To lighten crank or not to lighten crank

Bloody hell, now I'm completely confused ...BUT... I'm going for a lightened crank. Not for any other reason other than that's another 3 kgs of weight gone. Trying desperately to get Jenny to come in under 180 kgs dry. I'm at 190 kgs now so with a bit more fuckery and some more money in the future I may get there.

FFF
 
Put Helium in the tyres.
Use a Lithium battery.
Throw away your bodywork and get Boba to remake it in carbon.
Tubeless radials will be lighter too.

Or get a haircut and take some laxatives.
 
padlock said:
Bloody hell, now I'm completely confused ...BUT... I'm going for a lightened crank. Not for any other reason other than that's another 3 kgs of weight gone. Trying desperately to get Jenny to come in under 180 kgs dry. I'm at 190 kgs now so with a bit more fuckery and some more money in the future I may get there.

FFF
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Veeery ambitious.  I managed to pare off a good 2 kg.  Don't think much more than another 500gr. would be possible without compromising strength and re-buildability.

Easier/cheaper to save them (and more) elsewhere.

piet

piet
 
Grant said:
Put Helium in the tyres.
Click to expand...

I've noticed that helium-filled balloons self-deflate in a couple of days. My theory is that the helium molecules are small enough to filter through the inter-molecular spaces in the rubber. I'm wondering if the same thing would happen with a tyre, and if so, how long would it take for the pressure to reduce enough to cause problems.

Here's a hypothetical question to ponder. If you inject helium into the combustion mixture, would it make the exhaust note go all squeaky?
 
Wish the bloody hardly rideables that go past my place would inject some helium into their mixture >:(
 
Dellortoman said:
Here's a hypothetical question to ponder. If you inject helium into the combustion mixture, would it make the exhaust note go all squeaky?
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Cam, well since helium doesn't burn very well (actually not at all) it would probably make the exhaust note very very quiet.
An 80/20% heliox (instead of atmospheric air) mixture in the combustion chamber would probably increase the number of harmonic tones by dampening the fundamental tone of the combustion, hypothetically creating a higher frequency sound IF our nerves could transmit acoustic signals of combustion fast enough. But they can't.  ::)
So it would probably sound exactly the same, but the lower density gas might flow very differently in the cylinder head ports and combustion chamber, causing God knows what changes.  8)
So it would either not run at all, produce either more or less power, or be exactly the same.  (dunno)
I wonder if anybody has had enough time on their hands to try it and see?

Ken
 
I think its safe now to take your tongue out of your cheek ken :LOL:
 
Apparently helium supplies are running low worldwide as the bloody people keep using it to fill party balloons instead of reserving it for scientific and medical purposes.
 
Yes Ken, heliox. I wasn't suggesting that an internal combustion engine would run on 100% helium.  ::)

It's actually the expanding nitrogen rather than the fuel oxidation that powers an engine. Helium has a higher specific heat than Nitrogen, but a much lower density, so for the same cylinder volume, helium requires less energy to heat it up to the same temperature (thermal expansion is the same - universal gas law).  Therefore a heliox engine would, in theory, run more efficiently than a nitrox (air) engine.

I dunno whether anyone has ever tried it in an internal combustion engine. Probably not because it's not a practical way to run an IC engine. However, with external combustion engines, such as a Stirling engine, power output is massively increased if the operating gas is helium rather than air.

PS:
Davo. I agree that helium is wasted on party balloons. They'd be much more fun if they were filled with hydrogen  :D
 
I had an external combustion Laverda once. With total loss lubrication and positive crankcase ventilation.
 
Dellortoman said:
PS:
Davo. I agree that helium is wasted on party balloons. They'd be much more fun if they were filled with hydrogen  (bang)
Click to expand...

Fixed  :LOL:
 
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