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Rotational weight

 
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old 139




Joined: 15 May 2003
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PostPosted: Wed Nov 12, 2003 2:19 pm    Post subject: Rotational weight Reply with quote

Ok, so if I have been told that 'rotational' weight is far more important than stationary weight i.e. weight of wheels rather than frame etc then does everyone here spend more cash on getting lighter, wheels, tyres, pedals, cranks and even shoes???? Most people do seem more obsessed with overall weight of bike. Thoughts anyone?
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Daz




Joined: 15 May 2003
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Location: Hampton, London

PostPosted: Wed Nov 12, 2003 2:22 pm    Post subject: Reply with quote

one word - liposuction!
take it all off the waist and you'll go 5mph faster on the flat....FACT!
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Simon_B




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PostPosted: Wed Nov 12, 2003 2:27 pm    Post subject: Reply with quote

darn it Daz, you beat me to it, I was going to say lay off the bacon butties and you'll go faster...

I think Rotational weight only has impact on acceleration and hill climbing, but this is minimal impact...
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Simon_B




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PostPosted: Wed Nov 12, 2003 2:29 pm    Post subject: Reply with quote

Nice little article on the very subject...

http://www.rickdenney.com/october_1999.htm
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ed_m




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PostPosted: Wed Nov 12, 2003 2:32 pm    Post subject: Reply with quote

the deal is this:
when you accelerate your bike you have to accelerate the whole mass* of the thing plus your own mass... but you also have to get the inertia (like mass but it goes round & round) of the wheels spinning.

so if you get yourself a light (less mass) set of wheels, they're likely also to have less inertia. Giving you a double benefit as its less effort to accelerate them round as well as less mass to accelerate forwards.

whilst a light wheel will generally also have less inertia than a heavy one, it ain't necesarily so. Basically the more more mass** the further from the centre of rotation*** the more inertia. So light tubes & tyres will also help here, whilst a heavy/light hub probably won't make alot of difference.

if you care _that_ much analyticalcycling.com explains it too & gives an experiment to work out your wheel's inertia!

ed


*if you don't know what mass is: for mass read weight, not entirely true but hey.

**read 'stuff'

***read 'axle'
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Daz




Joined: 15 May 2003
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Location: Hampton, London

PostPosted: Wed Nov 12, 2003 2:39 pm    Post subject: Reply with quote

think generally the more weight you can take off the body and bike the better, esp when going up hills like chief said....thats when you really feel it. as far as wheels are concerned, you'll get better benefits (if we're talking standard wheels and not carbon vs steel!!!) from overall aerodynamics rather than rolling weight. little additions like aero-spokes, deep-rims (like the ones i am trying to sell on another thread <blatant plug> Twisted Evil ), blades and carbon will do the trick.

But best savings in weight can be on the body. A friend told me they knew someione who weighed 16 stone and was out buying expensive aero gear (both carbon and titanium) to "save secs in races from weight". now that's a classic!
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Robert




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PostPosted: Wed Nov 12, 2003 2:49 pm    Post subject: Reply with quote

All of the above - less mass, less friction, less profile equals more momentum, more speed, less effort to haul that fat arse over the hills!
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Daz




Joined: 15 May 2003
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PostPosted: Wed Nov 12, 2003 2:52 pm    Post subject: Reply with quote

rob, it must have hurt for you to agree with me for once Very Happy
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Robert




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PostPosted: Wed Nov 12, 2003 2:55 pm    Post subject: Reply with quote

Only coz you got to reply first - I distinctly remember us having a disagreement about this in the past. Obviously, my persuasive arguments must have sunk in.... Razz Wink
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old 139




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PostPosted: Wed Nov 12, 2003 3:00 pm    Post subject: Reply with quote

Thanks CC, I've printed that for a chilled read later. Right now gotta do some work, or I won't be able to afford a light or aerodynamic bike, let alone the pies to power it! Another thing - what does everyone feed themselves on pre-race, out of interest? I do a huge plate of fried potatoes!
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Daz




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PostPosted: Wed Nov 12, 2003 3:00 pm    Post subject: Reply with quote

Laughing Laughing I've said this all along you lyign git!

You disagreed with me cos you thought your extra weight (over mine)would make no difference to our cycling performances in tri's.........and we know the outcome of that! Laughing
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Sue




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PostPosted: Wed Nov 12, 2003 3:12 pm    Post subject: Reply with quote

Hi LOpezzz Smile -another newbie since I've been away,
depends what the race is for me Confused
For longer training and races such as marathons I eat spuds but done in their jackets not fried Shocked or pasta and then take raisins to bed Embarassed In the morning I eat bananas, teacakes, more raisins and sports drink --if havent time then the teacake goes to bed as well Shocked Also have jelly beans around Rolling Eyes
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Simon_B




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Location: Bexleyheath !

PostPosted: Wed Nov 12, 2003 3:22 pm    Post subject: Reply with quote

Find porridge, cut with jam is my fuel of choice before running, at least in the morning...
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