Building a 304 stainless steel ebike frame?

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saiyan

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hey guys,
just a quick question, i am currently thinking of building my own custom ebike frame out of 304 grade stainless steel sheet. something similar to the stealth bike frames. i just want to have inputs on how strong it will be as i will be using it for downhill riding occasionally.

cheerios.....
 
I occasionally work at a bike frame company that specializes in highend Stainless frames. They dont use 304, is some special alloy Reynolds 953 tubing but I dont know much about the alloy. Remember to passivate it once you are done!
 
You'll lose a bit of toughness and strength/kilo vs the 4130 Crmo that bikes such as stealth features.

Are you chasing stainless for the visual look?
There's a few CrMo vendors up your way in the aircraft business.
 
saiyan said:
hey guys,
just a quick question, i am currently thinking of building my own custom ebike frame out of 304 grade stainless steel sheet. something similar to the stealth bike frames. i just want to have inputs on how strong it will be as i will be using it for downhill riding occasionally.
Click to expand...

300 series stainless loses all its hardness when welded. It only hardens by means of cold working. So you'll end up with the lowest strength at the joints where stresses are highest, and no practical means of restoring the material's strength.

Don't use 304 stainless. It's not the right choice for a bike frame. 410 stainless would be better. Even 410 is only as strong as mild steel, though.

But why stainless? Chromoly is stronger, easier to work, and cheaper. If you want something less subject to corrosion, 6061 aluminum offers better strength-to-weight ratio, and can be heat treated after welding to restore its pre-weld strength.
 
I agree with chalo, chromoly is amazing. Easy to work, easy to weld, easy to bend (kinda, the thin wall stuff likes to kink). Aluminum is even easier, but the heat treatment process kinda sucks.
 
Thanks for the help and info guys......I was just curious of how well the ss would hold up but it seems it wouodnt do so well.
I might be going the route of cromoly steel if I do end up doing the build. The main reason why I want to make a custom build is to
Hold the large amount of batteries I want to put into it......
 
John in CR said:
For stainless I believe it's 17-4 stainless that you want.
Click to expand...

Hmm. That is a good material. It is so strong for a stainless steel, that I had previously believed that it wasn't weldable. But I looked it up, and sure enough, it is.

17-4 is the stuff used to make stainless steel bottom bracket spindles and pedal spindles. Industrially, it's usually heat treated after welding to make its properties consistent throughout.
 
hmmm
had a stainless-steel nippon bike in the early 70's
...lasted half a season before the frame cracked and the welds gave it up
But 17-4 would likely work as it's not all that "stainless" (it rusts)
 
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