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bike weight...stupid question.

i would imagine so... cant see it being anything else, it would be an engineering feat to make a 9.3 kg frame!

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  • the weight quoted for my beloved bike is 9.3kg .as reviewed in 220.

    this is the total bike right? wheels ,crank the lot?





  • TommiTriTommiTri Posts: 879
    yeh that should be the whole thing, I think mine comes to about 7.8 in total.
  • i cant wain to get my new mavics. my wheels are shit .new ones should save me a kilo, but im not puttin them on till my i.m.

    thats my plan anyway.
  • bennybenny Posts: 1,314
    I really think you should try them before!

    New things on race day are not a great idea!!

    Just my thought.
  • husslerhussler Posts: 237
    I wouldnt recommend waiting until the race to test your wheels!! Get out on some training rides with them, you will learn how they react whilst doing various things such as accelerating, climbing, cornering and descending as well as invaluable 'heads up' regarding side winds!



    I always train on my race wheels from mid March time so i can clock a fair few miles up on them.. Also if you dont bed the tyres in you could have a nasty surprise when your nailing it down a hill and either the tyre skips off the rim of you slide off because the grip hasnt been roughed up yet.



    Oh and my TT bike weighs 6.5kg with disc and 50mm front, and my s-works tarmac weighs 6.4kgs with front and rear 50mm carbons :) which brings total weight of rider plus bike in at 76kgs! not so good in windy conditions though as I have to tow an anchor to prevent being blown away [:D]
  • treefrogtreefrog Posts: 1,242
    What is the spec of your bikes? What size do you ride? That's an excellent overall weight for a fully fledged TT bike, I suppose you have them tricked out to the n'th degree well done!


  • "Super Member"
    thanks for the posts. very informative.

    my bike is a basic ambrosio solaro, midrange campag stuff , shit mavic wheels{the front weigh nearly 1.5kg with tyre}. total bike weight is at 9.3kg.



    i have some light weight mavics ordered, which should bring it in at 8.5.

    i was going to change to a lighter bike, but if its a case of spending 2 k to save 2.kg well, i would rather depend on my training mileage to make me faster. im not shooting for kona, and i have allready done the im nice on it, so am familiar with the bike. im attached to it i must admit.

    will a kg saved in wheel weight make much of a difference over a century ride?



    o yeah. its red, and in nice i passed ,many a cervelo with a pretender on it.



  • agent_tiagent_ti Posts: 306
    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!
  • husslerhussler Posts: 237
    Treefrog - My TT bike is full Dura Ace 7800 groupset, fast forward disc and fast forward 50mm front, CBX Carbon Pro Bars with Profile F-22 Aero bars, A full carbon 54cm frame which nearly floats away by itself..... Oh yes it is fully tricked! and everything is carbon:)

    And the S-works tarmac has a set of 50mm fast forward wheels, SRAM Red groupset, pro titanium bars, and carbon stem.

    I am always looking to make everything as light as poss, the TT bike cost me £3500 so it is at the upper end of the market to start with.... Oh and its for sale:)lol
  • bobraynerbobrayner Posts: 27
    agent_ti wrote:


    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!

    Maybe if you're accelerating and braking a lot, as you have to work twice as hard to accelerate a given weight at the rim, compared to a weight anywhere else on the bike. How much does the bike & rider combination weigh? If most of your effort is going into acceleration rather then maintaining a steady speed, then at most an extra 1kg could make you work 2-3% harder.



    That percentage is going to be much smaller at a steady speed. Why would it make such a difference? The increase in "rolling resistance" caused by an extra kg anywhere on the bike is going to be dwarfed by aerodynamic effects.

  • agent_tiagent_ti Posts: 306
    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, so the wheel moves around faster, so you move faster. Because its always rotating, any difference in weight will be noticeable, which is why wheels are always the first thing you should upgrade on a bike.



    Think I've got most of the physics right there! Sure anyone can correct me, been a while since I did my A-levels...
  • garyrobertsgaryroberts Posts: 869
    My bike, fully loaded is exactly 11kg. Is this heavy? and if so how much is it likely to effect my ride performance?
  • agent_tiagent_ti Posts: 306
    Bike weight overall doesn't make that much difference, unless youre climbing or accelerating. When you say fully loaded, I assume that means with 2 full bottles, and saddle bag with all the spares and clip ons? if so, that isn't too bad, my commuting bike weighs that on its own! Still a great bike that puts up with a lot of abuse. Once you have upgraded your wheels (see physics lecture above!), then basically look at cost per weight saved and chose work your way through the best components in terms of that. But remember, is it really worth spending a few hundred pounds to save half a kilo, if you then load your bike up with 2 litres, which works out to about 2kgs, (or anything up to 6 for IM), food, spares etc unless your doing some serious climbing?
  • bennybenny Posts: 1,314
    garyroberts wrote:


    My bike, fully loaded is exactly 11kg. Is this heavy? and if so how much is it likely to effect my ride performance?

    11kg, fully loaded??

    Oh my god, Gary, you lost some serious weight there!!! You should really stop posting on 'the wall', you're going downhill!!![;)]



    Seriously, I'd say bike weight fully loaded+person on it=total weight is the most important.

    All too often I pass people riding the most pimped, tuned and skinny race steeds, but I have to search for their top tube cause something bellyish is in the way of it.

    Biking is so much about training, and when you get better then the money comes into play.

    More money=better bike, but for most of us the following is even more appropriate:

    More training=better biker!



    Sofar for today's lecture [8|][8|][8|]
  • garyrobertsgaryroberts Posts: 869
    point taken!



    what's the point spending £2k on all the fancy bits if you're 5kg over weight?



    I'm gona save the money and lose a few kg to get my 'fully loaded' weight down!
  • bobraynerbobrayner Posts: 27
    agent_ti wrote:


    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.
    That makes no difference, surely...? Half the wheel is going up and half is going down, and they balance each other out, so there's no net force in this respect. If there was a net force, you'd have a perpetual-motion machine; as far as I'm aware nobody has yet built a perpetual-motion machine out of a bicycle wheel, although Zipp are working on it.

    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
    How does that work? The circular motion of the wheel is tangential to the force (which is, anyway, a pseudo-force that arises from your choice of reference frame).



    The centrifugal force does very little work because there is very little motion in this direction. If you started your ride with 700C wheels, they will probably be 700C all the way through the ride, and they'll still be 700C when you finish.
  • agent_tiagent_ti Posts: 306
    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?
  • bobraynerbobrayner Posts: 27
    agent_ti wrote:
    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?

    Lighter rims help, to the extent that they reduce the total load the tyres put on the ground. Not by much, though, because rims rarely account for much of the weight to begin with. And even then, rolling resistance only accounts for a small fraction of the work the rider has to do. That's why tri bikes tend to emphasise "low drag" rather than "low weight".



    When you're climbing, weight is more important. Lighter rims will make more of a difference there, but still not overwhelming. For most of us, it's probably easier to shed 1kg from the rider than from the bike. [:D]



    Incidentally, doesn't this gives a clue as to why slick high-pressure tyres are helpful...?

    http://en.wikipedia.org/wiki/Rolling_resistance#Primary_cause

    Some of the work done by the rider is lost to hysteresis. If the rubber can't flex as much, there's less hysteresis...

  • BopomofoBopomofo Posts: 980
    We did this a while back.... by the miracle of 'Search', I bring you: http://forum.220magazine.com/tm.asp?m=26430&mpage=1&key=physics&#26455



    ...but yeah, what bob said.
  • BARNYBARNY Posts: 157
    Your coments regarding overall bike weight are correct but you are wrong with regard to the wheels and where the weight within them should best be located.



    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.

    Amen



  • bobraynerbobrayner Posts: 27
    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
    Yes; angular momentum is conserved.

    and for a longer period of time would require much less effort to keep it going...
    Much less than it took to get the cricket ball spinning, perhaps. But that doesn't help you.

    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.
    No; angular momentum is conserved. You don't get it for free. If you have a flywheel that's already spinning (ie. a heavy rim), then maybe it'll save you some effort when you ease off; but it won't save you any more effort than it took to get the flywheel spinning in the first place. If you could get something for nothing you'd have built a perpetual motion machine.

  • BARNYBARNY Posts: 157
    yep you are of course correct.



    But the two set ups give you iether a machine that lets you get up to speed easy, or, one that assists you maintain that speed easier...



    Did any one see those spoke things in 220 a while ago? that have weights on a spring type mechanism the weight move out nearer to the rim at higher speeds and then spring back in again at lower speeds so in many ways giving the best of both worlds... not seen them since. hmm



    I'm sticking to my post! :o)

  • 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?

  • bobraynerbobrayner Posts: 27
    halfanironman wrote:


    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?

    It's possible, and it looks like a good deal, but... "it depends".



    Losing 1kg will make any hills a little easier - how hilly is the route? If there's any alternative upgrade you're thinking of which nets you more-weight-saving-for-the-money then go for that instead. Wheels are nothing special.



    Oh, and would the lighter wheels be more or less aerodynamic?



    What else would you spend your money on?



    Or spend the €600 on a bullying trainer who'll shout at you and whip you into really intense training sessions for a couple of weekends. You could lose 1kg and improve your fitness. [;)]
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