10 years and I've always found indoor turbo/roller wattages to be lower than outside. Had a coach for a while and he assured me it was always the way. Why is another story, or you could just accept it, adjust your metrics a little and carry on :)

  • The ramp test is the only one I've tried. I did the ramp tests on Zwift last year and always got on fine, culminating in my final test @ 4 w/kg which is the one I rode to all summer outdoors.

    The minute I went back on the trainer, everything felt harder. For example, I rode 3.5 hours at 75% FTP about five weeks ago and yet I did 3 x 12 @ a little higher than that on Monday and I felt like I needed the rest after each interval. Maybe it's a psychological thing and I may need to just get ,y head around indoor training again.

    I'll do what you suggest, thanks!

  • Yeah, I think I'll just suck it up as I won't be doing many intervals outside anyway until next year. 34 watts is a big discrepancy, though, and would be the difference between entire training zones in some cases.

  • Registered Users Posts: 5,738 ✭✭✭fat bloke

    I suppose if you have an outdoor ftp and an indoor ftp then you recalculate your zones for each. I never did that, I just knocked back the indoor watts by 20 or so and also judged a bit on feel. Prob good to touch base with the outside world as well and do some outside interval work to remind yourself and compare feel and relative effort.

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  • Registered Users Posts: 9,104 ✭✭✭Macy0161

    Difference indoors and outdoors is normally put down to cooling. Personally, I was always brutal at the ramp test and then it got into my head so I was even worse. I used to estimate and/or verify with a a sustained effort. With TrainerRoad now doing AI FTP estimate I don't have to worry, and it uses all ride data and survey results.

    This article suggests you just need 10 rides with power data to use AI FTP.

    I know I'm a long term user, but with Adaptive Training and AI FTP, it really just becomes get on the turbo and train!

  • Registered Users Posts: 737 ✭✭✭Arthurdaly

    Same experience for me over multiple seasons. This year particularly I raced less and done more structured training outdoors from April until beginning of September. FTP was quite good and was performing workouts well on the road @ 4.3 w/kg.

    Went back indoors 5 weeks ago and the workouts were horrendous working off the same FTP. First two weeks were really hard going. I have just complete week 5 of training, I have progressed through the harder workouts off my outdoor FTP and feel on top of them at this point.

    The ramp test is not for everyone and you could have had a bad day. Outdoor workouts are just not as productive as an indoor workouts and if you analyzed your workout closer you might find you deviated from the workout with spikes and dips in power output as the terrain demanded or extended rest intervals.

    It's been quite mild so that will definitely impact your RPE and indoors will feel harder with it being less stimulating. For me it takes 4 weeks minimum adjust back to indoors especially using ERG mode on long sustained tempo/sweetspot workouts.

    Overall I would value an indoor FTP number far great than an outdoors FTP. If I get a good FTP number indoors then I would be confident of crushing it on the road.

  • Nice one, I think I'll be doing my fifth or sixth ride tonight so hopefully the AI will get going at 10 and I'll use it.

  • Thanks for the insight. I've been thinking about it and came to many of the same conclusions as you -

    Still very mild so cooling (overheating) an issue in my shed and probably don't have a good enough fan.

    While I was well able for all the outdoor sessions, it is hard to do sustained efforts with terrain. Also, I think I'm never as strict on rest between intervals outdoors.

    Last night's workout wasn't as bad as the previous few so hopefully I get my head and legs back around to the trainer now.

  • Registered Users Posts: 6,364 ✭✭✭iwillhtfu

    I always find FTP tests are just a number on the day you can feel great one day and hit a low number then half arsed another and surprise yourself.

    Definitely a big a fan as you can get if you're planning on racing on zwift at all.

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  • Registered Users Posts: 9,104 ✭✭✭Macy0161

    I've 3 of these on remote sockets. I brought them pre-brexit fully kicking in, but the updated "cadio" versions (which has a remote) is on amazon.

  • Registered Users Posts: 766 ✭✭✭duffyshuffle

    Invest in a strong fan and crank it up, even dress more if too cold from it, and it'll get a lot closer, without cooling my wattage would drop a lot.

  • Registered Users Posts: 3,409 ✭✭✭joey100

    This x100.

    FTP is fluid, moves depending how you feel on any given day. some days be little more others little lower.

    I found Trainerroad tough enough on erg mode, it gives you no deviation, locks you in at one specific power, outside you dip under and over. Just breaks up the constant power output a bit. A bit of a skill in managing that too.

  • Fully agreed on the second part of this. I wonder would I be better off switching off erg mode...

  • Registered Users Posts: 16,449 ✭✭✭✭dahat

    Erg for Zone 3 & below & for cadence based intervals works best for me on Zwift.

    Erg mode for threshold & above can be a negative session as the more fatigued you get the lower your cadence will be.

  • Moderators, Sports Moderators Posts: 23,880 Mod ✭✭✭✭CramCycle

    I remember seeing a video with TR and some elite athlete. Can't remember who but he said there is a reason you have zones and not hard numbers. Once your in the right zone, worrying about being at a specific number is a terrible way to train. As others are pointing out here, the day, you, the conditions can change things considerably.

  • Registered Users Posts: 9,104 ✭✭✭Macy0161

    Feck that, erg all the way for me. Trying to get the right gear/ right cadence/ right power just massively adds to the cognitive load for me - and negatively affects my consistency. I'm still waiting for a replacement belt for my turbo, and going back to the hybrid rollers has been a bit of a disaster (albeit the last couple of weeks of my season, and I'm ready for a break from structured training).

    I genuinely can say, even where erg has dragged down my cadence on certain intervals at certain times, it really didn't really affect my ability to push the same power at a high cadence in races.

  • Registered Users Posts: 16,449 ✭✭✭✭dahat

    Z6 erg mode? You’ve better legs than me!!

    Spiral of death is a horrible place to be 😂😂😂😂

  • Registered Users Posts: 9,104 ✭✭✭Macy0161

    No spiral of death without erg alright, as i'd still be faffing with the gears and roller tension!