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2

Here is another take on "bulk". At the time I completed the tour this photo was taken on I was using a home made quilt as my sleeping "bag". The quilt is the item in the blue/gray Sea to Summit dry bag sitting on top of the Extrawheel Voyager trailer. Now the quilt is not that heavy but it is clearly quite bulky taking up a lot of space, so much space that ...


7

'Bulk' is mostly about whether all of your luggage will fit in your bags. ie is the volume of your luggage less than the capacity of your bags. So it depends on how much stuff you want to take, and how big your panniers are. Aerodynamics doesn't really matter for touring. Unless you are cycling rather fast, or it is very windy. Usually the weight of your ...


2

But to compare 24 carat gold is just not fair. Bicycles are made of hardened alloys: Aluminium alloy 6061-T6 that is commonly used in bicycles is 6 times as strong as pure annealed aluminium. Steel 1090 alloy is 80 times a strong as iron. Hardened alloys go back to medieval times. Hardened 18 carat gold is about the same strength of Steel 1090. ...


4

Trivially: yes, of course you can. You almost certainly won't be able to ride that bike, though. The problem is not the weight of the frame, it's the weight of the rider compared to the strength of the gold. Essentially you have an 80kg rider on a frame that might weigh 20kg if made of gold rather than 5kg in steel. The dominant mass is still the rider. ...


5

According to Wikipedia, Gold has an "ultimate tensile strength" of 100 MPa, while steel runs from 400 to 5000. (Carbon fiber laminate is 1600.) Gold has a specific gravity of about 19, while steel has a specific gravity of about 7.8. So it would take about 4 times as much pure gold by volume, or about 9.7 times as much gold by weight. A 15 pound steel ...


0

Interesting question, and I enjoyed the technical answers given, but... I am continuously amazed at the overemphasis placed on the weight of bikes. Yes it is important, but relative to other factors it is not that significant. Lets compare a 20# bike to a 24# bike. If your budget is $1000 for a new bike, would you choose a 20# bike with very good components ...


0

No one has really addressed the size versus pressure part of the question. Nominally different sized tires will have about the same mass of air. As the size of the tire goes up the design pressure goes down. The contact patch must support the weight of the rider. Assume bike with rider is 100 lbs on the rear wheel. At 100 psi the size of the contact ...


5

I am continuously amazed at the overemphasis placed on the weight of bikes. Yes it is important, but relative to other factors in deciding which bike to buy it is not that significant. Lets compare a 20lb bike to a 24lb bike. If your budget is $1000 for a new bike, would you choose a 20lb bike with very good components and a so-so feel/fit, or a 24lb bike ...


0

The accepted answer states drag does not scale with mass. Which is true. But drag does scale with frontal area. It is fair to assume the two frames are made of the same material therefore the larger frame has a larger frontal area. Rather than compare balloon and soccer ball of the same size a more appropriate comparison is two rocks of the same density ...


3

It's not about energy to accelerate the bike to speed, but the energy to keep it there. For bicycles the kinetic energy is a small part of the total power output of the rider (typically under 10m/s = 36km/hour and 100kg, and e=1/2 m v² = .5 * 100 * 10² = 5000J or watt-seconds. So a casual rider putting out 250W could reach 36kph in 20 seconds, assuming no ...


0

Start with optimal pressure versus weight. The minimum and maximum pressure are on the sidewall - never exceed that range. Each tire manufacture will typically provide guidelines for where in the that range based on weight and conditions. This is a chart from Michelin. In this chart looking at 700X25c going from about 174 to 128 for a difference of 46 ...



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