Homemade Parts!

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Homemade Parts!
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flag R-M-R
Posted: May 21, 2019 at 8:31 Quote
highsider, great video.

Another (and I'm sure there are others):
flag Grumposaur
Posted: May 21, 2019 at 8:43 Quote
R-M-R wrote:
Grumposaur wrote:
Say you have a 100 kg rider, lands a bit nose heavy 50% of his weight on the front. That is already 50 kg dead weight, but for sure the deceleration will be multiple g's.

True, but keep in mind a rider's arms are only so strong; the rider will collapse at a certain point and limit the maximum load.

Easton and Enve (and others, probably) have posted videos of handlebar testing procedures. Rather than trying to invent a test procedure without any experimental data, just copy what the veterans have learned and get a twenty year head start on your test design!
Agree, but if static load can already be 50kg, testing should be higher than 40kg/400N.

In the video from highsider it is a cycle of:

1200N push, 250N pull, offset impact
450N push, 250 N pull, climbing
700N push, 250Npull , XC
400N push, 500N pull, hard climbing
1150N push, 450N pull, DH
1700N push 900N pull, jump impact.

So in comparison I would say 400N is on the lower side.
flag Grumposaur
Posted: May 21, 2019 at 8:49 Quote
That ENVE video is also nice, but I prefer the way of testing from that syntace video. Once you got that machine set up you can do many test until failure. The ENVY guys have a labor intensive test and after 150 drops called it a day.
flag R-M-R
Posted: May 21, 2019 at 8:55 Quote
Grumposaur wrote:
That ENVE video is also nice, but I prefer the way of testing from that syntace video. Once you got that machine set up you can do many test until failure. The ENVY guys have a labor intensive test and after 150 drops called it a day.

Agree, but the Enve test may be easier for a high school student to incorporate into his design project!
flag Grumposaur
Posted: May 21, 2019 at 10:30 Quote
R-M-R wrote:
Grumposaur wrote:
That ENVE video is also nice, but I prefer the way of testing from that syntace video. Once you got that machine set up you can do many test until failure. The ENVY guys have a labor intensive test and after 150 drops called it a day.

Agree, but the Enve test may be easier for a high school student to incorporate into his design project!

Making a similar set-up is easier indeed. But you would still need to do some calculations, and have to know the springconstant (or measure it) of the bottom bumper to related the height, together with the handlebar weights to a the load the bar is experiencing.

Anyway those loads of syntace are very interesting Smile

This one also has some good values in there:
flag R-M-R
Posted: May 21, 2019 at 10:38 Quote
Grumposaur wrote:
Making a similar set-up is easier indeed. But you would still need to do some calculations, and have to know the springconstant (or measure it) of the bottom bumper to related the height, together with the handlebar weights to a the load the bar is experiencing.

Again, I agree, but for a high school project, I would be satisfied if the student simply calculated the energy from the ENVE (or similar) test and used that as an input.
flag Grumposaur
Posted: May 21, 2019 at 15:16 Quote
I agree and I am not trying to downtalk Jurchek's design or project. It was just the trigger to think about design a bit more and the associated loads; currently I have some time off to thing about some designing myself again. I became more a big structural steel guy and thinking of going back to more refined design work.
flag R-M-R
Posted: May 21, 2019 at 16:03 Quote
Grumposaur wrote:
I agree and I am not trying to downtalk Jurchek's design or project. It was just the trigger to think about design a bit more and the associated loads; currently I have some time off to thing about some designing myself again. I became more a big structural steel guy and thinking of going back to more refined design work.

That's reasonable.

Speaking of future projects and uncertain stresses, maybe a good project would be to create a library of stress data. Recreation riders, pro riders, heavy riders, light riders, male, female ... Strain gauges are cheap and there must exist some tiny receiver that could receive the signals and transmit it to a phone.
flag matt-15
O+
Posted: May 21, 2019 at 16:09 Quote
I have a piece of plexiglass about 1 foot by 1 1/2 feet and the tools to cut it, and wanted some ideas of what I could use it for.

I already have a chainguide on my bike so even though that would be one of the easiest projects to do, I'm not about to throw away my $150 one for a homemade part (even though it would be a cool conversation starter). I have a full suspension trail bike as well as a fully rigid gravel bike if you can think of anything I can make for them.

I've never made anything custom for any of my bikes so I thought I'd start small with a non-essential piece (I don't want to start off making a part that could end my ride if it fails)
flag Jurchek
Posted: May 26, 2019 at 12:23 Quote
Hello, today i made stress simulation with 500 Nforce (1000N combined). In real life I must say that after a few rides the stem does its job.

EDIT: I messed up simulation. Here are results for load with about 14000N on every side

photo
flag Pedro404
Posted: May 26, 2019 at 14:04 Quote
Jurchek: How much does it weigh? It looks hefty enough to not need any stress analysisSmile
flag SuperstarComponents
Posted: May 29, 2019 at 11:10 Quote
Correction you have done 500KILO Newtons per side.....

the FEA says it will fold out the top of the stem and indent the bar area at that but the bars will fail well before that.

im not surprised with 50 tons of pressure on it!!!


now the important thing is fatigue testing rather than outright load testing.

I think it will be just fine with a factor of safety or ten or in your case 100...

Neil Superstar Components

Jurchek wrote:
Hello, today i made stress simulation with 500 N force (1000 N combined). In real life I must say that after a few rides the stem does its job.

photo

photo

photo

photo
flag OneBanana
Posted: May 29, 2019 at 11:20 Quote
SuperstarComponents wrote:
Correction you have done 500KILO Newtons per side.....
A lot of Europe uses commas as decimal points (and indeed read as x comma y, rather than x point y), so yes it is possible that it's three orders of magnitude out, but also could just be that the software has been set to use this convention.
flag Grumposaur
Posted: May 29, 2019 at 12:02 Quote
OneBanana wrote:
SuperstarComponents wrote:
Correction you have done 500KILO Newtons per side.....
A lot of Europe uses commas as decimal points (and indeed read as x comma y, rather than x point y), so yes it is possible that it's three orders of magnitude out, but also could just be that the software has been set to use this convention.
Yeah it is 500N. See also the comma denominator in the MPA values.

Also with 500kN you would have had more then 800MPa.

Those deflections are hardly visible in real-life of on the stem itself with these loads.
flag Jurchek
Posted: May 30, 2019 at 11:51 Quote
Pedro404: It weights 350g without bolts.

SuperstarComponents: Today I was trying to make fatigue simulation but I think you have to own a proper version of Inventor, not just a free students version, to be able to make fatigue simulation (I didnt find certain tabs and panels that were mentioned in autodesk's web manual). I hope I am wrong tho.

I also discovered that I went full retard. I have found that I have been doing simulations with 8 diffrent forces (with sum of about 14000N) piled up. (no shit that it seemed weird to me when i was applying 200N on both ends and stress of about 800 MPa wes exscided)

Here are correct versions of simulation with load of 500N per side (1000N combined). I have also updated "handlebar" which is now basicly a pipe with wall thickness of 3,5 mm and lenght of 75 cm.

photo

photo

photo

Never go full retard.

 


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