WW hoods

Discuss light weight issues concerning road bikes & parts.
P90Puma
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by P90Puma

prendrefeu wrote:
Thu Feb 22, 2018 6:17 pm
4ibanez wrote:
Thu Feb 22, 2018 5:18 pm
Any idea if shrinking the material sheds any weight?
? Sorry, I don't understand what you are asking. Are you asking if the material depletes over time and thereby loses mass through use?

Pretty sure he's asking for a violation of the conservation of mass law :)

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prendrefeu
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by prendrefeu

HA! I re-read the question again and I see what he was asking!
And yes, that is a violation of one of the few laws we have in physics.

So no, shrinking it does not reduce mass, it only tightens the bonds within the material, increasing its density and decreasing its surface area (ie, making it smaller). In the theory if it being 2:1 the material will reduce to approximately 50% of its size without hinderence (ie, if there is nothing blocking it from reduction). When we put the heatshrink over an object that object blocks the ability of the bonds to tighten to their potential (but the bonds still do reduce where they can and the end result is smaller/tighter and more stiff compared to before)
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4ibanez
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by 4ibanez

Apparently tubs lose weight as they age and harden somewhat. Just wondered if a similar effect happens with this (different) process...but thanks for explaining!

I think final question is: are you doing this after taping the bars?

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prendrefeu
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by prendrefeu

Yes, after taping the bars. After heated the material is not very pliable, so you can't really tuck the wrap under the hoods like normal.
Also be sure to tape the bars really well because the hoods are slightly smaller than regular hoods, so you end up getting reveals of areas that normally are covered by the hoods and not bar tape. Practice will get you to where you want to be with this.

I'm still searching for a lighter material for hoods that is just as durable and easy to install for this application (3D curves are an issue!).
This has been the most durable material so far compared to other things I've tried.
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prendrefeu
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by prendrefeu

4ibanez wrote:
Thu Feb 22, 2018 6:34 pm
Apparently tubs lose weight as they age and harden somewhat.
I don't ride tubulars but I'm entirely intrigued by this, as it's the first time I've heard of such a thing.
So you're saying (or others are stating) that tubulars which have not been ridden at all, remain unchanged in glue remnants or lack thereof, but are being "aged" lose mass? WOW! :unbelievable: Is this real, measured? Or is someone just stating the feeling of it being lighter and harder?

I mean, the only things that, conceptually, lose mass on their own are liquids and radioactive materials. Liquids change to different forms (is, gasses) over time yet would still have the same mass if, theoretically, all of that converted gas can be contained in the same volume of the original liquid (at which point, probably, the gas would become a liquid again due to pressure).

Radioactive materials lose mass through various means (usually atoms actually splitting off and leaving)
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4ibanez
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by 4ibanez

Might've been something I read a year ago - maybe comple BS :noidea: I didn't really pay it much attention, as I was reading up about stretching tubs, and skimming all the other stuff. It was something to do with the ageing of non-vulcanised tubs.

Fiery
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by Fiery

Rubber can dry out with time, which would imply some mass loss through evaporation. It does strain credibility that it would make for a measurable difference in aged tubulars though.

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Gearjunkie
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by Gearjunkie

This is awesome, especially as my current Sram Red 10S hoods are close to wearing out.

So I'm going to try this.

Thanks Prend.

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4ibanez
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by 4ibanez

BTW most sellers seem to measure heatshrink by internal diameter (of the tube when round). This converter website does the calculation for you: http://www.defendacouriers.co.uk/layfla ... -diameter/

So Prendy's flat 3" = an internal tube diameter of 1.9096" or 48.5mm. Most sellers have 50.8mm/2" tube diameter. I'm guessing there are small variations in production and maybe Prendy's wasn't flat as a pancake (assuming his product was a standard inner diameter of 50.8mm).

Anyway - enough waffle... in conclusion you need a diameter of 50.8mm to get 3" when flat. Hope that's useful to someone!

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prendrefeu
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by prendrefeu

Good catch, thanks 4ibanez!
I'll update the previous post to reflect this.
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