Bike mass & componet questions
I'm new to biking brought into it when my friend lent me a bike he bought for some of its parts. I enjoy it so much that when he gets the rest of the parts he needs to assemble his new bike (one of about 10) I will replace his bike with one of my own so I can continue to ride.
I have a few very general questions and hope this is an appropriate forum as I don't see a new riders category.
1. Bike mass is clearly a huge issue. All the component catalogs I see give the mass of items for sale with a general rule that the least massive are the most expensive. Where is mass so critical? I can see that large amounts of mass differences in the reciprocating elements, such as the wheels, will make the bike accelerate and brake easier (flywheel effect), but what about overall mass? Is a 16 lb (7+ kg) bicycle with a 170 lb (77 kg) rider pretty much the same as a 26 lb bike with a 160 lb rider (assuming the reciprocating roughly the same)? Will a new fellow like me really care or feel a difference?
2. Along those lines, if I were to buy a 16 lb bike and then add 2 liters of water in frame cages would that bike ride the same as a 20+ lb bike with no water onboard?
3. The bike I'm riding has Dura Ace 'gears', brakes and cranks. My friend says they are his favorite which says to me that they are clearly top of the line - as does the prices I see in the catalogs. To my embarassment, I can't understand what they are doing for me compared to anything else which will function. The bike changes sprocket ratios, stops pretty much like any bicycle and the cranks, well, crank. When the inevitable arrives and my friend reclaims his components putting me out in the market, will I notice a one or two grade decrease in component quality?
4. Finally, is there a lot of technological change in bicycling? I figure that my best bet will be in the used market, but don't wish to buy something that's so badly dated that I would be better off buying new to get current tech. As a compare, someone new to computers will not be happy with an 8 year old computer no matter its condition. Are bikes also rapidly changing? I'm concerned that they may be at least from a materials view.
Thanks for any answers OR pointers to links where these questions are addressed.