Tim C

http://news.yahoo.com/cardboard-bicycle-change-wor...

A mechanic told me that if you use a carbon dioxide inflator that unless you drain it and re inflate you will lose pressure more rapidly. Knowing that CO2 molecules are larger than nitrogen and oxygen I find that hard to believe. Is it true?

In balancing a newly installed hydronic system, valves must be adjusted to acheive the proper flow rate in each loop. How are the water flows measured to accomplish this?

Now that: http://thecheapbikeshop.com/noparts is gone, does anyone else know another site to estimate the value of used bicycles?

I saw ads from individuals wanting to sell supposedly slightly used bikes. One is a 2008 Cannondale Adventure 4 and the other is a Giant Cypress DX. What should they be worth as used bikes?

Most road bikes have caliper brakes while most mountain bikes have V- brakes. What are the advantages of each type of brakes?

A friend recommended that when I have photographs for possible evidence, I should take the SD card and bag it as evidence. If I do that, how long should the files remain uncorrupted?

I do not know as much about digital as I do about using film. I have repeatedly read that high ISO numbers produce noise. Could someone please either describe or share an example of a photo with noise in it?

At work we have AutoCAD. On my personal computer I want load one of the free, open software programs so that I could occasionally draw a sketch, or do a simple layout. Which software would you recommend?