Dedicated E-bike Downhill/Freeride frame and build

[e-beach]

The swingarm was designed with topology optimization and I was surpized at the number of windows vs pockets. It is CNC machined form 6061-t6 aluminum........

Looking very nice!.....

On the swing arm, what about getting large enough aluminum tube, cutting it in half and welding it to the outside of your swing arm. ( or maybe cut and weld the tube in sections to match contour shape of your swing arm.) It would increase the stiffness if you need it. It would also match the look of the rounded fork tubes. It would however also create pockets for mud to collect, so a flat piece of sheet might need to be welded on the inside to seal the swing arm and keep the mud out. It would stiffen it up though.

 

[Daedalus]

just been looking at the blog, so nice to see the bike taking shape, plus it has a mix of alu and steel in there. Is it an Epoxy bond your using to hold the components together? I ask as if component failure happens it will be a pain to swap them out
The web design of the rear swing arm looks ace, its good to see the test rides have found improvements as a test rig should never stay static, its a living entity always to evolve
I would be very interested in the frame alone as most parts are available for the shocks etc from most MTB stockists for me to track down to build it up.
I'd love to get more information on the type of controller you used for this as the pack voltage is substantial and would require a ruggedised setup to survive knocks.

So Far, Top Job on the build, very impressed. keep going 8)

 

[Schlafmutze]

Is this frame going to be for sale? if so when :lol:

Really interested in this.

 

[kdee122]

The swingarm was designed with topology optimization and I was surpized at the number of windows vs pockets. It is CNC machined form 6061-t6 aluminum........

Looking very nice!.....

On the swing arm, what about getting large enough aluminum tube, cutting it in half and welding it to the outside of your swing arm. ( or maybe cut and weld the tube in sections to match contour shape of your swing arm.) It would increase the stiffness if you need it. It would also match the look of the rounded fork tubes. It would however also create pockets for mud to collect, so a flat piece of sheet might need to be welded on the inside to seal the swing arm and keep the mud out. It would stiffen it up though.

Welding is great way to make bikes (and racecars, my "real" job). For my bike project there is no welding for two major reason. Heat treatment and distortion. When you weld aluminum you lose approx 50% of the strength in the heat affected zone (for typical TIG welding this is the weld bead and all areas within 3-4mm of the weld bead). However you can fix this with heat treatment. Heat treating large parts is a bit tricky to get the proper cooling rates in all areas of the parts. However since I live in Taiwan, the bike making capital of the world, there are many great fully automated heat treating companies.

The nasty part of heat treating is distortion. For a part the size of my bike swingarm I would expect 2-3mm of distortion. The way we handle this in the "real world of manufacturing" is large steel heat treatment fixtures. These could reduce the distortion to maybe 1mm. With the rise of complex suspension systems for mountain bikes the bike industry began to have lots of trouble with alignment of frames and suspensions systems. The answer was post heat treatment machining! This take a large, typically 5 axis CNC machine, its quick but very expensive.

In short once (or if) I sell enough frames and bikes to justify building two more sets of fixtures I will look at welded aluminum. Until them I am limited to my bolted and bonded construction and no molds or fixtures. I am even more likely to move to composite for the swingarm.

I do plan to sell just frames if there is interest.

The frame was designed for the Cromotor and other large hub motors. I wanted to build a bike that would handle well and inspire confidence with more than 10kw. I have been adjusting the wheelbase, head angle, and swingarm lengths and it starting to feel pretty good! I finally got the low speed handling to be as good at the high speed handling.

 

[e-beach]

Welding is great way to make bikes (and racecars, my "real" job). For my bike project there is no welding for two major reason. Heat treatment and distortion. .........

Ok, the parts for firming up the swing-arm could be per-manufactured to be bolted on. Sandwich your swing arm between a flat sheet on the inside and a preconfigured, prewelded 1/2 tube on the outside. You could even bond it as well as bolt it. The outside 1/2 tube configuration could even be milled flush (after welding) on the face that meets your swing-arm, ....if you have an accurate jigging system. That way you can get the tolerances under 1mm.

 

[Daedalus]

sorry, just put the brain in gear after i posted that, i remeber from my TIG welding days the distortion and the slight fatigue of the metal around the welding location by the heat.
I like the bolts showing anyway
Not that it should have taken any effect by now, but are the threads plated to reduce / remove the affect of the interaction with the steel bolts and Alu frame?

 

[kdee122]

The aluminium parts are all anodized and the bolts are likely to be stainless steel or steel bolts with a special corrosion plating. One of the problems on the prototype has been corrosion of the bolts, but this is easy to fix.

 

[Daedalus]

out of curiousity, what did you use to charge the cell packs, i assume they were Li-ion or Li-poly cells. I'm building my cell packs at present from 18650 unprotected's but at a loss to locate a protection PCB and charging solution that will cater for the big packs as most are geared around the cell packs being 6 cells and below

 

[Lurkin]

Please advise of the following:-
- frame weight
- estimated price
- whether you are building a light weight version and it's eta (you have advised in other threads you may do this)
- whether you found lighter weight 21" MC tyre options and what they were.

I have been watching this for a while and I could be tempted to buy a frame. How far off are they?

 

[rider95]

The thing I see with all the unibody frames is frame flex I am olden enough to rember Unibody cars

 

[L.E.S.contractors]

What are the specs on this downhill, what kind of motor and battery does it have. Are you selling it? If you are, you can email me at L.E.S.contractors@gmail.com

 

[aluminumwelder]

so what every happened to this project? all photo links are dead, blog is dead, and youtube channel doesnt' even show a clear shot of the frame. maybe original creator could release dxf files and give others a crack at it. Seems like too many bike projects die and with them all the knowledge of how they were made.
which means new people interested in making bikes have to start from scratch.

 

[spinningmagnets]

Sounds like he's in the middle of negotiating a business deal.