C2W Makes You Fat

[Crankarm]

Try sprinting as hard as you can from a standing start everytime you are forced to stop at lights or traffic. Since you use a lot more energy to get going than to maintain cruising speed that should give you a decent workout so long as there are enough red lights on your commute.

So the reason there are so many RLJers is because most of these cyclists are fat lazy B4$*4£%$ !

 

[killiekosmos]

Perhaps I can help.

I'm prepared to swap your bike for my son's Apolling from Halfords. I'm sure that will help your weight problem.

When can I call round?

 

[jimboalee]

As Browser says, tow a parachute.

It increases the cross section area to motion, therefore increasing the Cd.

As an example.

The force exerted on a human body when it jumps out of an aeroplane is mass x g. This is a constant.

The body will accelerate until it reaches its 'equilibrium velocity'. Then the guy pulls the 'chute. His cross section area increases many fold, and so does his Cd in sympathy. Air density doesn't change and nor does Force ( because his mass hasn't changed and gravity hasn't changed ). So to balance the equation, Velocty reduces to a speed where he can land on the ground without breaking both his legs.

 

[DrSquirrel]

Almost a month since I picked up the Cube SL Cross Comp, which I love but it is causing a bit of a problem.

In my 2 years of commuting on the old Marin Bobcat Trail I'd reached a fine balance between the crap I snack on and the hell-for leather work-out on the way home. I lost the love handles and 2 inches off the waist after the first year and my weight was stable, and I eat chocolate.

The problem is that the Cube is such an easy ride compared to the Marin that I'm not burning the calories to the same extent, and the weight is starting to creep up.

So the question is do I cut back on the chocolate, or fit knobblies and adjust the brakes so they rub?

Rack + Panniers = resistance training.

Wear baggy clothing = resistance training.

Though it seems you're not upping your speed with the easier ride.

If you think you're that great add some bricks in for effect.

 

[marcw]

get a Raleigh Chopper, then you'll be thin and cool.

 

[Tigerbiten]

Upto around 10-15 mph, your rolling resistance is bigger than your air resistance.
Above this speed then air resistance is bigger.
Rolling resistance is a constant and doesn't vary with speed.
Air resistance goes up at the square of your speed and power need to move at speed goes up at the cube.
So if you double your speed from 15 mph to 30 mph, you'll get 4x more air resistance and need 8x more energy to move at this speed.

Luck ..........

 

[Arfcollins]

Thanks for all the advice and suggestions, which are gratefully accepted except that from Killiekosmos.

 

[Matty]

I do enjoy these threads where jimboalee attempts science.

 

[stowie]

get a Raleigh Chopper, then you'll be thin and cool.

I saw someone wheeling one of these in our high-street. And it wasn't one of the new ones, it was one of the originals with the proper gear shifter and everything.

Looked really cool, but I doubt it would be much good on a commute...

 

[GFamily]

.

Imagine a cross section area shaped tube of air between point A and point B. That volume of air has to be moved, no matter how fast or how slow the vehicle travels.

For the general cycling public, the cals used per distance is the same, fast or slow.

But the tube of air needs to be given speed to be moved out of the way. Give the air twice the speed and it takes four times the energy.

The cals used is not the same.

 

[jimboalee]

But the tube of air needs to be given speed to be moved out of the way. Give the air twice the speed and it takes four times the energy.

The cals used is not the same.

For non-professional commute and tour cyclists, cals per distance can be regarded as constant. Mine is 55 kCals per mile.
In the real world when a cyclist is out and about, exterior factors like the weather adjust calorific values such that the difference between riding at 14 mph and 15 mph becomes insignificant to the the point of the rediculous.

I don't use cals/km anyway. I've done roll-down tests and calculated my Cd. I use a kW per kmh 'road load' curve and everything else adjusts this figure.
I use the W vs duration curve ( posted many times ) to predict my Watts vs time, then back calc to get expected speed from the predicted Wattage. Four iterations gets it more or less bang on.
Temperature, wind, clothing, climbing and food stops adjusts this raw value.

I get a predicted time for a 100 Audax to within 5 minutes.

Calories are another thing. I seem to get round a 100 Audax on 20% of the calories internet calculators predict. I get round a 200 Audax on about 40% of internet predictions.
If my trip is less than 50 miles, I forget extra food.