7005 aluminum

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t_tberg   100 W

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7005 aluminum

Post by t_tberg » Feb 21 2016 5:57pm

I'm starting my third build on an '05 Kona Dawg, this is the first time I'm using an aluminum frame. I believe the swing arm is the same material as the rest of the frame (7005 aluminum). Ideally I would like to get some custom torque plates made, does anyone know what the cost of something like this will be? The dropouts look to be 6-7mm, I may just use grins v4 torque arms since I already have one. Peak power will be about 2500w (20s). Has anyone used the '05 kona dawg with a hub motor or 7005 aluminum in general, what were your results?

t_tberg   100 W

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Re: 7005 aluminum

Post by t_tberg » Feb 22 2016 12:31pm

20160222_115508-min.jpeg

Raged   1 kW

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Re: 7005 aluminum

Post by Raged » Feb 22 2016 2:02pm

My old focus MTB was 7005. It was fine with a 2kw geared hub and a grin v4 torque arm.
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ebent   10 kW

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Re: 7005 aluminum

Post by ebent » Feb 22 2016 2:36pm

With that configuration why not put torque arms on both sides?
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t_tberg   100 W

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Re: 7005 aluminum

Post by t_tberg » Feb 22 2016 6:17pm

20160222_180328-min.jpeg
20160222_180328-min.jpeg (157.32 KiB) Viewed 412 times
The plan as of right now is to try to build some steel torque plates that would pinch the dropout between the plate and some kind of backing. Here is a quick sketch of what I'm thinking.

Punx0r   100 GW

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Re: 7005 aluminum

Post by Punx0r » Feb 22 2016 6:31pm

From the photo it looks like the brake calliper mounts are in the same plane as the outside of the dropout slot, so I would make a torque arm from steel plate that picked up on the nearest calliper screw (or both screws if you're running a lot of power). There's plenty of room below the dropout slot for a cross-bolt to make the arm of the clamping variety. Ideally you'd have a similar arm on the opposite dropout, but if your power level is modest then single-sided solution is viable.

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Chalo   100 GW

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Re: 7005 aluminum

Post by Chalo » Feb 23 2016 4:10am

7005 aluminum is fairly ordinary stuff that's comparable to 6061 alloy, the industry standard structural aluminum. In bike frames it has the unique benefit of allowing manufacturers to skip the solution heat treatment step of the hardening process, because in bike tube sizes it does that by itself at air cooling rates after welding.

Do not rely on any aluminum alloy to restrain motor torque applied through flats on a steel axle. The steel will always prevail.
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