S40 weight disadvantage on hill climb in wind speed equivalent

[cpml123]

I have been riding S40 regularly with my church group this year, after training by myself last year as I was just too afraid to ride on the road. I am now able to keep up and go faster on downhills and flats but lag behind in hills. Part of that is just my training, no doubt. I think part of that is also the weight penalty. I started thinking about that and tried to pull the analysis together to see what the weight penalty would equate to additional wind speed.

Weight penalty = 15 lb (31 lb vs 16 lb)
On a 6 deg hill, sine(6 deg) = 0.1
Additional "pull"force due to hill = 15 x 0.1 = 1.5 lbf = 6.67N
Drag equation
F= CdA x air density x velocity squared / 2
Using CdA = 0.32 for a generic bike front area in drop position and generic Cd. Assume air density at 1.225
6.67 = 0.32 x 1.225 x V squared / 2
V squared = 34
V = 5.8 m/s = 13 mph

That tells me the 15 lb weight penalty is equivalent to 13 mph wind on a 6 deg incline hill! I know the actual calculation is more complicated than that. However, for simple approximation, does the calculation make sense? I guess I need to lose more weight!! :-(

Thanks,

Michael

 

[RojoRacing]

Or you can calculate like me which goes like this "I'm heavier thus slower and everyone knows that, sooooo if I surge into the climb and make everyone think I'm faster maybe I can fool myself into thinking I'm faster" It has been working for years.

 

[cpml123]

I will try that next time!

 

[benphyr]

@RojoRacing must be the founder of the local Optimists' club. It doesn't seem to work that often for me... and your hills are quite likely longer. But that won't stop me from continuing to try nor to continue riding a heavier bike. If I go faster then great, if not it is training.

 

[jond]

When you’re gasping for air tendons straining and staying in front remember the suffering is really only in your head Lol.

Your head space can have a much bigger impact than four kg. Power of the mind is worth 30 watts. Belief system.

Sure there is some weight penalty and the gcn guys have done the calcs and permutations. It’s bugger all. Scientific terminology.

But you’re on a cruzbike advantage cloud and you can make up time everwhere else if terrain suits.

Or better yet get stronger. All in comfort. You can learn to love hills.......

Personally I’ve always found the free speed to lull me into a false sense of security and fitness can and has suffered.

That is why a check with a power meter and heart rate monitor can offer perspective.

 

[McWheels]

V = 5.8 m/s = 13 mph

That tells me the 15 lb weight penalty is equivalent to 13 mph wind on a 6 deg incline hill! I know the actual calculation is more complicated than that. However, for simple approximation, does the calculation make sense? I guess I need to lose more weight!! :-(

I think, old chap, that what you've calulated there would be the air-resistance-limited rolling velocity were that weight to be set off downhill at that incline.

Your additional effort to counter the incline is correct, so 6.67N. Work on that as additional effort compared to moving at, say 5m/s up the hill. I'd do it now but I have to go.

 

[DavidCH]

Or you can calculate like me which goes like this "I'm heavier thus slower and everyone knows that, sooooo if I surge into the climb and make everyone think I'm faster maybe I can fool myself into thinking I'm faster" It has been working for years.

Just dont pull on the arms too hard otherwise you strain the tendons.

 

[3bs]

Again I say to you, it is easier for to lose 15 lbs off of your belly than to calculate the wind value of the additional weight of your bike going up hill. book of cruzbike 19:24

 

[McWheels]

Coming back to the numbers, I think I'm going to struggle to get this right. But we can deduce some results from the principles.

Aerodynamics are non-linear, but uphill when the rider is slower, it more closely approaches this ideal. Therefore uphill is the place to spend any excess effort on a time trial since your energy isn't spent beating the wrong end of an exponential drag curve. We can therefore conclude that your aero gain uphill is marginal, while the weight remains solidly true to Newton's 2nd and slows you down.

If there's anything you can do about the rolling or mechanical resistance, then that too will benefit you more uphill than anywhere else.

 

[BikeGary]

a 15lb Diamond Frame bike? Wow!... I've never managed to own anything that light. More like 25lbs for me, so the difference in the weight between bikes hasn't been that much of an issue.

 

[bladderhead]

I used to be tempted to really go for it on the steep downhills. These days I do not like to be gasping before I even start a climb. I do not rely on momentum to get me to the top, just low gears. Psychology and optimism do not beat COPD.

And I am in no sense a weight-weenie. The wind-equivalent of my belly is a parachute at 100mph.

 

[benphyr]

The wind-equivalent of my belly is a parachute at 100mph.

I call bull-sh17 on that one: it is an aero-belly, a piece of aerodynamic brilliance specially added by precision mixing of beverages, sipping of beverages, imbibing of beverages, tasting morsels and tasting morels, touring Holland and touring Hollandaise, reclining on the La-Z-boy and lazing on the recumbent.

 

[bladderhead]

You are right. Spoiler-alert: I have a spoiler.

 

[DocS]

I've never thought of myself as a great climber, but this weekend, I did a Century Ride (106 Miles) on Saturday and a 40 mile hilly ride on Sunday for the MS Ride the River.

I crused down the hills (not stressing much), allowing the momentum carry me up some, then started spinning and shifting as the hill required...
I was surprised to see that I was able to climb hills that many DF riders were pushing their bikes up!
I'm not saying I was fast... Some hills I climbed as slow as about 4 mph, which made it hard to keep upright, but I did it all the same!

Are you clipped in? If not I'd recommend you try... Being able to pull while pushing helps...

Blessings,
DocS

 

[cpml123]

Are you clipped in? If not I'd recommend you try... Being able to pull while pushing helps...

I am clipped in... Speedplay Frogs.

I need to work on the push pull thing because I don't want to get my shoulders and arms too tensed up.

 

[DocS]

I really work on my cadence for hills... I'm somewhere in the neighborhood of 85-95 RPM on hills (maybe slightly faster) and I have a pretty large low gear (I believe 40 tooth) on my cassette...

Blessings!
DocS

 

[bladderhead]

I have 38t ring and 42t cog. I can go slower than 4mph under control, and sometimes do. Those people probably do not have low enough gears, but they are walking at the same speed as I am riding.

 

[rx7mark]

I use a 11-49t cassette with a 42t chainring and I climb at about 5 to 5.5 mph with my preferred cadence which is in the 85 -100 RPM range when I climbing. Anything under 5 mph and I get pretty wobbly, so it depends on how much traffic and room I have.

I started with an 11-42 cassette, but could not climb any long hills over 10% grade. The new gearing lets me climb to the limits of my traction.

Mark

 

[paco1961]

My lowest is 36 x 36 and 6mph. Any slower and I need the whole lane!

 

[cpml123]

I can go uphill fine with 34-40. The problem is not fast enough... hate to see my DF friends leaving me behind in the dust.