Questions on Power/Weight ratio limitations

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As a long time cyclist I have read a lot about power/weight numbers. But not all bodies are created equal. I am 5’11" but with a relatively large frame. I was a competitive swimmer in college and have broad shoulders, a full barrel chest and large thighs. My orthopedic surgeon, who was both a triathlon event doctor and a competitive cyclist in college, does not want me below 190# (86.2kg).

That raises serious questions about how fast I can ever be, given my weight. So a few questions if anyone would care to posit a reply.

Is my weight in any way a delimiter to my ability to produce power, the power/weight ratio notwithstanding?

How much does weight matter on an indoor bike (I use a Kickr Bike)?

One other data point that may or may not be relevant, I am 66 years old. Thanks.

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Hi @Critmark what you might find I’m 55kgs my 5 seconds and 60 seconds aren’t great for my weight but my 5 minutes and 20 minutes are much better with my FTP being over 4 watts per kg. So you might find your 5 secs and 60 secs are much better than your 5 mins and 20 mins. I think sometimes it’s easier for heavier cyclists to produce higher bursts of power for shorter periods but maybe struggle over longer periods. As for age the only thing to maybe be wary about is your Lactate Threshold and do your efforts push you too far into the red, if that was the case you’d maybe have to watch that if your doing longer/harder workouts.

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No. In fact, being larger may allow you to absolutely produce more power, e.g. longer legs for more leverage, ability to develop larger muscles, etc. W/kg matters most when going uphill.

Almost not at all, other than it might help determine what 4DP rider type you have.

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Have a look at track racers. Those men and women are quite a bit heavier than your TdF climbers and produce insane amounts of power and go 50mph on the track. (That’s the current 200m flying start record)

As an example, Chris Hoy is 6ft 1 and weighs 92 kg, he won a couple of medals at that weight.

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You ask about how fast you can be. Well, how fast do you want to be, and how does that affect your cycling goals?

The only issue that I know of, is that if you do a lot of outdoor climbing the heavier you are the more you would have to overcome gravity. On the other hand, your ability to generate more power might counter balance it.

The only real way to find out is to do it, because without knowing anything about your physiology and your genetic potential, it is an impossible question to answer.

FWIW, I am older than you are, and about your weight.

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@Heretic not sure that I agree with the premise that outdoor climbing is the only issue here. Two basic laws of physics are also present. It requires more energy to move an object weighing 200# than it does one weighing 150#. Also, the greater mass of a 200# body creates more resistance than one 50# lighter. So two riders on the identical bike on a flat course, the heavier person would require more energy output to keep the same pace.

Also, is it a given that someone weighing more can generate more power? As you properly articulated, physiology and genetics play an important role in that equation.

Finally, let me apologize if I was not more concise with my question. I was not asking how fast can I be, I was asking does my weight, and it’s relationship to the power/weight ratio, limit my upside potential.

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Too bad that is not something that is remotely interesting to me. I prefer endurance events like 100 miles events and the longer distance triathlons. I tried track racing once many years ago and found it boring. Even the workouts were boring. To each his/her own I guess.

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It depends on the terrain and body composition.

If you live somewhere flat then no weight is not important. Well fitted clothes and a good position are going to matter far more.

If you live somewhere hilly then weight will have a bearing. However dropping weight is only beneficial if you can maintain power (or lose it at a lower rate than your current w/kg).

I think the final point to consider is your 4dp. If all the hills in your area are 3 minutes long then increasing your 20 minute power might not be the best strategy to “go faster”. You might get as much bang for your buck working on your 5 minute power and improving your riding position.

As my grandma would say “there’s more than one way to skin a cat”

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Looking at this model, you will see that body weight does not matter much on the flats. On a climb there is a difference.

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Outdoor climbing may not be the only issue but it is by far the bigger issue. On flat ground the physics mean weight’s only an issue when accelerating up to speed, once you’re there the impact is marginal if any at all. The far bigger impact is wind resistance and a heavier rider with more power to push generally does better in the wind.

Once you’re at speed, think of an analogy to rowing. Weight absolutely has an impact on the speed of the boat, bigger impact than with cycling because your base coefficient of friction with the water is generally greater than the friction of your wheels, and I believe increases more with weight. Yet despite this on average, all else equal, crews with larger individuals are faster, because they are stronger.

Accelerating to speed will be an issue sure, so a course with lots of sharp corners that make you bleed speed could be an issue. But this can be mitigated with technique and note, successful crit racers in the US, CXers and MTBers are often / generally meaningfully larger than top GC racers, again because although they are big, they are also strong, they go faster on the flats and even the negatives / acceleration issues are not enough to outweigh this.

Don’t lose heart if you like longer endurance events, the best classics risers also tend to be on the bigger side because they are strong and tough and spend a lot of time in the wind. (Think Tom Boonen).

They key assumption here isn’t about what cycling events you want to do or duration, rather it’s the assumption that more size = more power. This is not always true but it very, very often is; more muscle equals more force production and greater anaerobic capacity.

So I’d suggest your path forward include the following:

I. Train for whatever events you enjoy the most
II. Don’t spend all your time bench pressing / skipping leg day
III. Most important, do not get the idea that just because you’re big, you can’t also be fast. Learn the situations in which your strength works for you and in which it’s a hindrance, and learn to maximize the former and mitigate the latter.

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That was a question I asked in a response above. Hopefully in my case, yes.

I was thinking about my two favorite imperial century rides. One has two hills that are both long and steep. The other only one hill, and while just over 15 miles long with a max gradient of 14%, has an average gradient that is very low. Not surprising, I enjoy the latter much more.

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Thanks for the link. Doing some basic calcs does reveal some interesting numbers:

Watts needed to maintain a 20 MPH speed for a 150# rider vs 190# rider, flat road, everything else being equal. The 190# rider needs to produce 4.6% more watts.

Watts needed to maintain a 15 MPH speed for a 150# rider vs 190# rider, 3% incline road, everything else being equal. The 190# rider needs to produce 17.9% more watts.

3% is not a tough climb yet requires a lot more watts from the heavier rider. 4.6% more power from the larger rider seems like a reasonable hurdle, even a small incline of 3% requiring 17.9% more power seems a lot harder to deal with.

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The sound quality is pretty dire, but Willie Smit has an interesting video about power/weight ratio and climbing here:

He sums it up in a reply to one of the comments like this
"In basic terms all I am saying is that on a 6% gradient a heavier rider like myself @75kg ride at a lower w/kg than Sergio 57kg for the same time up the mountain. Same speed. However you want to put it. In theory if I am riding a lower w/kg than my partner , in theory if our fitness levels are the same it means I’m burning through my stores at a lower rate and Less lactate /muscle damage in the legs. "

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@JohnK I understand the point but it carries an inherent flaw. If the two riders are riding at the same speed does not mean they are exerting the same effort. If the lighter weight rider is riding at 80% of maximum power and the heavier rider is doing so at 90%, then the logic fails.

There are multiple variables here and the comment is not factoring in all of them. Weight and watts are the only two. It ignores effort and assumes fitness levels are the same. Even if you do assume fitness levels are the same, effort levels are completely ignored.

I have done many a group ride where at the top of a hill I am huffing and puffing unable to speak and a rider 40# lighter is carrying on a normal conversation. This isn’t a perfect comparison but you get the idea. We arrived at the same place at the same time

same time up the mountain, Same speed

but our effort levels were vastly different.

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Well, Willie is talking abut elite level pro riders with very low body fat so not entirely relevant to mortals like us!

But as I understand it his point to hinges around “same fitness” meaning “can produce same w/kg for same effort level”. It that case, for gradients up to around 7% the heavier rider has an advantage.

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@JohnK I understand the point, but am having a difficulty reconciling the numbers. Using the calculator that Heretic posted above, the watts necessary to maintain a 15 mph speed on a 7% for a rider at 150# (440.77 watts) and 190# (531.86 watts) does not seem like any advantage. That’s 20.67% more watts. The question has been asked here, does a heavier rider actually produce more power. You added the qualifier “same fitness” which is appropriate.

So the revised question is, is it reasonable to assume that a rider of 190# can produce 20.67% more power sustained on a 7% climb than a rider weighing 150#. I have no empirical evidence one way or the other but on its face, the numbers seem to suggest that it is a stretch to say the heavier rider has an advantage. What am I missing?

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@Critmark , by Willie’s definition of “same fitness” I would expect the 190lb rider to put out 26.7% more watts in absolute terms than the 150lb rider BUT, Willie talks about “a big guy like Wout” who is 6’ 3" and 172lb. i.e. big for a worldtour cyclist but not “big”!

I agree that at (say) club-level cyclist it is unlikely that the 190lb rider puts out 26.7% more power than the 150lb rider for the same perceived effort, but then again you don’t see many worldtour pros weighing in at 190lb.

The take away I got from it was that body weight is far from the only thing that matters, particularly on lower gradients. But yes, he is specifically talking about elite level riders, which I certainly am not and never will be! Overall I just thought it was an interesting video and showed calculations which I had never even considered.

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I guess it is less about the gradient and more about how fast you can go. If you can go up an 5% slope at 30kph aerodynamics still matter.

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@Critmark Here is a simple anecdote - I ride MTB (and sometimes road) with my neighbor and we have roughly the same W/kg (about 3.6) despite me being around 73kg and he being around 95kg. We raced together in a 50 mile MTB race back in September and he came in slightly ahead of me which he joked was because gravity makes him faster on the downhill segments. I can usually sprint faster and climb faster than him but he is probably better overall at endurance.

Weight is just one piece of the puzzle - there are many other factors: lung capacity, lactate threshold, types and strength of muscle fibers, development of capillaries in the muscle, energy efficiency, VO2 max, ability to recover quickly, overall mental toughness, etc. We are all built differently and have to work with what we have and try to improve on our strengths and minimize our weaknesses.

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I am not aware of any physiological fact that would give large or small riders an advantage in ability to sustain power over an extended period of time (I.e. in FTP). If that’s right, the best climbers should be smaller (because of higher FTP/kg)—which they are.

For short duration power, I suspect that muscle size and strength matters a lot. That would suggest that for short duration power, the best riders would be bigger—which they generally are.

Since road sprinters also have to ride the rest of the race and climb well enough to avoid getting left behind, you’d expect that they would be bigger than climbers, but not big by normal standards—which they generally are.

I’ve not looked at the weight of track sprinters, but suspect they would sometimes be appreciably bigger than road sprinters because they don’t need to do anything else. From a raw speed perspective, I imagine (but haven’t confirmed) that they are the fastest.

So bottom line: being big doesn’t limit speed in any absolute sense, but it might have an effect on the environment and duration in which you would expect to be fast relative to other people. Of course, if you get really fit and ride with small, less fit people, you’ll be the fastest in almost all environments.