New project idea

JerboaJohn

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Jul 29, 2018
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I saw that and thought the drivetrain is going to continuously preload some lateral torque. actually it could handle that but it's not rigid. it won't see any torsion unless he does the moto gp lean like he says haha. if it has enough travel, even it's flexy it'll still work but when will it fail to vertical flex? unknown.
I'd say thrash it at low speeds and see. just looks squirrelly to me idk. maybe it's fine??
 


LewieBike

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May 21, 2014
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454
The rear suspension member is muffler clamped to the seat tube.

*Muffler clamped* Let that little fact seep in and percolate.

This is not a well engineered bikeframe, especially with all the torque a lawnmower engine would pull through the combined bits. Hopefully it folds sideways before it even gets going, so he doesn't injure himself.
 

FurryOnTheInside

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Sep 23, 2013
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Timbone's photos can't show us the cross section or wall thickness of any parts of the frame. He showed that he did extensive reinforcement of the high stressed parts. If he says it's strong enough to be a bike, it's strong enough to be a bike.
I will infer only that it's bound to be heavier than a frame made from 4130 cromoly tubing and with more conventional single pivot swingarm mountain bicycle construction.
 

Frankenstein

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Jun 24, 2016
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So did you watch the video, that sh*t takes torque like a mother f***er.
There's a difference between unistrut (which the unistrut company makes) and the cheap crap one can buy at home depot.

I've held pieces of 4 inch flat I can bend over a knee, and 1 1/2 flat I've struggled to bend even with all my weight while it was firmly clamped in place. There is simply a huge difference in quality between materials, please don't show us inferior chunks of crap and expect us to believe all strut is made equal.

If you encase it in concrete it probably doesn't need to be all that strong, and as long as it lasts until the construction company owner is dead then it doesn't matter to him, some people want their projects to outlast their grandchildren, what they use to build with would make you think twice about your foreman and anyone in charge of him if you knew better.
 

Spare_Parts

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Nov 29, 2017
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If I knew better? You mean like telling someone his building materials are safe , even when they are obviously not, that kind of know better? You really think brand names are what matters on this build?

It's not so much "quality " as it is alloys. Pretty sure a flux core welder negates that.
 

curtisfox

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May 13, 2010
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609
You know I have been around home built and doing it for 60+ years. I see this frame with the main back bone of heavy tubing, with a strut welded in for a holding brace,it is welded good on both ends and then added extra steel welded at the joints, to me there is no way that strut can twist, and about the only thing it holds is the seat. And the main frame from spreading, don’t think this going anywhere. Study it and you will see..............Curt
 

Timbone

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Apr 20, 2014
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1,101
Gonna try and continue my progress reports. I’ve read all comments on my project and I figure the final product will speak for itself. The only comment I will make is that I’ve already succeeded in my proofs of concept and my works are steadier, stronger and better with each bike.

I’ve been traveling so I’ve lost some time. This is the first weekend in a while I’ve been able to work at this so here are pictures of my progress.

I’ve got the battery in it’s box and the basic wiring is done. The taillight is affixed and working. Same for the horn (you can see it near the minoshock under the seat). Chain is on. Motor is bolted on (!!!).

I’m nearing the finish.

My fuel tank is complete and leak free (I think!). I’ll weld on two tabs and lock it down with two bolts.

I wish I had a 4 stroke carb on hand that is easy to attach the throttle to. I’m afraid my carbs are less than optimal and may lead to a real struggle firing up this brand new engine. Constant problem solving.
 

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FNTPuck

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Jul 2, 2018
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Do you still have more supports and/or gussets to add? If your seating position is not all the way on the front of that seat to transfer all the weight to the post, it is going to bend after one good pothole or speed bump and you will find yourself sitting on the rear tire. That tiny little gusset doesn't reach far enough back to provide support for the bar the seat is on. You never ever see motorcycles or bikes with a single unsupported horizontal bar for the seat...even if that bar was proper closed tubing I still wouldn't run it like that and would add a support bar or much longer gusset that reaches to the middle of the seat. If you plan to ride it like that, wear a cup your first test ride lol.

This is a cool idea and I want to see it succeed, but some of these engineering details leave me scratching my head.
 
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