Home Made Bikes

Author Message
flag curbwzrd
Posted: Mar 14, 2020 at 12:47 Quote
photo
photo

trying to wrap my head around building a single pivot dual susp. so far the most daunting task seems to be trying to learn fusion360! built the shock in fusion first as it seems to be a good first project. eye to eye set to 230 mm, and max compression set to 60 mm.

the plan is to build something that doesnt require any machining, based off of the curtis xr650 - but with 29" wheels.

probably going to use a headset and steer tube as the pivot.

anyone else tackle a dual susp?
flag EarninTurns
Posted: Mar 15, 2020 at 17:05 Quote
Hey Guys,
I've been a long time lurker. Only now started in on actually attempting to put my ideas into CAD. My big issue is finding standards that I can model parts off the shelf parts from. Where do I go to find CAD drawings of forks, shocks, hubs, etc? Or are there documents out there that give standard dimensions??? I just can't seem to find where to start. Seems like a dumb question but I just can't figure it out!
flag MTBLegend92
Posted: Mar 15, 2020 at 19:51 Quote
EarninTurns wrote:
Hey Guys,
I've been a long time lurker. Only now started in on actually attempting to put my ideas into CAD. My big issue is finding standards that I can model parts off the shelf parts from. Where do I go to find CAD drawings of forks, shocks, hubs, etc? Or are there documents out there that give standard dimensions??? I just can't seem to find where to start. Seems like a dumb question but I just can't figure it out!
Fox, Rockshox/Sram, and some of the framebuilding suppliers have relatively easy to find part specifications/drawings. Shimano's drawing are for the most part much harder to find but they do also exist. You can also measure the actual parts on your bike.
flag DanAlmberg
O+
Posted: Mar 17, 2020 at 11:27 Quote
photo

I drew mine in Autocad Inventor. Only the front in 3d but i could at least see that it all would work Smile
Ridden the bike for about 1500 kilomerers now.
flag jamieridesbikes
Posted: Mar 18, 2020 at 8:10 Quote
photo
Got some dropouts laser cut through Fractory which I'm pretty stoked on. Files arrived yesterday so pretty much ready to start!
flag alted
Posted: Mar 18, 2020 at 12:25 Quote
EarninTurns wrote:
Hey Guys,
I've been a long time lurker. Only now started in on actually attempting to put my ideas into CAD. My big issue is finding standards that I can model parts off the shelf parts from. Where do I go to find CAD drawings of forks, shocks, hubs, etc? Or are there documents out there that give standard dimensions??? I just can't seem to find where to start. Seems like a dumb question but I just can't figure it out!

Hi,
Heaps of stuff here https://grabcad.com/library?page=1&time=all_time&sort=recent&query=mountain%20bike
Just double check a few key dimension before you go ahead and manufacture.
flag smalltownboycustoms
Posted: Mar 19, 2020 at 14:26 Quote
jamieridesbikes wrote:
photo
Got some dropouts laser cut through Fractory which I'm pretty stoked on. Files arrived yesterday so pretty much ready to start!

Fractory advert keeps popping up on my Instagram. How were they? Also how much did this order cost?
flag jamieridesbikes
Posted: Mar 19, 2020 at 16:52 Quote
smalltownboycustoms wrote:
jamieridesbikes wrote:
photo
Got some dropouts laser cut through Fractory which I'm pretty stoked on. Files arrived yesterday so pretty much ready to start!

Fractory advert keeps popping up on my Instagram. How were they? Also how much did this order cost?
Super happy with them, barely need any smoothing or touching up. Tiny marks from the last bit of the cut but pretty clean otherwise.

They do instant quotes on their website, dunno if you've used 3D hubs or Weerg but it's pretty similar. Good to have a play about with different ideas/materials etc. I've tried a few things and the minimum order is around £70-80 plus shipping.
These are mild steel but you can also get stainless and aluminium. I think they can do stuff like countersinking and threading too.

Got a few spare if anyone's after some...
flag anoplura
Posted: Mar 19, 2020 at 21:54 Quote
curbwzrd wrote:
photo
photo

trying to wrap my head around building a single pivot dual susp. so far the most daunting task seems to be trying to learn fusion360! built the shock in fusion first as it seems to be a good first project. eye to eye set to 230 mm, and max compression set to 60 mm.

the plan is to build something that doesnt require any machining, based off of the curtis xr650 - but with 29" wheels.

probably going to use a headset and steer tube as the pivot.

anyone else tackle a dual susp?

1. Headset and steerer tube as the pivot is a very good idea.

2. The Curtis XR650 is a very good bike to base your first attempt on.

3. Not requiring any machining isn't very realistic. There are online machine shops that can fabricate the parts you'll need based on simple 2D (or 3D!) drawings if you can't find someone local.

4. Approach this project with the idea that it will take twice as long, and cost 50% more than you are planning. Plan to make mistakes. Try to make those mistakes as early and inexpensively as possible.

Specifically, I strongly recommend that you make your forward shock mount bolt-on and adjustable. With a simple single-pivot like you are proposing, you want to be able to play around with the leverage ratio. You can pretty easily give yourself a few options in terms of overall leverage ratio and ramp up by adjusting and swapping out the forward shock mount.

Also, the best way to mount the swing-arm is with collet-style clamps on both sides of the axle. This requires some planning and machining. Pinch bolts are simple and easy, but will always introduce a torsional (twisting) load. If you have a large enough pivot axle (head tube) this may be insignificant, but between the thru-axle in the back and pinch bolts in the front, it's always possible that you're introducing enough twisting force that the load on the pivot bearings or shock will lead to premature wear, if not decreased performance.

Lastly, I strongly suggest adding some cross bracing between the main pivot on the down tube and the seat tube. There's already a ton of twisting load on the back end of the Curtis, and I'm not impressed by how they added a simple gusset that just thickens the tube - with no real bracing. Once you increase the axle diameter by using a head tube (again, a very good idea!) the rear end will be significantly stiffer, and the twisting forces will be too great for the down tube to take on it's own - gusset or not. A couple of parallel plates from the down tube to the seat tube would be ideal.
flag R-M-R
Posted: Mar 20, 2020 at 4:08 Quote
anoplura wrote:
Try to make those mistakes as early and inexpensively as possible.

This is great advice that's often overlooked. If there is a difficult step that would ruin the rest of the project if it goes wrong, do it as early as possible so less work is at stake if it fails.
flag shirk-007
O+
Posted: Mar 20, 2020 at 10:51 Quote
anoplura wrote:
3. Not requiring any machining isn't very realistic. There are online machine shops that can fabricate the parts you'll need based on simple 2D (or 3D!) drawings if you can't find someone local.

Not true.

You can build it with little more than a file, a bench vise and a hacksaw. Trust me, I've actually done it.

Photo collection here.

https://www.pinkbike.com/u/shirk-007/album/Smashy-Bike-Build/

I used printed miter templates to generate my miters and hand cut them. Was it perfect alignment? No, but it doesn't need to be.

The frame above was built without linkage or CAD. I drew a full scale drawing and used cardboard to rough out the shock position.
flag jukka4130
Posted: Mar 22, 2020 at 12:00 Quote
anoplura wrote:
curbwzrd wrote:
photo
photo

trying to wrap my head around building a single pivot dual susp. so far the most daunting task seems to be trying to learn fusion360! built the shock in fusion first as it seems to be a good first project. eye to eye set to 230 mm, and max compression set to 60 mm.

the plan is to build something that doesnt require any machining, based off of the curtis xr650 - but with 29" wheels.

probably going to use a headset and steer tube as the pivot.

anyone else tackle a dual susp?

Also, the best way to mount the swing-arm is with collet-style clamps on both sides of the axle. This requires some planning and machining. Pinch bolts are simple and easy, but will always introduce a torsional (twisting) load. If you have a large enough pivot axle (head tube) this may be insignificant, but between the thru-axle in the back and pinch bolts in the front, it's always possible that you're introducing enough twisting force that the load on the pivot bearings or shock will lead to premature wear, if not decreased performance.

Very good advice, much appreciated!

Could you specify the collet-style clamps a bit more? I couldn't think of any axle configurations in bike frames on top of my head which use that system.
flag SleepingAwake
Posted: Mar 22, 2020 at 12:50 Quote
Longest project i was ever working on, but my road bike is finally finished:

diy road bike frame

diy road bike frame

diy road bike frame

diy road bike frame

Super happy with the result, even tho there are quite a few little things that are bugging me. especially with the paint job. The lower half isn't supposed to be this textured, but rather a satin gloss. But the paint got old and i can't get fresh one due to the corona virus and all stores being closed. Wish me luck that the head tube doesn't come off on the first descent...
flag R-M-R
Posted: Mar 22, 2020 at 13:00 Quote
There are high-end production bikes that don't look that good. Here's hoping the ride is equally nice!
flag SleepingAwake
Posted: Mar 22, 2020 at 13:18 Quote
R-M-R wrote:
There are high-end production bikes that don't look that good. Here's hoping the ride is equally nice!

I actually don't think ride quality will be great. Probably too stiff, then no flex in the seat tube with the head mounted in-line, and the enve fork takes tires only up to 25mm width... I'll report back!

 


Copyright © 2000 - 2024. Pinkbike.com. All rights reserved.
dv65 0.022171
Mobile Version of Website