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PostPosted: Wed Jun 25, 2014 10:54 pm 
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Joined: Wed Jan 12, 2005 6:04 am
Posts: 442
Location: USA
It's the sum of the surges, whether on the flats or climbs, that take their toll with heavier 25lb bikes vs 15lb bikes.

An interesting note; back when Campagnolo came out with their Vento deep aluminum wheels I bought a set soon after. If I recall the rear wheel alone was over 1500 grs. I put those on my Somec steel frame and I am certain the bike was over 25 lbs. Yet because it was somewhat of a level playing field I flew with this setup! It continually comes up with my old school friends that back then you put together a good Italian frame with your favorite group and you rode. Wasn't a lot of concern about weight.

Now days it makes sense to go light, within reason. I do not think +/- 200 grams of non-rotational mass makes much difference.


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PostPosted: Thu Jun 26, 2014 5:22 am 
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Good read guys. I still want to setup a master or de rosa slx frame with for tempo and training, and keep the race bikes tuned for racing and hard training efforts. Thing I can't decide about the retro frame is whether to go full retro with all the parts, or use a new campy groupset, modern stem, etc. The quill stem and old SR looks so sexy so probably go that way. It will be a tank compared to my s-works bikes.


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Posted: Thu Jun 26, 2014 5:22 am 


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PostPosted: Thu Jun 26, 2014 9:03 am 
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Train like you fight!

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PostPosted: Thu Jun 26, 2014 1:18 pm 
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Location: UK - Hertfordshire
I ride to work on my Canyon which is uber light, but I am actually faster over hilly sections (up down up down but not crazy steep) when I have a heavier bag on my back as you carry more momentum once moving. A very light bike is great on steep long/ or just long climbs, but you do need to put in work to carry momentum (at least I find).

I would like a heavier old heap for commuting to help strength, as when you ride the lighter bike you would be much faster after being used to riding something heavy.

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PostPosted: Thu Jun 26, 2014 5:51 pm 
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Location: USA
That's one thing I think we can all agree on. Carrying momentum with a heavy bike up short rollers is something I took for granted. I was really surprised to find that I needed to pedal my new light bike up these same rollers, or I was going to go backwards fast!


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PostPosted: Thu Jun 26, 2014 6:20 pm 
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Lewis, try wearing a big billowy windbreaker, zipped only 1/4 of the way. That would be more effective than extra weight.

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PostPosted: Sun Jun 29, 2014 12:44 pm 
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Joined: Sat Nov 20, 2010 6:06 am
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Location: Perth, Western Australia
Do you feel a massive difference in your bike between setting out with 2 full water bottles (750ml x 2 = 1500g) and the ride feel when they are empty?
This is the approx weight difference between my light and heavy bike.
I tend to think I feel a difference on long climbs as there is a 600g difference in wheels and a total if 1.5kg difference in total weight but in general riding I don't feel much of a difference.


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PostPosted: Sun Jun 29, 2014 1:22 pm 
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Joined: Mon Jul 26, 2004 8:57 pm
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Location: Ireland
Ozrider, since 600gms of that weight is rotatonal (wheels) you cant multiply that by 2 (1200gms) and the remainder of the 1500gms is static (900gms). In effect it' equates to 2100gms(2.1kgs) difference if the weight was static which is a significant amount considering upper end bikes are circa 7kgs


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PostPosted: Sun Jun 29, 2014 3:13 pm 
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Irish wrote:
Ozrider, since 600gms of that weight is rotatonal (wheels) you cant multiply that by 2 (1200gms) and the remainder of the 1500gms is static (900gms). In effect it' equates to 2100gms(2.1kgs) difference if the weight was static which is a significant amount considering upper end bikes are circa 7kgs
Utter nonsense. Difference betwen rotational and static weeight is not double. Indeed, again people make the amazing misstake imagining much greater acceleration than really is happening. The difference between static and rotational weght is minor. It would be nice if we as Weight weenies would actually use the facts instead of believing in fairtytales.

To destroy this myth:

http://en.wikipedia.org/wiki/Bicycle_pe ... ght_wheels

viewtopic.php?f=3&t=6394&p=60824&hilit=runge+kutta#p60824

/end of myth. :smartass:


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PostPosted: Sun Jun 29, 2014 11:54 pm 
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Yes. I think as Weight Weenies. Less is Best.

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PostPosted: Mon Jun 30, 2014 12:45 am 
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Location: by Crystal Springs (Sawyer Creek Trail)
I have a 10 lb difference between my heaviest road bike and my lightest. Yes I can totally feel the difference :)


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PostPosted: Mon Jun 30, 2014 6:37 am 
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Joined: Mon Feb 11, 2013 11:43 am
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I just finished putting together my heavy bike weighs about 19.5 lbs. I just climbed the biggest local climb in my area it's an avg 10 percent grade for about 2 miles. It's all I got to just go up it. There is a little flat near the beginning so most of the time it's 12 percent. It's about 200-220 watts minimum just to keep bike moving at my weight 180lbs. So I got the power data and ill do the same climb on my light bike which weighs 15 lbs and I'll leave the seat bag and water bottle at the bottom of the climb so it should be a good 5-6lb difference so it will be interesting to see data. I really prefer my steel bike but I am a slower rider than all my buddies so feel feel any advantages when it comes to equipment should be in my corner not theirs.

Here's a pic of the heavy bike
Image


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PostPosted: Tue Jul 01, 2014 3:28 am 
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Joined: Wed Feb 19, 2014 6:13 am
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Irish wrote:


The section of this article that specifically discusses the "advantage" of weight savings at wheel vs total bike is a gigantic paragraph without a single citation save for the opening sentence.

There is no doubt that the rotational component of a bike's weight has more effect than the "static" component in the overall picture.
Further, that the lighter bicycle is faster, even if insignificantly so in the real world. Therefore, simply asking if the heavier bike feels slower is a gross simplification of what's really going on...

This thread, however, is about perception - and at the very least, from the perspective of a placebo effect, the lighter bike is probably faster for most people. Just as it is shockingly easy to go set new PRs on your new bike, given the "new bike excitement"

Objectively speaking, the correct answer to the question is that the more aerodynamic bike is faster... But subjectively, I'm sure for many people the lighter bike is faster.

There was a similar thread where someone posited that their 202 wheelset was much faster on the bike than 404. We know with some degree of certainty that this is false except in extreme wind conditions, but that doesn't mean that for some reason it wasn't tangibly "faster" to the rider - even if what he was really feeling was the lower effort required to control the bike, e.g..


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PostPosted: Tue Jul 01, 2014 7:19 am 
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Joined: Mon Aug 04, 2008 11:09 am
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ProEvoSLTeamHighMod wrote:
There is no doubt that the rotational component of a bike's weight has more effect than the "static" component in the overall picture.
Further, that the lighter bicycle is faster, even if insignificantly so in the real world. Therefore, simply asking if the heavier bike feels slower is a gross simplification of what's really going on...


Again: your "no doubt" is based on faith, not physics. The location of the weight matters not. And now to go back to my post: I dismissed the nonsensical idea that rotational weight counts double. Are you not only arguing the math is wrong, you also argue it's twice as important? :mrgreen:

Oh and to nail that one down with Thor's hammer: The math show that when climbing wheel weight is not more important than frameweight... people here are arguing how light wheels help with the pacelining :roll:


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PostPosted: Tue Jul 01, 2014 3:22 pm 
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The modeling results are interesting, and frankly they did surprise me because I am (was ?) a believer that lighter bikes and wheels were 'better'.

But the statement that "rotational weight counts double" is not exactly a "nonsensical idea" since it actually is counted "double" in the math...even though it does not apparently end up making the bike faster.
From the analysis:
Quote:
Because there is both rotating and non-rotating mass, total mass and total inertial will not be the same. Because mass at the periphery of the wheel as twice the inertia as non-rotating weight, the total mass and inertia of a bike are:

M = Ms + Mr
I = Ms + 2Mr
Ms = Static mass
Mr = Rotating mass

Mass at the rim of the wheel has to be accelerated both linearly and rotationally.

Using only my subjective observations, I speculate about a psychological factor at work:
With a light bike and light wheels, your bike does "jump" to a slightly higher speed slightly easier (corroborated by the analysis). When you are suffering near you limit, if you briefly put out a little extra effort and don't feel much difference in speed, you think "why bother". But if you feel your bike jump to a higher speed, you think "this works, keep doing this!" So it gives an incentive to accept the extra pain that comes with the increased effort.
Admittedly, it is just a speculation about a psychological factor. But just because a factor is psychological doesn't mean it isn't "real".


Last edited by Rick on Tue Jul 01, 2014 3:32 pm, edited 1 time in total.

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Posted: Tue Jul 01, 2014 3:22 pm 


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