Another little gem
- Thread starter jimboalee
- Start date
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It is a little 'quick calculator' I heared about many years ago. It was for adjusting a cyclist's eating requirements for hills.
I put it to test. Calorific requirement DOES increase by approximately the multiples of the power requirement. That's logical. It appeared calorific requirement per mile increased for 5% increments by following the three time table.
5% - 3 x cals /mile
10% - 6 x cals / mile
15% - 9 x cals / mile
20% - 12 x cals / mile
25% - 15 x cals /mile
30% - 18 x cals /mile
The amazing thing was – Calorific requirement to climb a 10% gradient is multiplied by SIX. That was a shock.
So if riding along at 15 mph on the flat through still air requires 40 cals per mile, climbing up a 10% at 5 mph is burning the calories at a rate of 240 cals per mile.
When you get over the hill and are freewheeling down the other side at 30 mph, you are using 3 cals per mile.
Ride up a 10% for 1 mile = 240 cals. Ride down the other side for 1 mile = 3 cals.
Even if you freewheel for 1 mile on a following flat, 250 / 3 = 83 cals / mile, which is DOUBLE the equivalent flat 3 miles.
Now it takes a lot a working out to subdivide an entire ride up into elements of distance and their respective gradient.
I did this for 100 km of Cornwall, and found the amount of freewheeling after a hill descent counteracted the energy it took to climb to the elevation. The hills were nothing like 10%.
Climbing a 2% gradient steadily at 60% speed ( 10 mph in this instance ) was only 70% extra energy consumption.
If the 3 miles was up and down a 2% hill, followed by some pedalling and freewheeling along a flat road, the increase due to the hill was within the bounds of negligible, and easily supplied at the food stops.
An accurate sum of energy required for any ride you wish to participate on is best evaluated by doing a topographical analysis of the whole route.
Most rides I have been on, particularly in the nineties when computing power became sufficient to do the analysis within a lunch time, I found no significant increase in feeding requirement for the amount of climbing along the route. Most rides had zero AUK Altitude Award points.
Discuss.
I put it to test. Calorific requirement DOES increase by approximately the multiples of the power requirement. That's logical. It appeared calorific requirement per mile increased for 5% increments by following the three time table.
5% - 3 x cals /mile
10% - 6 x cals / mile
15% - 9 x cals / mile
20% - 12 x cals / mile
25% - 15 x cals /mile
30% - 18 x cals /mile
The amazing thing was – Calorific requirement to climb a 10% gradient is multiplied by SIX. That was a shock.
So if riding along at 15 mph on the flat through still air requires 40 cals per mile, climbing up a 10% at 5 mph is burning the calories at a rate of 240 cals per mile.
When you get over the hill and are freewheeling down the other side at 30 mph, you are using 3 cals per mile.
Ride up a 10% for 1 mile = 240 cals. Ride down the other side for 1 mile = 3 cals.
Even if you freewheel for 1 mile on a following flat, 250 / 3 = 83 cals / mile, which is DOUBLE the equivalent flat 3 miles.
Now it takes a lot a working out to subdivide an entire ride up into elements of distance and their respective gradient.
I did this for 100 km of Cornwall, and found the amount of freewheeling after a hill descent counteracted the energy it took to climb to the elevation. The hills were nothing like 10%.
Climbing a 2% gradient steadily at 60% speed ( 10 mph in this instance ) was only 70% extra energy consumption.
If the 3 miles was up and down a 2% hill, followed by some pedalling and freewheeling along a flat road, the increase due to the hill was within the bounds of negligible, and easily supplied at the food stops.
An accurate sum of energy required for any ride you wish to participate on is best evaluated by doing a topographical analysis of the whole route.
Most rides I have been on, particularly in the nineties when computing power became sufficient to do the analysis within a lunch time, I found no significant increase in feeding requirement for the amount of climbing along the route. Most rides had zero AUK Altitude Award points.
Discuss.
jimboalee said:How many would believe this?
Climbing a 10% hill, speed is reduced by two thirds and power requirement DOUBLES!
If you increase the power output, then how can you compare the speed on the hill with the speed on the flat?
Surely you need a constant power output....
Also, surely you speed would exponentially slow down, as maintaining an constant speed while climbing is effectively accelerating due to the constantly increasing force or gravity. So this means that you should say "climbing a 10% hill, speed is reduced for X amount of miles by two thirds"
Joe24
More serious cyclist than Bonj
- Location
- Nottingham
**** me
This one always causes a stir in a group of cyclists.
I checked out the 'old boys' myth with PowerCalc from the CTC website.
If you use the details for 'Tourist' and enter 24 kmh, no hill and no wind; and then enter 8 kmh, 10% hill and no wind, the result is pretty damned close to this myth.
Change the 'cruising on the flat' speed up or down from 24 kmh and the result for the hill swings away.
Grain of truth, but NOT concrete.
I checked out the 'old boys' myth with PowerCalc from the CTC website.
If you use the details for 'Tourist' and enter 24 kmh, no hill and no wind; and then enter 8 kmh, 10% hill and no wind, the result is pretty damned close to this myth.
Change the 'cruising on the flat' speed up or down from 24 kmh and the result for the hill swings away.
Grain of truth, but NOT concrete.
