Wheel Weight versus Rider Weight

bisoner
bisoner Posts: 171
edited March 2013 in Road buying advice
Plenty of wheel experts on here so maybe someone could help shed some light on the following:

1) Rim weight - I've seen people say a lighter rim has less rotational weight, thereby making it faster than a heavier rim, but is this really really true? I'm sure I've read conflicting scientific results on this subject but cannot locate the links of where I read it - or was I just dreaming!!!
2) Hub weight - similar to point 1. A lighter hub is better if you are weight conscious but on wheels weighing the same overall, is the heavier hub'd wheel going to be faster, i.e. the rims are lighter.
3) I've spent loads of cash losing 300-400g's off of a set of wheels but isn't the much easier route just losing a few pounds from my body. In an example where you lose the same weight in terms of bodyweight and wheel weight, would less body = more aero versus lighter wheels. I also see loads of cyclists with 2 full water bottles and sometimes they barely drink one - these are the same people that spend £500 on nice new wheels which are 200g's lighter than the old ones!!!

Maybe not simple to answer questions, but would help me in the Stan 340 v Archetype rim debate and whether I should bother with the premium of Dura Ace hubs versus Ultegra hubs. All rounded off with less cake of course!!!

Comments

  • ednino
    ednino Posts: 684
    Having time trialed many segment on STRAVA, my lighter wheels have made me faster

    I don't want to lose pounds off my body, im 60kg
  • deswahriff
    deswahriff Posts: 310
    ..concensus seems to be that weight saved on wheels is the most worthwhile you can make on the bike itself. For the wheel itself, I think the roatational mass thing is a given..imagine having to spin a brick round thats tied to a piece of string, regularly starting, stopping, slowing down and speeding up......then imagine swapping your brick for a half-brick...
    ..that's why lighter rims (and by extrapolation, tyres and even tubes) should make more difference than lighter hubs, which are not being spun.
    ..of course how much this translates into reality for the average punter is questionable, and certainly losing any excess weight yourself is most likely going to help more....
    ...me, I'm 66kg and hope to notice benefits from my new summer wheels when I eventually get them...I think for me , I'd get much more benefit saving 500g on a set of wheels over losing an extra 500g off my body weight...- my weight probably fluctuates by that much anyway during any given day...
  • foggymike
    foggymike Posts: 862
    I've never understood this loose weight/take a dump vs weight off your bike thing. If you are in the position to do so just do both and you'll be doing better than if you'd chosen either of the options alone.

    Lighter rims will help you accelerate faster but not be as strong or long lived (thinner braking track usually) as more beefy rims - always a trade off. If they are not robust enough to take a good spoke tension they can go out of true all the time too, but others will know more on that kind of thing than me. Once up to speed on the flat the weight at either rim or hub makes very little difference indeed. Obviously lighter is better for climbing wherever it is on the bike.

    Lighter hubs will make hardly any difference to your performance, but it may be worth paying more for better sealing, smoother and longer lived bearings or maybe just flashy branding or appearance if that's your thing :wink:
  • sungod
    sungod Posts: 17,533
    1-2) a lighter wheel will accelerate faster than a heavy one (assuming typical distribution of mass), it'll also decelerate faster

    the energy used on the flat is the same, you'll simply get up to speed faster, but you'll slow faster once you stop pedaling

    going uphill, you'll use more energy raising a heavier wheel, coasting downhill you'll go a smidge faster

    also, for constant weight, lighter rims/heavier hubs are better than lighter hubs/heavier rims, they'll accelerate/decelerate faster

    this ignores other considerations like strength/stiffness, a light wheel that's too floppy/delicate is not much use

    3) if you've no weight left to lose, the only other place to take it off is equipment

    there's also the bling factor to consider, absolutely nothing wrong with bling!
    my bike - faster than god's and twice as shiny
  • foggymike wrote:
    I've never understood this loose weight/take a dump vs weight off your bike thing. If you are in the position to do so just do both and you'll be doing better than if you'd chosen either of the options alone.

    Sanity at last :)
    "You really think you can burn off sugar with exercise?" downhill paul
  • poppit
    poppit Posts: 926
    There's an article about this in Cyclist magazine, seems to explain it quite well.
    Eddy Merckx EMX-3
    Dolan L'Etape
    Cougar Zero Uno
    Genesis Core 50
    Planet X TOR
  • Rod11
    Rod11 Posts: 293
    Would be interesting to know how much body weight you would have to loose to get the same advantages as loosing weight off the rims, i.e. I assume a 500g saving on wheels would be more beneficial than 500g of body weight?

    But yes, obviously if you can loose the body weight than it's a hell of a lot cheaper!
  • sungod
    sungod Posts: 17,533
    the only difference between 500g body weight and 500g rim weight is that if you take the weight off the rims you'll be able to accelerate slightly faster, but the wheels will also slow a bit faster when coasting (lower angular momentum) so unless you brake or are sprinting against others there's no net difference

    going up/down hills, or moving at constant speed, there's no difference
    my bike - faster than god's and twice as shiny
  • supermurph09
    supermurph09 Posts: 2,471
    poppit wrote:
    There's an article about this in Cyclist magazine, seems to explain it quite well.

    ^^^^^ This.
  • stueys
    stueys Posts: 1,332
    foggymike wrote:
    I've never understood this loose weight/take a dump vs weight off your bike thing. If you are in the position to do so just do both and you'll be doing better than if you'd chosen either of the options alone.

    Sanity at last :)

    +2. Can we frame this as a sticky, might stop the usual repetition...
  • passout
    passout Posts: 4,425
    Light wheels feel better/faster on longer climbs to me. I notice it much less on the flat. Tyre choice is a big part of this of course.

    Also, most people would not have a cr*p in order to save weight! I agree that it is a strange argument.
    'Happiness serves hardly any other purpose than to make unhappiness possible' Marcel Proust.
  • imposter2.0
    imposter2.0 Posts: 12,028
    passout wrote:
    Also, most people would not have a cr*p in order to save weight! I agree that it is a strange argument.

    I don't think 'having a cr@p' would actually constitute 'training advice' as such - but it does serve as an example of just how little difference weight loss actually makes.

    Obviously major weight loss helps with fitness n all that, but losing 1lb, 2lb off the bike (or yourself) will only actually get you up Mont Ventoux about 1 second faster, if that.
  • deswahriff
    deswahriff Posts: 310
    .....I suppose I could lose another couple of kg by having 6 inches lopped off my willy.....
  • bisoner
    bisoner Posts: 171
    sungod wrote:
    the only difference between 500g body weight and 500g rim weight is that if you take the weight off the rims you'll be able to accelerate slightly faster, but the wheels will also slow a bit faster when coasting (lower angular momentum) so unless you brake or are sprinting against others there's no net difference

    going up/down hills, or moving at constant speed, there's no difference

    Thanks for the response. In essence, it's all about the total weight of rider/bike in relation to power output. Of course, you can optimise both but the question was around losing weight off one or the other and the respective benefits - bottom line, they are the same.