Less Power Outdoors after Bike Fit?

Hey there Fascats. Curious if anyone has experienced this – I got a new bike fit in December. We went to narrower bars, longer stem, seat adjustments, etc. I am in a more aero/aggressive position. It feels comfortable. My back and neck hurt less, handling feels better, an on the trainer indoors, I’m nailing my workouts and hitting higher power targets than last year at this time by about 15w.

But, outside, I can barely hit the same watts I was doing last year. This hasn’t happened to me in my few years of training. Generally I get the bump outside that most riders see. Anyone experience this?

The kicker is that now that I’m getting deeper into the SS plan for this year, I am starting to set PRs again but my watts are basically the same as last year. Sometimes I’m taking 20-30s off of a half hour to an hour segment. I’m wondering if maybe I just can’t hold position as well when I’m climbing outside in this fit yet, while on a flatter surface I’m able to sustain the position more. I’ve noticed small changes in my body with this fit can push me up or down up to 30w.

Any insights would be appreciated. Thank you. :slight_smile:

My tuppence worth…this can happen when I use different wheels/helmet.

I cannot think of a reason why your bike fit would make you slower outdoors only. Especially since you said you are more comfortable, which should translate to more speed.


I’m with you. I don’t understand it either. But the trend has continued. The only caveat that I can come up with is that I am receiving immunotherapy shots for allergies on Thursdays and the effects linger for quite awhile. My only outdoor ride right now is Sunday. It’s quite possible that I’m stilly working through the increased allergen load through the end of the weekend and then feeling better by the time I get back onto the trainer early in the week…

-Do you use the same power meter indoors and outdoors (or, say, a smart trainer inside and power meter outside)?

-Have you changed power meters recently?

I use a Kickr Core (thanks to the FasCat Excel Sports discount!) inside but control it with my bike (Stages) power meter. Power meter is the same as last year on the bike so no change there.

I purchased the trainer in the fall so this is my first season using a smart trainer instead of a fluid trainer but didn’t really notice any big discrepancies prior to the bike fit.

Lots more questions (in my opinion there could be many things causing this)

-Stages single-sided or double sided?

-“Sometimes I’m taking 20-30s off of a half hour to an hour segment.”-For flat segments, climbing segments, or both?

-“But, outside, I can barely hit the same watts I was doing last year.”-What workouts are you doing this year? What workouts were you doing last year? Are you using the same training plan (so similar workouts) or different workouts? Or are your Sunday rides mostly fun/unstructured?

Answers. :slightly_smiling_face:

  • Stages single-sided.

  • Climbing. Interesting to note that the fit was of course done with me in a flat position and I wonder if that is factoring in. I have added a riser while indoor training in the last couple months thinking that maybe there is an issue with me being able to hold the position while climbing.

  • 18 Weeks of SS. Same plan as last year with updated FTP test. One difference on that is that I was getting 2 outside rides (about 3 and 4 hrs respectively) in a week last year during Covid, whereas now I am only getting one outside ride in the 5-6 hr range. Cumulatively, it’s about an hour less riding overall but my Sunday ride is a little more of a strain on the system. That said, I always do the intervals or SS segments earlier in the ride so that really hasn’t changed.

Since I first posted this, I’ve closed the gap of the indoor and outdoor, but am still seeing a little less outdoors than indoors.

Hmmm. Interesting scenario!

A few points:

-It sounds like you’re comparing sub-max data to sub-max data (none of your Sunday rides on 18 Weeks of SST should have max efforts, as far as I remember). Do you have outdoor FTP test data from the past or it’s all indoors? I’d be careful about comparing what you DID do and assume it’s what you CAN do; that’s why it’s important to test. Perhaps you’re fitter now but following the workouts more strictly.

-It’s odd you’re climbing substantially faster at the same power output, have you lost weight?

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Weight wise there have been no changes. If anything, I may have slightly better body comp than last year at the same weight.

Just to veer back a bit – the issue I’m trying to figure out is not so much a max power issue, it’s a discrepancy in the opposite direction of what is expected when I’m doing SS work. For example, last year my SS watts were 208 based on my indoor field test. I could do that inside on the trainer and outside as well, and get away with around 215 outside if I were doing SS intervals outdoors.

This year, my indoor SS based on the field test is 225. I have been able to do that indoors and hit my marks for the entire plan. But outdoors, I cannot hold 225 for probably more than a 3x8 and even that would be hard. It still feels like my outdoor SS perceived exertion is 210-ish. Yet, I did a 2x15 threshold workout halfway through the SS plan at 245w indoors.

Perhaps it’s all mental. I’m not really sure. I’ve felt good at times. I’ve been able to string together a good 5-10 or even 15 minutes here or there outdoors, but have not had the repeatability with those efforts outdoors since the fit. That said, in the last couple of weeks I feel like things are getting closer.

I do have an end/start of plan field test indoors this week and next Sunday I have my first Strava effort on the Strava Plan so that should give me a max power comparison.

Now that you talked in detail about your power going up quite a bit versus last year it makes more sense.
To me it seems like your legs/mind hadn’t quite adapted yet to 225 watt efforts outdoors due to the power variability when you ride outside… more peaks and valleys… 1 sec at 125w, the next second at 350w due to hills, wind, turns, etc. Also there is way less core activation on a trainer that occurs outside. I’ve ridden the trainer a lot the last 2 years due to an increase in training volume over the winter AND a broken hand last summer. While the trainer is great and a necessary evil it still doesn’t perfectly translate to riding outside. I would imagine your issue will evaporate as you get more miles in outside.

I’m stumped! Never seen this.

Honestly can’t think of any reason it would be bike fit. My gut feeling would be it’s a power measurement issue, although it’s hard to see why considering you’re using the same power meter indoors and outdoors.

I’m stumped, too! Taking everything in, it seems like @tgoods is on to something. It could just be that my core can handle the new position on the trainer better than it can outdoors at this point. I just did my indoor FTP test yesterday as I transition into the Strava Hill Climb plan. I have to do a maximal effort this weekend for that, so it’ll be interesting to see how they compare.