A kilo will save a lot over a century ride if its in the wheels, as this will (assuming most of the weight comes from rims and spokes) dramatically reduce the rolling resistance of the wheels, so will make it feel a lot quicker!
My bike, fully loaded is exactly 11kg. Is this heavy? and if so how much is it likely to effect my ride performance?
If youre moving at a constant speed, then bike and rider weight will have a little effect apart from the wheels, because in effect the wheels are always changing direction, and having to work against gravity for half of their travelling.
Also because they are moving in a circle there is a centrifugal force working on them, acting as an acceleration (a=F/m), so if you reduce the mass of the rotating part, you increase the acceleration in a circular motion
Right apologies, apparently my physics is wrong, formula i need is F = (W a)/r See http://en.wikipedia.org/wiki/Rolling_resistance for details, basically less weight, less reaction force from the ground, less resistance. Still cant work out why lighter rims help, anyone got any ideas?
Imagine you have a peice of string with a tennis ball tied to the end (very light) swing this around your head in a circular motion.... quick to get up to speed..... now stop spinning it.... it stops going round quite quickly... for a short time its easy to spin it, for a longer period it gets quiet tiring. Now imagine the same experiment with a Cricket ball.... same shape and size (ish)... bit harder to get up to speed but once there it has a huge amount of energy stored up in it
and for a longer period of time would require much less effort to keep it going...
With this in mind if you know you are doing a flat course get your self some really heavy tires and put the on your race wheels.... and on a hilly course one use light race tires..... this will give you the cheapest speed boost avialble. You'll notice in tour de france the difference in wheels being used between the hills and the flat sections same thoery. So, man with ultra light TT bike - consider getting yourself some heavy tires! It will make you faster on most TT courses.
ok lads, cut to the chace for me please. im doing the i.m. austria. will i bother getting the light wheels or not? 600 euro im spending. if its not going to make much difference, id rather save my money.i will be saving a kilo weight. is it worth it?