Threads are so much better with photos!!

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Well this is eye opening. I need to get more optimized on my road bike. :-(

Even if you include variables like wind, tyres etc that's still a lot of power for 20.6mph. I'm a little bit lighter than you, for IM, I rode at 21.7 mph with 180w NP. Faster speed and almost 100w less.

And you rode at 97% of your FTP for over an hour!? My FTP is similar to yours, I would be hanging out my arse after 20mins if I rode anywhere close to my FTP. Sounds like your PM needs to be re-calibrated. Past 220w it should start feeling hard.

+1

I've got similar weight and power stats, nothing too special on the bike save for the GP5000, 20-21mph solo on a flat course with little wind at 275 sounds good to me. If I want to worry about speed, I'll get on the tri bike!

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808 > NYC > PDX > YVR
2024 Races: Taupo

I'd also say it's more in your PM than clothing or the rolling resistance of your tires..

I'm only 5'7" and 146-148lbs, but with tight fitting cycling gear and just regular cycling shoes/socks and a Bontrager Ballista helmet on the hoods or in the drops I was averaging 24-26mph on a slightly undulating course (had to cross 2 bridges over the highway each lap of 7k and some false flat parts in between) on 270W (Favero Assioma Duo) for 20' intervals. I'm on a SystemSix with 60mm wheels and a decent position.

For reference, I did a triathlon last Saturday with about 1250m/3750ft of climbing in 62k/39mi on 235W avg and 267W NP and I still averaged 20.2mph.

Those bits add up for sure and probably are more than you're giving credit to, but the major thing here is likely their position on the bike. Don't be too quick to fault the PM and discount all the obvious issues.

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As one or two others already commented, you actually don't know how much power you're producing since you are using left side only with both of the PMs you've used. I've described single sided PMs as power estimators on ST before and some people tend to get annoyed, but I think it's a fair comment. Your PM is only measuring the output from one leg. Extrapolating that to a total power figure and treating that as a piece of real data for this sort of analysis is a problem. There are too many assumptions as to the power being produced before you even start thinking about where it might be wasted/spent.
Also the much higher values you're getting outdoors could reflect better performance by you, or that the indoor PM was measuring low, or that the current PM is providing rather optimistic values (meaning inaccurate on the high side).

Prime suspects:
Inaccurate power data (left only can produce massive inaccuracy if you've got any significant imbalance and this is on top of existing sensor tolerances.

Say you've got a reading of 275W from doubling the left reading. So it's measuring 137.5W on the left.
A 45%/55% imbalance would be nothing remarkable. If you're typically producing 55% of your power on the left for this sort of effort, then the corresponding left leg power would be 112.5W. that's 250W total power, not 275W. Then say your PM has 2% stated accuracy. Even within spec that's potentially another 5W so could actually be working with around 245W with everything working normally and unremarkable imbalance. That's a full 30W less than you're assuming you have.

As others have said, there are then all the places the potential speed available from that power can be squandered.
Almost all of your power will be spent doing one of 4 things:

1. Moving air around
2. Gaining altitude
3. Deforming tyres and tubes
4. Wearing out your drive train

You're on a road bike in an unknown position on the hoods, with not particularly low drag clothing going by what you've said. At this sort of speed on flattish or rolling terrain, most of your power is almost certainly going into no.1 above, so it's likely your biggest issue is high aerodynamic drag and position and clothing will be the biggest contributors by far.
It's pointless to compare your speed on the road bike in relatively casual position and clothing, to other peoples race splits on a tri bike with everything optimised. The difference in speed for the same power can be rather significant. And that's assuming the power values are actually comparable and that their weather, terrain and road surfaces were kinda similar.

For very flat or gently rolling terrain, altitude is probably not a massive impact, though flat would still be faster in almost every case. So we'll skip past no.2.

Stock tubes and tyres is unlikely to be helping you. I don't know what Specialized put on their Tarmacs but it's likely you can do a lot better.

I don't suppose your drive train is a mess of thick lube residue and dirt? Maybe lots of wear, corrosion and damaged bearing for good measure? If so, great! -Easy speed. If it's all pretty good, you might still retain a couple of extra watts with a better lube.

I rode for 30 minutes, not an hour at that power. Yes it felt hard, but my breathing was under control the whole way. As I said, I could have kept going for a long time at the same effort.

I appreciate all of the responses, this is very helpful information and puts things in perspective. Given the left side only PM, it is likely that a dual sided PM would register a lot lower power number. I did not want to spend the money on a more expensive PM when I just dropped over 4k on the Tarmac.

I have a question about tubes and tires though. I have a new pair of Conti GP5000 tires that I could put on the road bike. If I switched to those tires and bought better tubes, would I likely see a difference in speed? And if so, what type of tube should I be looking for? I have just always bought the cheap older style tubes that have been used for decades.

GP5000 are good. That's what I'm using myself. Latex tubes are fastest, but have some trade offs in simplicity of installation, air leakage over time, and potentially heat damage - but that's not likely unless you've carbon rim brakes which you drag on long descents and insufficient rim tape.

I use latex on my tri bike and usually butyl on my road bike. I could use latex on both but I'm less bothered about absolute speed on the road bike.

No idea what speed gains you'll see without knowing what you're changing from.

It's a potential explaination for your speed being lower than you expect, but maybe that's not it. Maybe you're just quite aerodynamically and mechanically inefficient, or you're misjudging the impact of wind or terrain.

The point is you don't know your actual power and it may be less than you think.... but it also may not.

Ditto above. The GP5K are one of the top tires and what I race on. If you switched to those tires, installed Vittoria or Silca latex tubes, and lowered your tire pressure to around 80 PSI, you would probably instantly gain about 15W of efficiency. Imagine that... it would be like you increased your power by 15W by just swapping in a few parts.

If you're training with a PM, then why are you even concerned about the speed? To me, the power numbers are just numbers to use for training purposes. There are way too many variables that impact your speed (and HR), this is why people spend money on a PM.

It really doesn't matter if your PM says 200 watts at a given effort or 400 watts, as long as it is consistent. If you want to go faster at your current level of fitness, ride a faster bike or make changes to your position, kit, wheels, etc.

This is true, but I'd be annoyed too if my PM seemed significantly off. Makes it harder to participate in group discussions about power, and also could make your Zwift reality and results a lot different than your real world results.

Yes, and no.

For racing, the purpose of power is to produce speed.
You don't win races for having the highest power output.

If, based on either training or racing, you think you see an inconsistency between the power you appear to be producing and how fast you're going compared to others, it's perfectly reasonable to wonder why. So the OPs query is reasonable, but the answer is that there's any number of reasons and the actual power data isn't terribly useful as a simple analytical tool in this scenario. There are too many unknowns.
The answer for how to go faster is the same with or without power data. Reduce aerodynamic drag, rolling resistance, and mechanical inefficiencies, thus increasing the speed at which these losses equal your power output, at which point you stop accelerating.

I recently purchased a Roubaix (5k) and went with the Stages PM for same reason as you. It’s pretty darn close to my Powertap numbers from my tri bike. Also, the S-works turbo pro are durable and fast with latex.

Do you have a smart trainer that registers power? If so, what is the difference between what your smart trainer reads and what your PM reads? You can test by recording a ride on Zwift (or similar) with your trainer's power and recording that same ride on your Garmin with your pedals and compare the files in Zwiftpower.

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Janyne

How do you like the Roubaix?

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Janyne

Well, for context I haven't really ridden a road bike in about 20 years. Looks great, rides smooth, shifts like butter (DI2), solid braking, very comfortable! I did think I'd be faster on it that what I first experienced and that is one of the reasons I bought the Stages PM. The power numbers I've seen so far are similar to my TT bike and I'm between 1-3 mph slower on it. In fairness I'm still "learning" to ride in a road position. And speed wasn't the #1 reason I bought it; it's probably my last new bike purchase and I wanted something that would take me into the twilight of my road riding career.

Very nice!

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Janyne

This thread is an enjoyable read, but not for the right reasons. AP vs Speed on a road bike out on the road is like SWOLF in the pool. It doesn't mean anything in a race (or group ride). The only thing that matters is did you hit your power targets (If solo), did you finish with the group (in a group ride), and did you finish with the pack (in a race).

There are too many variables that only exist on a road bike out on the road. In a race or group ride I don't even display power, and when I load it into GC I'm only interested 5, 10, and 30 sec peak powers - did I minimize the jumps, and when I did jump has my power improved.

On a road bike tire wear, flat protection, and comfort trump everything (except cornering if you also race). Clothing is what is comfortable and makes you visible. Helmet is all about fit, safety, and ventilation. Position is also about comfort and handling.

I laugh at the aero road bikes. They mean something to the guys riding on the pointy end of the chart, but not to the average rider. I rarely see one at a closed course race. Bikes like the Allez are all you see. My "fancy" Roubaix is an anomaly, but I'm getting old and the Allez was killing me.

Train on the road bike and forget about AP vs Speed.

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"...the street finds its own uses for things"

Last night on my road bike I did some VO2 stuff. One lap is 80ft per mile avg elevation. Uphill hitting it hard at 350-400w, downhill spinning the legs out at like 90 to 110w. Avg lap was 220w, avg speed was 21mph.

21mph, road bike, 80ft per mile........220w avg.

I know bigger riders take more power, but 80ft per mile would be 8000ft in a 100mi ride. 270 or 275w and 20.5mph even for an 80kg rider just sounds too slow.

I've done metric centuries at 50 to 55 ft per mile around here on the roadie on only 205w AP for right at 20mph.

If you time trial or hill climb and having the power really really MEAN the power in actuality so you can do "math", I would fix your setup. If you're just training and need something that reads the same day to day, you're probably fine.

And you believe the power numbers posted on ST? OMG

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Live long and surf!

I think you should go out and find a flat section of road on the least windy day you can and do some test runs. Something like 3 to 5 min long, do them 4 or 5 times and see how consistently you can repeat power to speed. In fact you could make runs at different consistent powers and discover the speed. By getting different power to speed measurements I can not only calculate cda but crr as well. If you do them all in a short time period there would be less variation in air density and i could just use standard air density, but to be more accurate I would need air pressure, temp and humidity. I really think there's something fishy with your power measurement though.

From what you posted you have a cda of .44 and that seems really high and you should be able to improve that.

Now I'm a lot smaller than you but from testing on a velodrome I get .245 on my track bike while riding in the drops. If you can drop to .4 you're going to drop about 20 watts to go the same speed. Down to .35 and you're going to drop 44 watts to go the same speed.

I really think you're capable of doing that.

I don't know what cda means, how to measure it, or how to improve it. I assume it means aerodynamic efficiency?

How would I go about trying to improve cda and therefore my speed at lower watts? Ride in the drops? Switch tires and tubes to Conti GP5000 tires and butyl tubes?

BTW, I don't really race much anymore, so trying to get faster on a specific loop I ride is the goal to keep me motivated when riding outside.