12" front suspension ideas (linear bearing?)

[circuit]

So obviously 12" wheels are not the ones that are usually mounted on fast and well built bikes and so there are no suspension forks around.
I was going through various ideas and had this "new" one. Or at least I think it is new, because I did some research and could not find anything on the topic.

So the idea is to use a few linear bearings like this one:

One part is attached to the wheel axle (from both sides of wheel) and the other part to an existing rigid fork. What we get is an extremely smooth fork without an actual suspension, so all that remains to add is a quality air-loaded rear suspension, like this one:

The overall fork design could look something like "the springer" seen below.

Any more ideas/suggestions? Or maybe someone has already tried that?

 

[Toorbough ULL-Zeveigh]

i'm not clear on what the linear bearing brings to the table.
seems like it would be heavy & subject to racking.

is this for use with a hubmotor?
some alternatives:
perhaps you can make a headshock in steel to work
loop wheel
girder fork

 

[sigimem]

As far as I know the cannondale lefty uses a similiear system maybe you can get inspired there

 

[agniusm]

 

[circuit]

agniusm, this fork will break. Had one like this 13 years ago. It hurt quite a bit.

 

[speedmd]

Another possibility.

 

[circuit]

Just a quick sketch. Thoughts?

 

[speedmd]

The linear bearings are typically used in precision equipment and are expensive, heavy and need added support as you have drawn them used. Thinking the biggest problems in using them in suspension systems will be keeping grit out of them and keeping them lubed . Would think a round type could be easier the seal.

 

[circuit]

I've got these for $90:
http://www.ebay.co.uk/itm/281101479292?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Contamination problem could be somewhat improved with these bellows:

Round type has it's own problems: very few ball rows (weak) and heavy rods (no tubes available?). But maybe worth a try?...

 

[xadmx]

+1 what speedmd said, the bearing have rubber wipers on to keep the track clean but you only need a bit of dirt and you will have problems. and its a pain in the ass trying to clean them out, and thats if you don't lose all the balls out of them doing so

try modding something like this, easy and cheap.
http://www.ebay.com/itm/FRont-forks-suspension-Yamaha-Riva-xc200-xc180-/121169351754?pt=Motorcycles_Parts_Accessories&hash=item1c3641944a&vxp=mtr

 

[Thud]

I like these for a simple boinger:
http://www.recumbents.com/wisil/headshock/headshock.htm

 

[friendly1uk]

Why not find a big heavy set that can stand some welding, and chop them up. Everything is there that you need, and a bit more. You could farm the job out if you wanted. Such an approach would yield a professional result.

I thought the scooter idea a good approach. They can't all be badly made.

 

[circuit]

Okay, so I think I have found a solution. Cannondale Headshok.

80mm travel. It has a similar system to Lefty's, however is integrated into head tube, enabling this shock to be shortened.

 

[Toorbough ULL-Zeveigh]

gee, i already gave you that solution four days ago.
or could have found it for yourself four years ago if you simply searched the forum.
since you don't read this anyways, enjoy larnin' the hard way.

I have a Cannondale and I have a Headshok, I have a Cannondale e-bike. Guess what? The Headshok is sitting in my garage and a Surly 1x1 fork is on the e-cannondale.

Just don't do it

http://endless-sphere.com/forums/viewtopic.php?f=3&t=13620

 

[circuit]

gee, i already gave you that solution four days ago.

I'm having troubles finding your offered solution. Please point me to it. I hope I'm not asking too much of your kindness.

or could have found it for yourself four years ago if you simply searched the forum.
since you don't read this anyways, enjoy larnin' the hard way.

I have a Cannondale and I have a Headshok, I have a Cannondale e-bike. Guess what? The Headshok is sitting in my garage and a Surly 1x1 fork is on the e-cannondale.

Just don't do it

http://endless-sphere.com/forums/viewtopic.php?f=3&t=13620

Actually all those post on your link are worthless. Why? Because they are silly enough to offer steel forks over aluminum. Also they talk ONLY about elastomer Headshock, which is just not fair. Just go to any website and read reviews, mkay? It may be unreliable and hard to maintain for some, but these forks are ones of the best performing. And with 12" wheel and shortened legs, loads will be at least 30% lower during braking. I and DO need it to be as light as possible. It is for foldable ebike, which will be carried upstrais 4 floors each day TWICE. Remember?

 

[sigimem]

I like your sketch. As someone mentioned there is a problem with dirt getting in the linear bearing.

Please consider the large moment on this construction when you pull your front brake hard. It might breake the bearing and get you into a crash.

 

[circuit]

I agree on dirt problem, it looks difficult. This is why I have abandoned this project and move on to Cannondale Headchok, for now at least. It will take only like 2 hours to shorten factory fork's legs.

On bearing strength topic, this is why I have used two bearings on one guide (two plates are transparent):

Did not do any strength analysis/calculations yet. Will get back to it if Cannondale solution does not work.

 

[speedmd]

Hi Circuit

As I mentioned before, this would be costly and heavy. Precision movement is not needed for a few inches of dampened suspension travel. You still would be limited to shock travel in the suspension travel. The simple link / pivot design with shock would work just as well and be much less expensive, much lighter for the same strength and easy to build with tubing. Your design would also require bearing carriages that can take load in all directions which are even more expensive. Interested in it, if and when you get to estimate the costs.

cheers

 

[magna_503]

I think that girder fork is nice. I'm thinking of building it.

Kinda like the ronin 47 motorcycle and confederate motorcycle

 

[Voltron]

Linear bearing do work... Several Yeti designs used them on the back end. But they sure aren't a weight saver....

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