Home Made Bikes

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flag huvudvind
O+
Posted: May 8, 2023 at 20:01 Quote
downhilljohn wrote:
I've been planning my dh rig for a while, do you design your bikes in CAD? If so, what program?

definitely definitely model your bike in cad. should be relatively simple and you would get a much more dialed final product for not that much extra labor. I would first model it in linkage to make sure the kinematics wont be terrible. ( look at an existing kinematics chart and try to get the numbers in roughly the same ballpark) . and then take your linkage dimensions and model them in cad.

Onshape is a beginner friendly pretty full featured online cad that i believe is free for hobbyists. But you will have to pay a little for a linkage license ( definitely worth it).

This will most likely save you headaches in the long run.
flag downhilljohn
Posted: May 9, 2023 at 12:36 Quote
I've been trying to model it in Fusion 360, but I might try this
huvudvind wrote:
downhilljohn wrote:
I've been planning my dh rig for a while, do you design your bikes in CAD? If so, what program?

definitely definitely model your bike in cad. should be relatively simple and you would get a much more dialed final product for not that much extra labor. I would first model it in linkage to make sure the kinematics wont be terrible. ( look at an existing kinematics chart and try to get the numbers in roughly the same ballpark) . and then take your linkage dimensions and model them in cad.

Onshape is a beginner friendly pretty full featured online cad that i believe is free for hobbyists. But you will have to pay a little for a linkage license ( definitely worth it).

This will most likely save you headaches in the long run.
flag soywater
Posted: May 9, 2023 at 17:34 Quote
[Quote="downhilljohn"]I've been trying to model it in Fusion 360, but I might try this[Quote="huvudvind"]

Buy linkage X3, it's $20? If you can do anything in fusion you can use linkage. Just play around and move stuff, see what it does to travel, leverage ratio, etc. Use that to make templates like suggested earlier. You might not get exactly what you wanted but it will get you really close.

As for the axle hardware, you can use whatever you want. I use the aluminum bits in an attempt to save some weight, the aluminum axle and nuts weigh less than a single, 3/4" steel nut. My garbage weighed 43+ pounds with all the steel hardware, just swapping aluminum bits in here and there (clevises, axle, cranks) I took over 2 pounds off it. Worth it? Don't know. It's just how I did it.
flag soywater
Posted: May 13, 2023 at 15:44 Quote
An increasingly irrelevant man, yelling into the darkness. Enjoy. I dare you.

flag mediocrityontwowheels
Posted: May 25, 2023 at 8:19 Quote
My homebuilt linkage fork

This thing is finally on the bike. I just need to get the stem on. I hope to ride it sometime today. Even just compressing it it feels way different, no stiction.
flag downhilljohn
Posted: May 25, 2023 at 14:21 Quote
How different does it feel? Do you use a rear shock for it?
flag hmbprider61
Posted: May 25, 2023 at 14:39 Quote
User name DOES NOT check out!! that is anything but mediocre. Bad ass dude. Cant wait for a ride report!
flag soywater
Posted: May 26, 2023 at 13:23 Quote
mediocrityontwowheels wrote:
This thing is finally on the bike. I just need to get the stem on. I hope to ride it sometime today. Even just compressing it it feels way different, no stiction.

This is awesome! Really interested to hear your thoughts on how it rides.


Here's some more of this stupid shit. Sorry.
flag mediocrityontwowheels
Posted: May 26, 2023 at 13:33 Quote
I did use a rear shock, a 250x75 Rockshox super deluxe air

I rode it around yesterday. It's crazy smooth and sensitive. I weighed it and it's, um, well, uh, 17 lbs. The weight makes the front end feel crazy planted, but bunny hopping is a chore. It doesn't dive under braking, it's weird and will take some getting used to. If you lock up the front wheel on pavement the fork basically won't compress because it wants to rotate around the axle when it goes through the travel, but it shouldn't be as big a problem on slippery dirt. The headset is currently being a pain but hopefully once that's resolved I can start getting some time on the trail!
flag R-M-R
Posted: May 28, 2023 at 17:29 Quote
mediocrityontwowheels,

Right on! So glad to see you went through with it - and so glad it's a leading link! The brake dive will be far superior. Leverage curve should be in the ballpark, too.

Damping can be difficult to get right, but with essentially zero friction, it's surprising how much the envelope of acceptable damping is expanded.

If it holds together - as I should hope it will, given the weight - you just might like it!

With a high level of anti-dive, you may find the braking traction on slippery surfaces feels less than expected. With less dive, the shear force on the tire's contact reaches a high value with less forward weight transfer, increasing the chance of slippage. You can adapt with a more forward posture during front wheel braking.
flag adm750
Posted: Jun 3, 2023 at 5:40 Quote
@mediocrity - That fork is really interesting. love it dude...! I would fancy a lap or two on that to see what it feels like.

hmbprider61 wrote:
User name DOES NOT check out!! that is anything but mediocre. Bad ass dude. Cant wait for a ride report!

absolutely agree..! clearly an attempt to throw us off the trail Razz

@everyone -

I can pretty much fix anything that has at one or more components to it and I lurk here because of that. But alot of the stuff you're doing is out of my skill zone.

Props to all of you for the time each of you invest into designing and building out your ideas. Salute

edit: and for sharing it !!
flag mediocrityontwowheels
Posted: Jun 3, 2023 at 21:28 Quote
Ride report:

Suspension wise, it feels amazing, very supple, amazing traction, no harsh bottom outs. I am running rebound fully open which feels normal. I was worried it would stiffen to much under braking but I never felt that, the braking felt actually pretty nice (I think I have it at 70% anti rise)

Handling wise, it’s absolutely terrifying. The weight makes it want to flop in the corners. Part of this is probably that this is the first time I’ve ridden my 26 since getting my mullet (plus old geo). I’m going to try adjusting the offset by changing out the shock and pivot brackets.

Structurally, it’s pretty stiff. My friend started the ride by hitting a 2’ drop to flat. From then on I stopped thinking to hard about it and just rode. On certain sections I rode as fast as I normally would.

Overall I’m pretty stoked. This thing is on a different level, and if it was lighter and handled better it would be by far the best fork I’ve ever ridden.
flag R-M-R
Posted: Jun 4, 2023 at 13:54 Quote
Thank you for the update, and keep 'em coming!

Do you know the head-tube angle and trail of the linkage set-up?

mediocrityontwowheels wrote:
Ride report:

Suspension wise, it feels amazing, very supple, amazing traction, no harsh bottom outs.

...

This thing is on a different level, and if it was lighter and handled better it would be by far the best fork I’ve ever ridden.

It's amazing what happens when the front suspension isn't restricted to a 1:1 motion ratio and friction is essentially eliminated.

Add the anti-dive properties, dynamic head-tube angle changes, axle path tuning, etc., and you can see why I want the industry to quit obsessing over lowering frames' centre of mass by three millimeters, concealing cables, ceramic bearings, and hubs with a million points of engagement, and put the R&D money where it can make a real difference!
flag whattheheel
Posted: Jun 4, 2023 at 17:02 Quote
Enjoy having you back Slacker!!lol
flag soywater
Posted: Jun 5, 2023 at 10:42 Quote
mediocrityontwowheels wrote:

Overall I’m pretty stoked. This thing is on a different level, and if it was lighter and handled better it would be by far the best fork I’ve ever ridden.

That's great news for the first version of anything! Now that you know it works you can fine tune the weight and handling. This is so cool, congrats!

 


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