Gravity: Friend, foe, or neutral?

[RPS]

I’d like to hear different opinions on how we should assign significance to “gravity” when discussing its effect on riders of different sizes; particularly as it relates to climbing and descending.

We often hear gravity being included as a factor when comparing how small and large riders climb and descend, but does gravity itself have anything to do with it?

The general idea often expressed by cyclists is that gravity is kind to small riders on climbs and kind to large riders on the descend. But isn’t gravity exactly the same for all size riders? Isn’t its specific effect impartial or neutral? Therefore, why is it easier for large riders to blame gravity on climbs instead of saying that they don’t have as much specific power as their smaller friends? Not that that’s always the case anyway -- I’ve been passed on climbs by larger riders many times.

Likewise, when large guys fly down a steep descend faster than their small buddies, why don’t they thank having less specific aerodynamic drag than their smaller friends? Why thank gravity instead of favorable aerodynamics?

I know its semantics for the most part, but why involve gravity at all if it’s always the same and an impartial participant? Or is it not neutral to different size riders?

[Louis]

Gravity's not the problem. Drag is the problem. Because drag is non-linear you loose more energy at higher speeds as you descend. Were it not for that, it would be much easier for the heavy, slow ascender, to catch the light slow descender on the down side of the hill.

[link]

Hey RPS, I though I'd share some anecdotal experience instead of giving the more obvious strength:weight comment.

My weight fluctuates between 157 and 180. Right now I'm holding onto 157. I must say that climbing at 157 is so much less fatiging than when I'm heavier. Being less fatigued, I maintain better form through the 20 to 60+ minute long climbs that are around my area. Also my overall speed is more consistent and faster overall on the longer 5 to 10 hour rides that require multiple climbs.

Since the riding time around here is basically divided up as 80% climbing and 20% descending, I'm going to give the nod to less mass for faster and less fatiguing performance.

I do feel that there must be an optimal weight for the type of terrain a cyclist encounters. Also, I think there's a limit to how light I can be and continue to be strong. I can't see myself at 135 and being faster on the climb than at 157. But I could be wrong. I've never attempted to drop below 157. I'm already pretty gaunt looking at 157.

Aerodynamics seem to play a bigger part in descending than weight. Although I do struggle to hang onto the descending wheel of a strong tandem team. Those guys fly down the hill.

[Waldo]

One of the best things I've heard on the subject is from a friend, who said, "I have a love-hate relationship with gravity." (!!!)

[MattTuck]

yes, power/weight ratio is critical. if a big guy can produce proportionally as much power as a smaller guy, they'll climb at the same rate.

as far as descending. There are very few descents (atleast around here) that you can completely let loose on... whether turns, crappy pavement or cars, you usually can't take full advantage of gravity.

[Sandy]

Gravity is a friend to lighter cyclists and a foe to the heavier cyclist. It is not neutral:

Assume that you are going up a 5 mile hill at 5 miles per hour and immediately, after the climb, down a 5 mile hill at 25 miles per hour. Your average speed is not the average of the speed up and speed down the hills-(5+25)/2 = 15 mph. It takes you 5/5 or 1 hour to go up the hill. It takes you 5/25 = 1/5 hours or 12 minutes to go down the hill. Your average speed for the whole 10 mile trip is (10)/ (1+1/5) = 10/ (1 1/5) = 8.33 mph. The 8.33 actual average is way below the average of 15. It takes much more time to go up the hill than down the hill so the average for the trip, up and down, is skewed towards the average up the hill. A heavier rider is at a strict disadantage (normally) to a lighter rider since it takes longer to go up then to come down.

Look at the weights of the Tour riders- There will never be a 250 pound winner of the Tour. Too much climbing. There will probably never be a 250 pound Tour rider. The only way there could be a 400 pound Tour rider would be if they let him finish sometime in September or later.......


:) Skinny Sandy :)

[KevinK]

Being a decent climber and a lousy decender, I have thought about this often. My conclusion: Its not a zero-sum game; gravity has much more of an impact on climbing than on descending.

The supporting math: lets say you have a 2 mile stretch of level road. If you average speed is 20 mph, you will cover the distance in 6 minutes. Now let make it a mile long climb followed by a mile long decent. If you climb the hill at 12 mph, you will reach the top in 5 minutes, and you will have to descend at 60mph in order to make up the time. If the hill is steep and you climb at 10 mph, you will have used all 6 minutes just going uphill, leaving you no time to descend. So my strategy has always been to bury myself on the climb and don't worry about saving energy for the descent. Which is probably why I am lousy going downhill.

Kevin

Sorry for the redundancy. I composed this before I read Sandy's analysis. We are on the same page!

[false_Aest]

Theoretical hypothetical babble:

2 riders.
same skill.
same bike.
same height.
One is 5'8" 140 lbs
the other is 5'8" 160lbs

Racing UP or UP/DOWN the svelte dude is gonna win.

Racing DOWN big dude is gonna win.

More about the race than gravity.

[MattTuck]

More about the race than gravity.


Still waiting for the down hill time trial, in which heavier riders would dominate.


They did Alp D'Huez going UP a few years back, they should add in a stage going DOWN.

[OtayBW]

Gravity, drag, aerodynamics????

I'd have to say 'nah'; for me it's inertia. That can get you before and during your ride.

[Dekonick]

UP = enemy
DOWN = friend

:cool:

[Clydesdale]

But this is from an article found Here (http://www.sportsci.org/jour/9804/dps.html)

"Scaling reveals that larger cyclists have a greater ratio of mass to frontal area. They therefore descend hills faster as a consequence of purely physical, not physiological, laws. Since the larger cyclist has a greater mass, gravity acts on him or her with a greater force than it does on a smaller cyclist. (Note: A common misconception is to note the equal acceleration of two different sized objects in free fall in a vacuum, and assume that the force of gravity on both is equal. The force on the more massive object is greater, being exactly proportional to mass, which is why the more massive object is accelerated at the same rate as the less massive one.) While the larger cyclist also has a greater absolute frontal area than the smaller cyclist, the difference is not as great as that for their masses. Thus, the larger cyclist will attain a greater speed before a balance of forces results in terminal velocity."


I guess that's why weighting pinewood derby cars is illegal and why I can coast by my 75lb smaller riding partner downhill while sitting upright even when he is in full tuck. [the only time I ever pass him] Sign me up for the long straight downhill coasting tt anyday. :rolleyes:

[RPS]

Gravity is a friend to lighter cyclists and a foe to the heavier cyclist. It is not neutral: Being a decent climber and a lousy decender, I have thought about this often. My conclusion: Its not a zero-sum game; gravity has much more of an impact on climbing than on descending.Sandy and Kevin, I get the math, but I’m not questioning whether hills or mountains on average slow riders down – I think that’s pretty much a given.

My question is more directed at how hills and mountains (because of gravity) affect little guys differently than large guys and vise versa.

Technically, gravity has the same effect on all riders on a specific basis – that is, each kilogram of rider mass goes up and down an incline the same whether it’s hanging on a small or large rider. However (and this is why I brought it up), if we loosely assume climbs slow large guys more than small riders because the large have to deal with additional weight rather than that they have less specific power, then it’s not properly addressing their lower power-to-weight for other non-gravity riding conditions. If a big guy can’t keep up with his little friend on climbs, chances are he can’t keep up on sudden accelerations at lower speeds either.

And if a big guy has less specific aerodynamic drag than his small friend, not only will he normally go faster on steep down hills but he will also have an advantage while cruising on the flats (on a force/kg basis). Hence we often hear big riders saying something like “I can hang with the group on the flats but the minute the road turns up I’m off the back”.

Is that being big or underpowered? That's the issue I'm trying to get to. And I know that's not a black and white issue because we could argue that a big guy is "underpowered" for climbing but is not underpowered for cruising the flats.

[gman]

At 235 lbs, I love free speed...the climbs suck though.

[Elefantino]

As a Newtonian cyclist, it is my foe on climbs and my friend on downhills.

It works out about even.

http://www.discipleblog.com/wp-content/uploads/2008/10/sir_isaac_newton.jpg

[RPS]

Sign me up for the long straight downhill coasting tt anyday. :rolleyes:Not sure if they still have it, but years ago they had a "not-so-straight" downhill race in Maui from the top of the volcano -- about 10,000 feet drop in about +/- 40 miles. Big guys did really well. ;)

[allegretto]

you are confusing Weight with Mass.

the ratio on climbing is strength/Mass. it has NOTHING and i mean NOTHING to do with Gravity. the Force of gravity is EXACTLY the same for ALL riders regardless of Mass. period. here or on the moon or anywhere else in the known Universe unless your velocity approaches, very nearly, the speed of light, which is unlikely on a bicycle.

descending is more about frontal area vs. velocity. again, G is the same for ALL riders.

there really is nothing else to say from a standpoint of Physics.

[Clydesdale]

The article suggests that the difference in workload generally makes it impossible for big cyclists to hang with the climbers on hills. "Underpowered" might be generally true but power is only a part of climbing. It also has to do with the inhuman vo2 max it would take to keep 200 pounds moving uphill at the same rate as 140 pounds. Maybe the difference is not enough to separate the riders on the flats?

RPS - That's my kind of race! Hopefully with bar-b-que at the bottom.

[RPS]

you are confusing Weight with Mass.Who is this post directed at? :confused:

If me, I could answer. However, without reference I'm not sure who you think is confused? Would also help to know your background.

[allegretto]

yes, and we must consider two types of "strength"

1) is peak, or instantaneous. you can squat far more than a 140 lbs "weakling"

so why can't you climb better?

2) RMS strength. in other words, you cannot maintain your strength advantage for very long. more properly this would be power/weight ratio.

thus, eventually fall behind...

[allegretto]

Who is this post directed at? :confused:

If me, I could answer. However, without reference I'm not sure who you think is confused? Would also help to know your background.

anyoe who thinks that G favors anyone.

background? Chem/Physics

[false_Aest]

anyoe who thinks that G favors anyone.

background? Chem/Physics

Why come big dudes go downhill faster than this skinny ass ground hugger?

[Lifelover]

I agree with allegretto, I assume you are confusing weight, mass and impact of gravity.

When Climbing weight means EVERYTHING.

Go here and play with the numbers.

http://www.analyticcycling.com/ForcesPower_Page.html

2 riders both climbing 7% grade at 9 mph, all other things equal.

A 165 lb rider is producing 227.5 Watts

A 250 lb rider is producing 337.8 watts

That is HUGE! 50% more work!

Another way to look at it.

Same 7% grade all other things equal
a 250 lb rider going 6.25 mph is doing the same work as a 165 lb rider going 9 mph

Another way to look at it.

both at 9 mph all other things equal
A 250 lb rider going up a 4.5 % grade is doing as much work as a 165 lb rider going up a 7% grade.

Clearly you get the opposite impact descending. However the force of air pressure is exponential. Assume the Fatty (me) also has a larger frontal area, their free fall top speed would not be as high as you might think.

I think the website I linked has those calculations as well.

If you question those numbers than you can find some mountains and climb them on a fully loaded touring bike. That is what us fat guys deal with every time we climb.

[zott28]

The only time I pass my friend is down hill. He is 140 I'm 190. He always says I go fast cause I'm bigger. I think I take better lines and am a bit ballsier than he is, but I thought that weight was a factor too.

[Louis]

the Force of gravity is EXACTLY the same for ALL riders regardless of Mass. period.

F = ma

The acceleration due to gravity is the same for all riders. The force is different since we all have different mass.

[allegretto]

F = ma

The acceleration due to gravity is the same for all riders. The force is different since we all have different mass.


yes, we agree! i should have said that the ratio is the same, not the actual force.

there, all better.

[allegretto]

Why come big dudes go downhill faster than this skinny ass ground hugger?

Let’s look at an object going downhill;


We’ll assume that no pedaling is occurring and the decent is not too steep, sort of what one would encounter here on Earth.

There is the Force of Gravity pushing you down the hill, which in this case is the same as a falling object,

F=ma. In this case, a=G (which is NOT a constant, but close enough to ignore the effects)

So we can see that the F must be greater if the m is greater, since G is near-constant.

Now, what F is resisting the rider?

The most obvious is air resistance. Which as you all know is a function of frontal area. So why do heavier objects fall faster than lighter ones in air? Because of the ratio of the weight (mG) to the air. So a heavier object with a greater mass requires more air resistance to slow it down proportionally.

See; http://www.glenbrook.k12.il.us/gbssci/Phys/Class/newtlaws/u2l3e.html

The second Force is friction, which likewise bears a non-(linear) proportional relationship to the downhill mass. This is the phenomena that a lighter car will pull higher G’s on a skidpad than an exactly the same, but more massive vehicle in the same situation.

If there is no wind resistance or friction, both riders (the lighter and the heavier) would descend exactly the same.

But in the real world…

[choke]

I think aerodynamics have a bigger bearing on descending than weight. I've learned to make myself very small on a downhill and I can out coast (no pedaling) heavier riders because of that. I weigh around 165lbs, give or take.

Several years ago I used to do a cross state ride in MO, similar to RAGBRAI. I would always coast as far up the next hill as I could and only start to pedal again when my speed was close to what I figured I would climb at. On more than one occasion I coasted past people that couldn't make the climb and were pushing their bikes up the hill. I can't imagine how demoralizing it had to be to see someone coast uphill past you.

[link]

Who is this post directed at? :confused:

If me, I could answer. However, without reference I'm not sure who you think is confused? Would also help to know your background.

me ...for one. I mistook the thread's true meaning

[RPS]

anyoe who thinks that G favors anyone.

background? Chem/PhysicsThanks, I now know it’s not me.

As an engineer I know the differences quite well. Mass and weight are obviously not the same. They are not interchangeable, have different units, and have completely different meanings.

However, as a project manager who had to communicate with numerous people of different backgrounds at a technical level that they could understand (often at the same time), I’d ask you what difference does it really make in the context of this thread as used in most posts above?

Since we “almost always” ride our bikes on planet Earth, and ride “almost always” near the surface of the planet, then what’s the big deal (in the context of this thread)? Maybe I’m missing something but if we are talking about a rider whose mass is 60 KG versus the same rider weighing 132 pounds, does it make much difference to the average guy that reads this forum that one is mass and the other weight? I can’t see how.

Granted if we weighed the same 60 KG rider on the moon he’d weigh a lot less than 132 pounds, but as long as we are discussing cycling (which implies riding on planet Earth to most people), then IMO it won’t make much of a difference if someone actually confuses mass and weight.

Technically there is a big difference. Practically to most readers there is very little, and IMHO not differentiating doesn’t confuse the subject matter much at all as long as the discussion remains focused on “steady-state” climbing and descending (which I highly recommend since transient analysis would be way too complicated for most to follow).

[RPS]

A 165 lb rider is producing 227.5 Watts

A 250 lb rider is producing 337.8 watts

That is HUGE! 50% more work!
If we want exactness (not that I’m pushing for being nitpicky), watts is a measure of power and not work.

My point is that everyone knows what you meant even though not “technically” correct, just like with mass and weight. I don’t see the need to be so exact about words……unless they are outright wrong and/or misleading.

[allegretto]

Thanks, I now know it’s not me.

As an engineer I know the differences quite well. Mass and weight are obviously not the same. They are not interchangeable, have different units, and have completely different meanings.

However, as a project manager who had to communicate with numerous people of different backgrounds at a technical level that they could understand (often at the same time), I’d ask you what difference does it really make in the context of this thread as used in most posts above?

Since we “almost always” ride our bikes on planet Earth, and ride “almost always” near the surface of the planet, then what’s the big deal (in the context of this thread)? Maybe I’m missing something but if we are talking about a rider whose mass is 60 KG versus the same rider weighing 132 pounds, does it make much difference to the average guy that reads this forum that one is mass and the other weight? I can’t see how.

Granted if we weighed the same 60 KG rider on the moon he’d weigh a lot less than 132 pounds, but as long as we are discussing cycling (which implies riding on planet Earth to most people), then IMO it won’t make much of a difference if someone actually confuses mass and weight.

Technically there is a big difference. Practically to most readers there is very little, and IMHO not differentiating doesn’t confuse the subject matter much at all as long as the discussion remains focused on “steady-state” climbing and descending (which I highly recommend since transient analysis would be way too complicated for most to follow).

i would agree with almost all of what you say. and, the transient Physics, with the necessary mathematical mechanics would be unnecessarily complex.

however, the seminal question and title of the thread asks if "gravity" is the issue. clearly the true issue is mass or its proxy in this example, weight.

so i guess the ideal respone is the "neutral" one!

[Lifelover]

Gravity: Friend, foe, or neutral?



I’d like to hear different opinions on how we should assign significance to “gravity” when discussing its effect on riders of different sizes; particularly as it relates to climbing and descending.


Blah, blah, blah, blah, blahBlah, blah, blah, blah, blahBlah, blah, blah, blah, blah, blah, blah, blah, blah,Blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah?

The general idea often expressed by cyclists is that gravity is kind to small riders on climbs and kind to large riders on the descend. Blah, blah, blah, blah, blahBlah, blah, blah, blah,? Blah, blah, blah, blah, blahBlah, blah, blah, blah? Blah,Blah, blah, blah, blah, blahBlah, blah, blah, blah,blah, blah, blah, blah? Not that that’s always the case anyway -- I’ve been passed on climbs by larger riders many times.

Likewise, when large guys fly down a steep descend faster than their small buddies, Blah, blah, blah, blah, blahBlah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah, blah,? Why thank gravity instead of favorable aerodynamics?

I know its semantics for the most part, but blah, blah, blah, blah, blahBlah, blah, blah,Blah, blah, blah, blah, blah, blah, blah,blah,? Blah, blah, blah, blah, blah, blah, blah,?

I feel like I'm talking to my wife.

Was there a single question that you wanted to address?

[Ti Designs]

Step away from the physics books and get your ass back on a bike if you want to know the real story.

Skinny guys can draft the bigger guys down the hills - a fat ass punches a big hole in the wind and drafting is the great equalizer when it comes to high speeds. It doesn't work the other way around...

[RPS]

Let’s look at an object going downhill;


We’ll assume that no pedaling is occurring and the decent is not too steep, sort of what one would encounter here on Earth.

There is the Force of Gravity pushing you down the hill, which in this case is the same as a falling object,

F=ma. In this case, a=G (which is NOT a constant, but close enough to ignore the effects)In the cycling case you described above acceleration is not G.

It would be if the object was falling straight down like in the example of the elephant (link you attached), but when it's a bike on a "not too steep" road, acceleration is much lower. For instance, if the road was at 10%, the rider would accelerate down the hill much slower than if the road was at 20%.

[allegretto]

If we want exactness (not that I’m pushing for being nitpicky), watts is a measure of power and not work.

My point is that everyone knows what you meant even though not “technically” correct, just like with mass and weight. I don’t see the need to be so exact about words……unless they are outright wrong and/or misleading.

oh c'mon, you're an engineer. your raison d'ete is to be nitpicky ;)

[RPS]

however, the seminal question and title of the thread asks if "gravity" is the issue.You are right.

I used the word "gravity" because that's the one that most big and heavy guys use to explain why they can't climb. The idea for the thread came from reading a post a couple of days ago that seemed to repeat the same theme again.

[allegretto]

In the cycling case you described above acceleration is not G.

It would be if the object was falling straight down like in the example of the elephant (link you attached), but when it's a bike on a "not too steep" road, acceleration is much lower. For instance, if the road was at 10%, the rider would accelerate down the hill much slower than if the road was at 20%.

true dat. however the only motivating F is G if there is no wind. agreed the vertical vector is the only element of that G. so assuming both riders are on the same grade, that vector of G is same for both.

Force is only a "push". it says nothing about motion (a common misconception).

you do agree...?

[Lifelover]

This thread is useless without Diff Equs

[allegretto]

This thread is useless without Diff Equs


here we go...

[Louis]

This thread is useless without Diff Equs

I suggest that we concentrate our efforts on finding the gravity waves.

[WadePatton]

so, are you ready for another angle?

assuming real descents-with curves and humps/flat sections-how about _inertia_ being the pal of the heavy rider? may inertia be giving the more massive rider better velocity carrying capacity (or hotter brakes) through the none-straight-down sections of roadway?

flog away.

and i pass folks going dh with my superior tuck and dumb luck getting 'round the bends. :p :D

[allegretto]

so, are you ready for another angle?

assuming real descents-with curves and humps/flat sections-how about _inertia_ being the pal of the heavy rider? may inertia be giving the more massive rider better velocity carrying capacity (or hotter brakes) through the none-straight-down sections of roadway?

flog away.

and i pass folks going dh with my superior tuck and dumb luck getting 'round the bends. :p :D

the whole discussion is theoretical. i imagine in the real world most of us use brakes, take different lines/speeds through turns and the like. and of course there is the pucker factor, as in, "how fast is your speed limit?" ;)

[Volant]

...and of course there is the pucker factor, as in, "how fast is your speed limit?" ;)

Somewhere between stupid-grin exhilaration and, "Oh chit, this is gonna hurt!"

[paulandmonster]

this is a case of gravity sucks

[RPS]

me ...for one. I mistook the thread's true meaning
Hard to find true meaning when there is none. :beer:

Seriously, if there is something I was trying to discuss is the difference between “absolute” and “specific” values of power and drag – I was hoping the discussion would lead us there. This is where most mix-ups and misunderstandings occur in my opinion.

For instance, I weigh 150 pounds and can generate 300 watts when in shape, or 2 watts per pound of body weight. My wife weighs 100 pounds and can generate about 100 watts, or about 1 watt per pound of body weight. When we climb on single bikes I can pull away from her with ease even though I’m much heavier (i.e. – more massive). My extra weight (or mass) doesn’t mean anything because not only do I have more “ABSOLUTE” power than she (300 watts vs. 100 watts), I also have more “SPECIFIC” power than she does (2 watts/lb versus 1 watt/lb).

One of the reasons we enjoy riding our tandem is that it allows us to stay together even though we ride at different levels. Combined we weigh 250 pounds and can generate 400 watts (hence an average specific power of 1.6 watts per pound of total body weight). When climbing steep grades where wind drag is insignificant she slows me down about 20 percent (which isn’t that much and perfectly OK with me), but it allows her to climb about 60 percent faster than she would on her own. This tandem advantage (albeit at my expense) allows her to stay in groups that she couldn’t on her own.

In the case above I have more absolute and also more specific power than my wife, but in some cases the two do not favor the same rider – which is common and supports the myth that big guys are at a “gravitational” disadvantage on climbs. For instance, I have a friend who is about 225 pounds -- or 50 percent heavier than I am. He is much stronger and also more powerful than I (I’d guess he can generate about 400 watts which is more than my 300 watts). However, on a “specific” basis he only generates about 1.8 watts per pound of body weight which is less than my 2.0 watts/lb. On flats he can push me hard, but on hills I can consistently ride away from him. He may be more powerful than me on an absolute basis, but not for his size.

Descending steep grades is a different subject that has much less to do with absolute or specific power. Specific aerodynamic drag is the determining factor there. Unfortunately it's more complex a subject to discuss due to greater number of variables. The bottom line is that heavy riders and tandems love down hills.

[allegretto]

Hard to find true meaning when there is none. :beer:

Seriously, if there is something I was trying to discuss is the difference between “absolute” and “specific” values of power and drag – I was hoping the discussion would lead us there. This is where most mix-ups and misunderstandings occur in my opinion.

For instance, I weigh 150 pounds and can generate 300 watts when in shape, or 2 watts per pound of body weight. My wife weighs 100 pounds and can generate about 100 watts, or about 1 watt per pound of body weight. When we climb on single bikes I can pull away from her with ease even though I’m much heavier (i.e. – more massive). My extra weight (or mass) doesn’t mean anything because not only do I have more “ABSOLUTE” power than she (300 watts vs. 100 watts), I also have more “SPECIFIC” power than she does (2 watts/lb versus 1 watt/lb).

One of the reasons we enjoy riding our tandem is that it allows us to stay together even though we ride at different levels. Combined we weigh 250 pounds and can generate 400 watts (hence an average specific power of 1.6 watts per pound of total body weight). When climbing steep grades where wind drag is insignificant she slows me down about 20 percent (which isn’t that much and perfectly OK with me), but it allows her to climb about 60 percent faster than she would on her own. This tandem advantage (albeit at my expense) allows her to stay in groups that she couldn’t on her own.

In the case above I have more absolute and also more specific power than my wife, but in some cases the two do not favor the same rider – which is common and supports the myth that big guys are at a “gravitational” disadvantage on climbs. For instance, I have a friend who is about 225 pounds -- or 50 percent heavier than I am. He is much stronger and also more powerful than I (I’d guess he can generate about 400 watts which is more than my 300 watts). However, on a “specific” basis he only generates about 1.8 watts per pound of body weight which is less than my 2.0 watts/lb. On flats he can push me hard, but on hills I can consistently ride away from him. He may be more powerful than me on an absolute basis, but not for his size.

Descending steep grades is a different subject that has much less to do with absolute or specific power. Specific aerodynamic drag is the determining factor there. Unfortunately it's more complex a subject to discuss due to greater number of variables. The bottom line is that heavy riders and tandems love down hills.

as i said earlier, it's a power/wt ratio thing in the end, and especially the ability to sustain that ratio over the climb. this is where "work" and "power" are often confused. (no, i'm not directing that comment at you :D )

i am having an Ottrott build to my wife's specs. no off the rack would fit anyway, 5' 11" 35.25 inseam. i hope she takes to it as yours has!