How "fast" is .10w/kg?

Over the past two months due to the stress of teenager drama, selling a house, trying to find a new house, etc, I’ve gained back some weight from my “race weight” for my A race at the end of February. Trainer time hasn’t been quality time, but I’ve still managed to get in about 2 rides a week so I feel my general “Fitness” has remained good, and I’ve lost about ~.10w/kg from where I was. It’s about 6lbs gained back and the Nokia + scale says thats about 2% fat(went from 15-17%) which isnt surprising given the poor diet choices involved.

Obviously like in this thread here I’m trying not to stress about this, but its really hard not to. I dont really know what I’m looking for here. Maybe just some words of encouragement about to not worry about it(which I know is also silly given how many threads here and the guys on the podcast say it).

But I also thought it might be a good discussion about how much .10w/kg matters. Why does the jump up feel so amazing, but the slide back suddenly makes you feel like you lost everything?

Don’t worry about it. Not getting stressed about the small weight gain will probably lead to a greater performance gain than worrying and trying to lose it.

FWIW, I’ve found it impossible to maintain race weight all year. I made a choice to gain a couple of kg, which can be lost again with some focus when needed. I’m riding better for it.

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.1w/kg is probably not even noticeable if you didn’t know the numbers


The answer is that it’s not very much, and whether that matters or not depends on your goals. If you’re a time trialist and have specific goals then it could be significant. If your goal is to have the highest w/kg possible for you then it matters a lot. If you want to do well in crits, probably not too much at all.

I think there’s value in using a “window” as an analogy to consider your wattage and w/kg numbers. Your numbers are just a window into your fitness, and not always a good one. Sometimes the window gets fogged up and it doesn’t tell you much. Sometimes the window is too small to see what’s going on outside. Sometimes the sun is glaring through and you can’t tell what’s outside the window at all. Regardless, your fitness is a larger thing that is only somewhat represented by a single number.

Your w/kg slipped a fraction. But what about repeatability of hard efforts over all sorts of durations? What about watts at other time durations? Has your endurance gone up? Has your HR at a given wattage gone down? What about motivation and recovery?

Your fitness may have taken a downturn, and the number is representative of that. But fitness returns. It goes up and down.

If you want to test out exactly how much .1 w/kg is, I recommend doing a TT on Zwift at whatever intensity seems appropriate. Do one at 2.9 and one at 3.0 on the zwift TT bike on the same course and you’ll have a pretty good answer.

I sometimes fret over this too, because my FTP hasn’t increased appreciably in two years. But I continue to do better and better in races, so I’m left to wonder how well mInor changes in FTP mean anything at all.


I think my w/kg varies more than that just in difference in weight throughout the day - it doesn’t matter. The good news is that the best remedy for a declining w/kg is riding your bike!

Yeah, from my A race to my B race a month later I let myself come up about 2 lbs just naturally by not stressing about the calories and I actually felt really good for the B race compared to the A race.

I’m certainly not trying to maintain race weight for the year, and I do need to remind myself of that for sure.

It’s amazing how too much information and tech can make us unhappy about something not worth being unhappy about. I’m guilty too so, don’t think you’re alone. I get frustrated at myself but every once in a while I am reminded how these little weight gains or loss in a little power just don’t matter at all in the big picture. Check out this youtube from The Vegan Cyclist. It encapsulates exactly what I’m talking about and exactly what happened to me (same race). Just a day after one of my best race performances to date…By the way, Vegan Cyclist put out some of his best numbers prior to this race (5.2w/kg!!!) Check it out:

It seems to me that backsliding on w/kg while keeping watts constant will mostly hurt your climbing performance and maybe your raw acceleration, but you’ll still be able to go as fast as ever on the flats. Don’t worry about it, you’ll get your w/kg back :slight_smile:

Base Weight: 70kg, FTP: 210, W/KG = 3.0

Heavy Weight: 72.4kg, FTP: 210, W/KG: 2.900

Base Flat km/h: 32.35
Heavy Flat km/h: 32.29

Base 3% Climb km/h: 20.74
Heavy 3% Climb km/h: 20.40

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Man, It didnt even cross my mind to look at best bike split.

I hate to mention another platform but zwift has modeled riding physics really… really well. Change your weight and do a quick trip on a climb or around a lap. You’ll see it doesn’t really matter in small amounts.

Personal anecdote… For the first time I’ve stopped worrying about weight and focused on watts and I’ve finally seen a lot of improvement in my sustained power.

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