A science nerd thread.

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driftking

Wheel size expert
I considered posting this a new thread but I think not only will the replys be minimal but it would fit better into this thread.

I am considering buying a Cane creek angleset for my 07 glory 8
It runs a 67HA with 2007 66's on the front and a 1.5 HT . Due to primarily riding DH I would like to slack it out to 65.5. Now this is where I request the help of the science nerds out there. Im not rich enough to buy a new bike if it snaps and clearly using a angle set will void any warrenty on the frame (if there is any).
Can someone please tell me the excess stress applied to the headtube by slackening it by 1.5degrees?
And
What percent would this excess stress add to the possibility of snapping the HT?

cheers
 
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Bjorn

Bjorn

Likes Dirt
Hi Driftking,

My thought is that unless you are lengthening the lever (forks) no more force would be applied. The angle at which the force would be applied would be altered by only 1.5 degrees, so it is unlikely to have much effect on a DH frame like a Glory.
If I did it and it broke, I'd strip it and send it in for warranty, but probably wouldn't mention the headset.

Ciao, Bjorn.
 
flamshmizer

flamshmizer

Likes Dirt
Hey driftking, I'm only a first year engineering student but they way I see it is this.

Forkangles.png

Now the major component of the force that you are worried about is the horizontal component, otherwise you would worry about it being steeper.

So on the fork angle, the horizontal component is cos67 * X (the axle to crown length) while on the new fork angle the h component is cos65.5 * X. Cos67 = .39 and cos 65.5 = .41, so the actual difference in the forces exerted is .02%.

I know this is a massive oversimplification because it doesn't take into account the fact that the fork moves up and down, square edge bumps and doesn't actually have any forces in it at all, but it does at least give some idea as to how small the difference in force will be. Obviously this would be thrown out the window if you got a taller fork, because not only would the angle change but X would be greater.
 

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3viltoast3r

3viltoast3r

Likes Bikes and Dirt
Being a single crown your are more likely to ovalise the HT by yanking on it from the bottom cup - And if you do actually manage to break it, you can hunt a new frame..

I say go for it, will be fine.
 
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driftking

Wheel size expert
Thanks for that flamshmizer, added stress of approx 0.02% to me seems to be well worth the performace increase by slackening the HA. As you said this will not take into account movement of the forks travel.
If anyone has the time to do a calculation that includes this it would be greatly appreciated. :)
I cant imagine a freeride frame as beefy as the glory would have any trouble handling the slacker HA but to use a cliche, better to be safe than sorry.
 
flamshmizer

flamshmizer

Likes Dirt
driftking said:
Thanks for that flamshmizer, added stress of approx 0.02% to me seems to be well worth the performace increase by slackening the HA. As you said this will not take into account movement of the forks travel.
If anyone has the time to do a calculation that includes this it would be greatly appreciated. :)
I cant imagine a freeride frame as beefy as the glory would have any trouble handling the slacker HA but to use a cliche, better to be safe than sorry.
Click to expand...
Actually its 2%, not .02%. I've been studying for exams so my brain is a little fried, my bad. But 2% stress is a parking ticket for a headtube as beefy as the glory's.
 
thecat

thecat

NSWMTB, Central Tableland MBC
flamshmizer said:
I know this is a massive oversimplification because it doesn't take into account the fact that the fork moves up and down, square edge bumps and doesn't actually have any forces in it at all, but it does at least give some idea as to how small the difference in force will be. Obviously this would be thrown out the window if you got a taller fork, because not only would the angle change but X would be greater.
Click to expand...
You'd also need to consider that the change in angle would alter the direction and placement of forces throughout the frame. I doubt it would have a major effect with such small changes but I could be wrong
 
LJohn

LJohn

Likes Dirt
I'd be more worried about the moment created at the headtube. In which case it's a 6% increase in moment. This is damped by forks to a degree though.

Even with the 2% gain in axial force, the safety margin of the frame should be WAY larger otherwise I wouldn't be riding that frame.
 
thecat

thecat

NSWMTB, Central Tableland MBC
Back to science

Solar Flare
[video=youtube;Q_3u_0NN7OM]http://www.youtube.com/watch?v=Q_3u_0NN7OM[/video]
 
Hamsta

Hamsta

Likes Bikes and Dirt
Yes, you know things are dire when you read something like this:

http://www.theonion.com/articles/suffering-blue-whales-plead-with-environmentalists,17619/


In all seriousness, one of my collegues just spent 3 weeks on a rig tow from Singapore to NW WA. He commented that the amount of rubbish he observed floating on the surface of the ocean was alarming, and he was only outside watching the Dolphins, Mahi Mahi, Flying Fish etc for a total of maybe 2 hours each day!.

I went for a surf today at a spot on the fringes of the metropolitan area and I collected enough rubbish to fill my wetsuit bucket and there was still a lot of rubbish left lying around, enough to fill my bucket again this Thursday. Makes me kind of sad:(

On a more positive note, the next time I feel cold, I will simply watch the clip of the Sun. Can feel the heat radiating from my laptop.
 
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for those about to rock

for those about to rock

Likes Dirt
I thought I'd post these here as I don't want to overcrowd the LTYL thread with photos from space. Not that thay are bad nor uninteresting, I just feel they would be appreciated more here.

First is a picture of Titan, one of Saturn's moons bisected by the rings of the planet:




And the second image is of two of Saturn's moons, Titan and Rhea:




And just because I am curious and the subject intruges me, is anyone else here into astronomy? Has anyone done any professional work or even just seen an especially cool celestial event?
 
Bermshot

Bermshot

Banned
Not especially rare but more in the manner. I was going to go up to the park to watch the full lunar eclipse from a couple of years ago. The moon rose from the SE around 7.30 and for about 1hr 1/2 I only had to turn my head to see whilst it went through the fazes in red. A couple of beers were enjoyed and I could not have paid for a better viewing place. A grand evening!
 
S

Shredden

Knows his goats
I don't know if I am going to be wording this right, but I'll give it a go -

Is the shock rate on a bike Linear?

e.g

50kg rider on a 200 pound spring
&
100kg rider on a 400 pound spring

Will the shock be the same stiffness for both? This probably belongs in the stupid questions/maths nerd thread but oh well.
 
Ivan

Ivan

Eats Squid
SillyWabbit said:
I don't know if I am going to be wording this right, but I'll give it a go - Is the shock rate on a bike Linear? e.g 50kg rider on a 200 pound spring&100kg rider on a 400 pound springWill the shock be the same stiffness for both? This probably belongs in the stupid questions/maths nerd thread but oh well.
Click to expand...
On the same bike yes, on different bikes, no.
 
for those about to rock

for those about to rock

Likes Dirt
I had about five different photos I was going to post, but in fear of it being unwanted, I culled it down to one photo and a pretty sweet video.

If you don't know what this is, your aren't nerdy enough for this thread.
Well that photo was way too big. If you still want to see it, and I would recommend it, here's the link: http://s3.amazonaws.com/ciclops_ir_2010/6542_15750_1.jpg

I could only come up with one word to sum up this video: woah!
[video=vimeo;4366695]http://vimeo.com/4366695[/video]
 
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