Help, why so slow on 275 watts?

I am frustrated with how slow I am and wanted to see if anyone had some answers. Here is the data from a ride I recently did.

Weight 177 lbs
Bike 2020 Tarmac with stock wheels and tires
PM Stages left side only crank, installed when I bought the bike in May.
Distance 10 miles, rolling hills, nothing too steep at all.
Avg Speed 20.6 mph
Avg watts 275
NP 280

My ftp is 285. I would guess the effort level at 80%. I could have easily maintained 275 watts for over an hour and probably closer to two hours. I cannot figure out why I am so slow on that kind of power. I wore a cycling jersey and shorts, just regular cycling gear, nothing too loose fitting. I rode the hoods like I normally do on the road bike.

Is my PM likely reading way too high? When I rode the trainer all Winter, I used P-1 pedals, left side only, and my ftp slowly increased from 240 to 260. Once I got outside and started using the Tarmac, my ftp went up to 275 and then the last test it went to 285. I held 300 watts for twenty minutes in a test done a few weeks ago. Normally my VO2 max intervals are in the 300-315 watts range.

Many variables:

fit, wind, clothes, wheels, tires, tubes, pressure, helmet to name a few.

Fill in the blanks for us please.

There is very little to go on to judge. Your position, the nature of the hills, wind, any stops/starts in the route, turns, tires & tubes, etc. all factor. Also, unless you have a total power PM, there is no way to know if your single-sided is reading high or low. It could easily be off by 15W - 20W based on relatively normal power imbalances.

Here are a few example power-to-speed examples on a route I ride often on my road bike. This has rolling hills with a couple stops and turns that occasionally catch me. I usually ride about 75% on top of the bars and about 25% in the drops (totally a guess). Both were 20 mile rides on exactly the same loop route.
20.4 MPH; 235W; 1,460’ climbing elevation reported
20.3 MPH; 232W; 1,093’ climbing elevation reported
21.3 MPH; 255W; 1,516’ climbing elevation reported
Your ride at 20.6 MPH could be a little low on 275W. But, if you have a left leg bias, your are running basic tires on butyl tubes, the route had more elevation, and you rode upright the whole time, then you could easily have turned in a very fast time on that route.

Wind was 5-10 mph, nothing too crazy. It was two loops counter clockwise and I only had to slow for a few turns. I did not have to stop. Road surface is not great in one long mile slightly uphill section, but again it’s not a steep uphill. I use regular tubes that came with the bike. Tire pressure was 95 rear and probably 90 up front. I did not get professionally fit on the bike, but am very comfortable on it.

So maybe with the left side only crank PM, it is reading too high? I don’t claim to be a strong cyclist. I can climb hills really well even though I am carrying about 10 lbs extra weight around the middle, but I just can’t generate any decent speed with the Tarmac.

You did not mention tire model, so I will assume it is basic. Here are a few very quick power suckers based on your description, relative to my numbers…
Typical tires: -10W lossButyl tubes: -5W lossHigh pressure: -2-5W loss, depending on road surfaceRoad surface: unknown, relatively to my example on smooth asphaltPower imbalance: unknown
I have a 2% to 3% left side power imbalance. In my example fast ride, it was 52% L / 48% R. So, if I had a single-sided PM, it would have read 10W higher for me on that ride.

If you are pursuing speed, I would ditch your tubes and tires for a set with better handling and lower rolling resistance. That would give you an instant speed boost. And, you could probably lower your pressure 10 - 15 PSI. I run 80 PSI, and I am a lot heavier than you, thanks to my COVID weight gain.

177 pounds
.

I’m curious what you would think would be a decent speed for a road bike?

177 is kind of heavy for a rolling course, 5-10mph wind is a huge delta, and one-sided power is pure poop (personal opinion not grounded in science).

I’m going to go out on a limb and say the wind had more of an effect than you think, you’re too heavy (by your own admission), and your position is probably pretty upright due to where you’re carrying that weight. Not to mention that by your vague descriptions of your kit and equipment there doesn’t seem to be a lot of attention to detail, like: clothes that are baggier than they need to be, butyl tubes, tire pressure, helmets, etc.

but I just can’t generate any decent speed with the Tarmac.

Huge amount of variables involved. Shoes, tires, tire pressure, tubes, water bottles, helmet, clothing, cables, terrain, wind, road surface, shaved exposed skin, etc. are just a few of the things that are involved. I can sit up on my road bike (2012 CAAD10 with 50mm wheels) at 250 watts and be going 19 or so mph. On my tri bike in a good position I can do 25+ mph on the flats at 250 watts. In the drops on my road bike & holding a good position I am generally about 2 mph slower than the tri bike.

My guess is that you may have quite a few aero things to improve.

I rode the hoods like I normally do on the road bike.

At 177 lbs, over rolling terrain, while riding on the hoods…how fast were you expecting? 20ish doesn’t seem unusually slow given that. With a VI of 1.02…you would have to slow down considerably on the climbs…which you won’t make up descending sitting on the hoods.

Plugging some very rough, basic data into aeroweenie, gives estimates between 19-21 mph (80kg, 0.008 crr, 0.4 cda, 275 watts, 0-1% grade).

I admit I am too heavy right now, but I thought that weight was not a penalty on a flat course?

When I raced triathlons, I weighed 160 lbs, so I am a good 17 lbs over my former race weight. I used to run a lot back then (40-50 mpw) and now I only ride with one day of jogging on trails. I am a much stronger cyclist now than I ever was at 160 lbs though.

If I was able to lose 10 lbs, would that lead to a decent speed gain, or would it just improve my w/kg?

I admit I am too heavy right now, but I thought that weight was not a penalty on a flat course?

If it affects your position then yes. Also, did you not say it was a rolling course?

If I was able to lose 10 lbs, would that lead to a decent speed gain, or would it just improve my w/kg?

Again, how fast do you think you should be going? 20.6mph avg isn’t slow for what seems like non-optimized equipment and position.

I have read a lot of the thread on avg watts and mph and my speed is far lower than most everyone who posted a reply. I realize that many of the people were on their tri bikes, but still the difference in speed and power is substantial.

I guess I was expecting a lot more speed for the type of effort I was putting out.

I admit I am too heavy right now, but I thought that weight was not a penalty on a flat course?

When I raced triathlons, I weighed 160 lbs, so I am a good 17 lbs over my former race weight. I used to run a lot back then (40-50 mpw) and now I only ride with one day of jogging on trails. I am a much stronger cyclist now than I ever was at 160 lbs though.

If I was able to lose 10 lbs, would that lead to a decent speed gain, or would it just improve my w/kg?

Everything adds up, bad tires, bad tubes, bad position, extra weight on a ROLLING course. But, the biggest single factor is probably your position. Sitting up on the hoods is horrible—I guessed at a CdA of 0.4 for a larger guy sitting on the hoods in standard cycling gear.

You can go to aeroweenie.com and plug in the data yourself to see the impacts of the basic stuff. Its just for ball-parking stuff, though. For Example: the question you asked. I wasn’t trying to “pick” on your weight. Its probably not a big contributor by itself. But, it can impact CdA (sometimes for better, sometimes for worse…just kinda depends on how the air flows), and it doesn’t help with fighting gravity.

Almost every single person in that thread is posting stats from rides/races on their tri bike in full race kit (wheels/aero kit) and often with safe or closed courses. Of course it’s always worth trying to optimize your position and gear but comparing a road bike to that thread isn’t valuable.

I have read a lot of the thread on avg watts and mph and my speed is far lower than most everyone who posted a reply. I realize that many of the people were on their tri bikes, but still the difference in speed and power is substantial.

Man…that is like complaining you can’t see more than 15 feet at night while everyone else can see to the horizon during the day. If you really want to feel bad I can share some of my rides on my Time Trial bike. Think ~170w avg and 22.5mph on a flat(ish) course.

I’m gonna go with overestimated power numbers from your left side only power meter.

I’ve got lots of experience riding with power (PowerTap, Computrainer, Tacx Neo). I briefly had a left sided Stages and was getting some very unrealistically high numbers given my past experience. I eventually got rid of it and installed some Favero Assioma Duo pedals on that bike which returned power numbers in line with what I’d expect given effort level. One of the first things I noticed is that on EVERY ride my L/R power balance is always 55/45 or 54/46, i.e. I’m left side dominant. That’s no bueno when using a left side only power meter.

For reference, I did a 60 mile ride this morning with a group but had about an 8 mile section pulling into a very stiff wind (weather app says 13-15 this morning) over a rolling course. I was on my old school round tube titanium bike with Zipp 303’s and no aerobars (I was in the drops though). I weigh 166lbs at the moment. Over that section I averaged 19.1 mph and 188 watts (PowerTap hub). Early on in that same ride, I got a flat tire and told the group to ride on and I’d catchup later. This time with a stiff tailwind (10-12) I averaged 20.8 over about 9 miles on only 156 watts.

But, the biggest single factor is probably your position. Sitting up on the hoods is horrible—.

I know what you’re saying, but some hoods positions are pretty fast. I can generate more power and i’m guessing my CdA on the hoods is as good as in the drops. But you’re right, sitting up is horrible.

I have read a lot of the thread on avg watts and mph and my speed is far lower than most everyone who posted a reply. **I realize that many of the people were on their tri bikes, but still the difference in speed and power is substantial. **

I guess I was expecting a lot more speed for the type of effort I was putting out.

That’s exactly why people use Tri-bikes, and wear skin tight kits, and aero helmets. I’m about 4mph faster (give or take the width of a brick) on my TT bike vs. my road bike.

If I change the CdA to 0.25 (which is just an average TT CdA), and Crr to 0.004…you’d gain 4-5mph (give or take).

But, the biggest single factor is probably your position. Sitting up on the hoods is horrible—.

I know what you’re saying, but some hoods positions are pretty fast. I can generate more power and i’m guessing my CdA on the hoods is as good as in the drops. But you’re right, sitting up is horrible.

You’re pretty well known for being extremely optimized. The OP doesn’t understand the importance of it…so, it seems unlikely that his hoods position falls into the slippery category—unless by pure chance.

You’re pretty well known for being extremely optimized. The OP doesn’t understand the importance of it…so, it seems unlikely that his hoods position falls into the slippery category—unless by pure chance.

Agreed. Just wanted to make sure others reading don’t think that hoods is slow. You just have to make it fast.

and for a visual representation of what that “should” look like for those curious:

https://i.imgur.com/NI2IRcF.jpg

vs drops

https://i.imgur.com/yJrIsxp.jpg

ETA: found a better photo to compare drops vs “aero-hoods”