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flag intentbikes
Posted: Apr 23, 2024 at 10:47 Quote
The best bike in he whole of this forum! Simply beautiful
flag scar4me
Posted: Apr 24, 2024 at 11:33 Quote
not a bike..... but here's my idea for a oleo strut fork.

Theory is oleo strut with floating negative chamber. Allows position sensitive via the central metering pin.
Once shaft speeds reach peak for the orifice size it switches to 'deadblow' mode directly engaging the main air spring and the negative seal head moves up as it does.
Then as speed slows the negative sealhead returns as it fills, and main air spring returns to normal shaft displacement volume.
Rebound is fully controlled via the metering pin orifice size, so is position sensitive too allowing for control of higher air spring pressures when deep in stroke
Donor fork will be a manitou mattoc.

First scribbles...
Oleo strut with floating negatives seal head. First initial scribbles on how to do it on a manitou mezzer pro with only a few sacrificial parts. Let s see where this one goes donttrythisathome
sketch
And first rough schematic diagram..
Schematics for the gen1 oleo strut. Theory is oleo strut with floating negative chamber. Allows position sensitive via the central.metering pin. Once shaft speeds reach peak for the orifice size it switches to deadblow mode directly engaging the main air spring and the negative seal head moves up. Then as speed slows the negative sealhead returns as it fills and main air spring returns to normal shaft displacement volume. Rebound is fully controlled via the metering pin orifice size so is position sensitive too allowing for control.of higher air spring pressures when deep in stroke.
rough schematics
And got my donor parts stripped down.
Stripped down donor parts for oleo strut fork proof of concept MK1. Will be using a manitou mattoc as the donor.
parts

Time for some patience to do all the volume and nasty maths n work out the exact piston positions for best operations!
It's an orifice damper that goes in series to the air spring as soon as the flow rate restrictions provide enough resistance.

Wish me luck!!
flag mior
Mod
Posted: Apr 24, 2024 at 11:38 Quote
very curious how this will turn out keep us updated. Here is a good read if you havent already
https://www.pinkbike.com/news/interview-university-student-designs-oleo-shock-with-titanium-shaft.html
flag scar4me
Posted: Apr 24, 2024 at 11:47 Quote
mior wrote:
very curious how this will turn out keep us updated. Here is a good read if you havent already
https://www.pinkbike.com/news/interview-university-student-designs-oleo-shock-with-titanium-shaft.html
Haha, already been chatting with him.
Has had some useful inputs so far.
Is definitely going to be a bit of trial n error. Theory is great, but how it works.on practice doesn't always follow those tidy plans!

Have multiple metering pin rods ordered now, so gives me some good baseline options to work out the correct pin configuration.
flag R-M-R
Posted: Apr 24, 2024 at 14:40 Quote
scar4me wrote:
oleo strut fork

photo
flag scar4me
Posted: Apr 26, 2024 at 13:20 Quote
prototype parts nearly.ready for first assembly.
thinking ill go for non-position sensisite for first trial.
Floating oleo strut parts all laid out. Very close to a working prototype
The maths for simulating this are damn complicated, so taking some time to work through.

might end up with a bit of trial and error first with my hpx2.5 as the fluid.
3 metering pin base sizes to start from, to give a good idea of relative forces for each once ive sorted the piston mounting interface for them.
Then that should allow some reasonable judgements on the base pin size, and tapering profile.
flag scar4me
Posted: May 1, 2024 at 1:59 Quote
Minor update.... Plans have to pivot.
Mattock pro's have tapered stantions I completely missed during measuremens, so has given me a slightly more challenging job!

The whole point was that I could do it with most of my existing parts.
Prob have to flip that plan, and see about a mattoc comp CSU and air pistons to bring it back to viable build.
I'm not a machinist, and don't have easy access to turn stuff down, custom build pistons so bit of a pain!
flag R-M-R
Posted: May 1, 2024 at 12:23 Quote
scar4me,

If it was easy, everyone would do it! Salute
flag scar4me
Posted: May 1, 2024 at 12:34 Quote
R-M-R wrote:
scar4me,

If it was easy, everyone would do it! Salute

Challenges only make the success more rewarding!

I think I've actually managed to source what I need now.
Hopefully these are shortly on their way:
1* mattoc comp CSU (non tapered 30mm id stations)
2* mattoc comp air pistons

Minor detour, but getting back on track.
Glad I made my modelling formula coding for flexible inputs now!
flag R-M-R
Posted: May 1, 2024 at 12:57 Quote
Flexibility is critical to prototyping - the design process, the manufacturing, the means to achieving the goals, and sometimes even the goals themselves.
flag scar4me
Posted: May 2, 2024 at 11:04 Quote
Parts now all sourced, and on their way.

Had an attempt to size down one of my existing air pistons.
didn't turn out to shabby!
Mattock pro air piston custom turned down to fit the upper stantion diameter. Pain in the backside for xring seal and backup rings. Need to turn down the inner faces too to get the space for the seals glide ring or custom make new backup rings for supporting downsized xring profile.
Mattock pro air piston custom turned down to fit the upper stantion diameter. Pain in the backside for xring seal and backup rings. Need to turn down the inner faces too to get the space for the seals/glide ring, or custom make new backup rings for supporting downsized xring profile.
Mattoc pro irt piston measurement.

All just adds problems I can sort just using the correct comp model air piston anyways.
So will be using those.
flag mecheilaver
Posted: May 6, 2024 at 22:03 Quote
Does anyone here really wants to know how to build there own bike ,. let me know and i'll show you on a diaporama
flag downhilljohn
Posted: May 13, 2024 at 10:34 Quote
I would like to build a bike. I know how to weld chromoly, fixed my bmx that way cause I cracked it. I want to make a full squish bmx
flag ethanrevitch
Posted: May 13, 2024 at 10:41 Quote
downhilljohn wrote:
I would like to build a bike. I know how to weld chromoly, fixed my bmx that way cause I cracked it. I want to make a full squish bmx
What's the geo looking like?

 


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