You mention 1:1, a 70kg rider, with a 1:1 gear, on 622 wheels, would need to put out 98w on a 5%, and 185w on a 10% incline. That's over 2.5 per kilo for the 10% incline.
Don't those power figures need to assume a specific avg speed?!? [apologies if I missed something in your post! ]
Most of my big rides have used bottom gear ~around~ 1:1, and 10% climbs do tend to put me into the red; but I've never measured my power. I certainly like to have something lower than 1:1 for long/hilly rides.
Oh should have said, this is assuming a cadence of 60rpm which gives speed of 7.6kph.
Conversely a 30 front, 34 rear, would give 86w and 163w respectively, and a speed of 6.7kph.
I've calculated based on cadence, Sure you can grind out at 45-50rpm, in a higher gear, but it's gonna knacker your knees.
Remind me what degree you did again?
Computer systems engineering...
That kind of fits as a minimum climbing speed.
Looking back in Strava at various long rides it seems most of the steep climbs I end up bottoming out somewhere just below 8kph.
I can't find anything slower than that (which isn't walking), which means below that is probably too slow [for me] to stay upright easily.
(I doubt it is due to lack of low enough gears, I see various rides with that climbing speed on the carbon bike at ~45rpm, on the fixed at ~25rpm and on a bike with almost 1:1 gears at ~60rpm.)
A lot of it comes down to what you are willing to accept as a nice cadence to ride at. 6.7kph is plenty fast enough to not be falling over, but it's a lot easier to do that speed at 90rpm, than at 60rpm, or even 45rpm.
I work out a climbing speed of just under 10 kph for 185 W at 10÷, but I used 70 kg as all-up weight so with a bike added in then 8 kph would be about right.
Importantly, it has nothing to do with gearing: you'd need to put out the same power to climb at the same rate in any gear. What will change with the gear is the force you need to apply to the pedals.
And the cadence. Doing 10kph in one gear, you may have to do 90rpm, in another gear you have to do 45rpm. If you're sustaining it for a couple of hours on a really long climb, then 90rpm is gonna be a lot easier to deal with than 45rpm. My numbers have been based on a 70kg rider, and a 10kg bike. For anyone touring or ultra-racing, a 10kg all up bike weight is never gonna happen.
Which eventually* comes down to the same action as a stair climber (without bracing yourself with your arms the limit of the force you can apply to the pedal is based on your full body weight standing on the pedal). You use your legs to raise your centre of gravity up so that you can stand on the higher pedal and put all of your weight on it until the other pedal rises to the top of the stroke, lather, rinse and repeat.
This assumes climbing out of the saddle. Sure, fine for a short climb, or a steep ramp as part of a longer climb, but on a longer climb, that's gonna hurt (see the recent GCN video of the Contador 20 minute out the saddle climb challenge).
Realistically for most of us climbing is about grinding away on the gears trying to keep the pedals turning.
The position you have on the bike will also dictate which muscles you can deploy to get you up the hill. Aerobars / triathlon position will generally use slightly different muscles to the classic hoods, or drops position. My regular slogs into the wind on the aero bars, mean these muscles are stronger than those used on the hoods, this means I'm occasionally seen slogging up a hill on the aero bars, it looks bloody stupid, but it works.
Maybe it's one of those brick vs feather things? Stands to reason that heavier riders (which I certainly qualify as) are going to be stronger, but without a corresponding increase in aerobic capacity.
Not necessarily. If you have 2 people with the same height, and the same fat percentage, but different weights, then it's fair to say the heavier rider will be stronger (assuming muscles have been built for cycling rather than say dead lifting). But, if both riders are the same height, and different weights, it's more likely that the heavier rider has a surplus of Kummerspek, rather than an abundance of muscle. All other things being equal, and assuming your typical population.
I'm 92kg, I'm 1.7m tall. I've put on a little bit of muscle, but I'm pretty certain I'm lugging around a good 25-30kg of kummerspek, rather than muscle. It's part of why I struggle so much on the hills.
As for the limits, it comes down to not being able to run a 10k at the same speed as you can run 800m. You can't sprint a marathon.
There are a whole host of physiological things going on.
* Aerobic vs anaerobic vs ATP
* Lactic thresholds
* Lactic tolerance
* O2 supply and CO2 exhaust
And then it could be one of these limits specific to one of the many organs involved (heart, lungs, leg muscles, etc).
But then having to stop because my heart rate is too high could be because my unfit leg muscles are inefficient at retrieving oxygen or glycogen from the blood, not because my heart can't beat fast enough.
This is why the hearts of pro cyclists tend to be bigger, so they are pumping a larger volume of oxygenated blood for each beat. But purely building aerobic fitness at the expense of your muscles, isn't going to help. Sure you're pumping plenty of oxygen to the muscles, but the fibres need the strength to convert that into output. Hence needing a balanced training regime.
I know that if I really cane it I can get about 184bpm out of my heart, tho not for a long period. I know I can sustain 150bpm+ for hours on end (at least 13 of them at a time). What I don't have data for is how much oxygen I can pump round with that... Still wish I could put a bit more power out tho.
It should be no real surprise that 10% climbs by bike require a good level of fitness (or an e-bike).
There aren't many sustained 10% climbs around here. There are lots of peak 10% climbs, but the overall average is usually much lower. Bar Hatch (a hill route planners send you up when they want you to suffer) is only 6% average. Even Hardknott is only an average of 13.3%!
Where is here for you? Sure there may not be many 10% climbs where you are, but in Limburg, sure quite a few. Ditto the alps. There's a lovely climb in Liechtenstein to the Village of Malbune, from Skeg, that averages 10%.
On the Otzäl SR route in Süd Tyrol the climb over the Timmelsjock pass is 5.3% average for 11.29km on the direction the SR route takes. But if you do the climb in the opposite direction, is 8.3% average, with 11% peak, over 7.4km. With the same 70kg rider, 10kg, at 60rpm, on a 1:1 gear, you're looking at 156w, sustained, for over an hour. On a 30:34, at 60 rpm for the same rider is 137w. For a slightly longer period. That still represents 2w/kg.
Incidentally, for the same rider to climb the Timmelsjock at the 10kph average needed to complete an SR, you're looking at 138w, and that only gets you about 600m of the >10000m, in the full 600km...
So a 40kg rider on a 10kg bike will require proportionally more of the work they are generating to lug themselves AND THE BIKE up the hill than an 80kg rider on a 10kg bike. (That doesn't mean the 80kg rider is automatically faster, that comes down to individuals and phyisiology.)
Which is why small riders shouldn't pay much attention to big riders saying weight doesn't matter.
Except a 40kg rider is very light. A 40kg rider with a healthy BMI would be about 1.4m tall (4'7" in old money). That's very short. <1.47m is enough to be considered a dwarf by the medical profession... A 1.47m tall person would need to be 43kg to have a BMI that is considered "healthy"...
This is why I picked 70kg for my numbers in this thread. (I've also calculated the numbers for a 60kg rider), it feels more realistic as a representative weight for a human.
J