Zoof
New Member
- Location
- Manchester
Why roadies pass us.
This is a rule of thumb summery of the dater on the net below.
Rolling resistance: 10% / 20% worst-case, narrow high-pressure tires give you least rolling resistance on modern smooth tarmac roads.
Off road, wide low-pressure tires give you least rolling resistance.
The reason is the tire is deformed across its width acting like a tank-track over a rock, so it doesn’t lose forward momentum by being bounced upwards.
Obviously this tires will need more Watts per mile to move it, but it is the better option.
Mechanical drag: Dérailleur gear system reduces the efficiency only slightly by about 2%
Internally geared hubs reduce the efficiency by 5% to 20% worst case.
Power in Watts: Your speed is directly proportional to how many Watts of power, you can constantly put out per hour.
The calculations on Watts burned, are from 50 to 100 Watts on a road bike. S Brown verifies 100 so it's a 100!
At 25km/h a racing bike burns 100 Watts on flat road no wind.
At 25km/h a sit up touring bike burns 200 Watts without panniers, on the same road.
With every seven Kg s of extra weight you need 70 extra Watts, to accelerate it and clime hills.
Aerodynamics: at approximately 12 km/h: rolling and air resistance are the same.
At higher speeds air resistance totally dominates.
Except going down hill with weight, remember the biggest riders, are always very fast down hill.
A racing bike has very light aerodynamic, tires, wheels, frame, and rider, so it cuts through the air like a knife.
A touring bike has to be more robust, With four panniers, air-resistance is at least 3 times greater than on a road bike.
Obviously this drag will limit your top speed, lowering your average speed.
The fuel to do the work: all the cells of the body need energy to do work.
The fuel used is glycogen (blood sugar) and is stored in all the cells and liver.
We start off riding with a full charge, but this is limited.
This is why football is only played for 90 mins, after that the fuel tank is empty.
At full throttle anaerobic (burning without oxygen) we only burn glycogen.
This produces Lactic Acid contributing to muscle fatigue, and must be burned up by the body during a recovery period.
The recovery period also allows the cells to use oxygen to replenish the energy used during the high intensity exercise.
Aerobically (burning with oxygen) we burn part glycogen, part fat and food tops up the tank, extending our ride time, but this capacity diminishes with age.
Hard aerobic training will allow you to go up to 82% of max without most of these side effects,
If you can stay only in this 76% aerobic band, stamina is extended for two to four hours. I
f the distance is under 40 miles on a four-pannier ride, I can go for it.
If it is over, I have to back off down to 40-50% or I burn out.
If you hit the wall hard, that’s a sudden lowing of blood sugar, lie down for two hours and just nibble, or you may die.
Sometimes I come in blistered, that’s giving the wall a nudge, two hours rest and I am OK.
Sometimes you have low sugar in the morning, that’s called “In the ditch” (1930s saying) have a good breakfast and rest.
These figures will predict that the best tour rider will be a tall, strong, wiry man.
Who is able to ride uphill at a fast pace, then save energy on the flat by not going to fast,
so enabling him to keep up a high average speed. With a 27 speed Dérailleur, triple 1.75 Marathons, and a good appetite.
What is your average speed, say over 50 miles on a flat route, a four-pannier into the Sun 3k Km, ride?
Because nobody has worked out yet the air-resistance drag, and weight factor of a touring bike with four panniers,
lugging 20 Kg, 3 water bottles, and a sleeping mat on the rear carrier.
The total energy expended most be 2 to 4 times that of a road bike, over the same distance.
Even if the average speed is less than half, “take that, all singing and dancing roadies”.
http://www.sheldonbrown.com/rinard/aero/formulas.htm
http://www.google.co.uk/search?hl=en&source=hp&q=cycle+wind+resiatance&btnG=Google+Search
http://www.google.co.uk/search?hl=en&source=hp&q=cycle+tire+drag&btnG=Google+Search
This is a rule of thumb summery of the dater on the net below.
Rolling resistance: 10% / 20% worst-case, narrow high-pressure tires give you least rolling resistance on modern smooth tarmac roads.
Off road, wide low-pressure tires give you least rolling resistance.
The reason is the tire is deformed across its width acting like a tank-track over a rock, so it doesn’t lose forward momentum by being bounced upwards.
Obviously this tires will need more Watts per mile to move it, but it is the better option.
Mechanical drag: Dérailleur gear system reduces the efficiency only slightly by about 2%
Internally geared hubs reduce the efficiency by 5% to 20% worst case.
Power in Watts: Your speed is directly proportional to how many Watts of power, you can constantly put out per hour.
The calculations on Watts burned, are from 50 to 100 Watts on a road bike. S Brown verifies 100 so it's a 100!
At 25km/h a racing bike burns 100 Watts on flat road no wind.
At 25km/h a sit up touring bike burns 200 Watts without panniers, on the same road.
With every seven Kg s of extra weight you need 70 extra Watts, to accelerate it and clime hills.
Aerodynamics: at approximately 12 km/h: rolling and air resistance are the same.
At higher speeds air resistance totally dominates.
Except going down hill with weight, remember the biggest riders, are always very fast down hill.
A racing bike has very light aerodynamic, tires, wheels, frame, and rider, so it cuts through the air like a knife.
A touring bike has to be more robust, With four panniers, air-resistance is at least 3 times greater than on a road bike.
Obviously this drag will limit your top speed, lowering your average speed.
The fuel to do the work: all the cells of the body need energy to do work.
The fuel used is glycogen (blood sugar) and is stored in all the cells and liver.
We start off riding with a full charge, but this is limited.
This is why football is only played for 90 mins, after that the fuel tank is empty.
At full throttle anaerobic (burning without oxygen) we only burn glycogen.
This produces Lactic Acid contributing to muscle fatigue, and must be burned up by the body during a recovery period.
The recovery period also allows the cells to use oxygen to replenish the energy used during the high intensity exercise.
Aerobically (burning with oxygen) we burn part glycogen, part fat and food tops up the tank, extending our ride time, but this capacity diminishes with age.
Hard aerobic training will allow you to go up to 82% of max without most of these side effects,
If you can stay only in this 76% aerobic band, stamina is extended for two to four hours. I
f the distance is under 40 miles on a four-pannier ride, I can go for it.
If it is over, I have to back off down to 40-50% or I burn out.
If you hit the wall hard, that’s a sudden lowing of blood sugar, lie down for two hours and just nibble, or you may die.
Sometimes I come in blistered, that’s giving the wall a nudge, two hours rest and I am OK.
Sometimes you have low sugar in the morning, that’s called “In the ditch” (1930s saying) have a good breakfast and rest.
These figures will predict that the best tour rider will be a tall, strong, wiry man.
Who is able to ride uphill at a fast pace, then save energy on the flat by not going to fast,
so enabling him to keep up a high average speed. With a 27 speed Dérailleur, triple 1.75 Marathons, and a good appetite.
What is your average speed, say over 50 miles on a flat route, a four-pannier into the Sun 3k Km, ride?
Because nobody has worked out yet the air-resistance drag, and weight factor of a touring bike with four panniers,
lugging 20 Kg, 3 water bottles, and a sleeping mat on the rear carrier.
The total energy expended most be 2 to 4 times that of a road bike, over the same distance.
Even if the average speed is less than half, “take that, all singing and dancing roadies”.
http://www.sheldonbrown.com/rinard/aero/formulas.htm
http://www.google.co.uk/search?hl=en&source=hp&q=cycle+wind+resiatance&btnG=Google+Search
http://www.google.co.uk/search?hl=en&source=hp&q=cycle+tire+drag&btnG=Google+Search
I would even say that for me there is a direct relationship between the slowest average speed and the most successful rides. Barring breakdowns of course. I don't tour to cover distance but to experience the areas I am passing through. A high average speed over a day would indicate that I had not encountered much of interest.
