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Motorized Mountain Bikes and Road Bikes Motorize a full suspension mountain bike to get a smother ride or for a little more speed try motorized road bicycles. This section is for sharing ideas on motorizing your mountain and road bikes.

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  #1  
Old 05-26-2016, 06:42 PM
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Radar00 Radar00 is offline
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Default MTB to motoped/Enduro/dirtbike thing

Well today I started the butchering of my old MTB.

I was inspired by this thing.

[IMG][/IMG]

It had been sitting in the shed rotting for the past 5 years. Has front and back suspension and I actually have two of them. Rescued from the trash years ago.

[IMG][/IMG]

chopped the head tube off since i'm going to make a proper C type frame thing like the motoped in the above pic. I'm using a length of 36 in gas tube for that. and will basically just cut and re-weld the tube in the proper frame shape since bending isn't going to happen. The gas tube is like 1/8th thick.

[IMG][/IMG]

Chopped and cleaned up the front forks. The irony is- the handlebars are rusted in there so I have to bang em out (eventually. For now I'll keep em together just to get a better idea when I lay out the frame over the weekend.

[IMG][/IMG]
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  #2  
Old 05-26-2016, 10:46 PM
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Agreen Agreen is offline
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Default Re: MTB to motoped/Enduro/dirtbike thing

Looks cool! You have my attention now
__________________
Never stop wrenching
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  #3  
Old 05-27-2016, 09:28 PM
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Default Re: MTB to motoped/Enduro/dirtbike thing

Not much really done today. Only really got to chop up the rest of the bicycle to get the rear tire and suspension. I laid out the frame for what I'm thinking. Still haven't decided on the engine yet. So far overall wheel base is 51in which suits me just fine. The tires are the original 24in MTB tires which i'll keep until the frame is rolling. The seat tube will come off the down tube and I'll add some gussets which will help me mount that rear suspension. Additionally I'll put a fairly large gusset between the top and downtube and once i decide on an engine, i'll figure out how to close up the frame (depending on engine size)

Interestingly enough I have some old cranbrook front forks laying around. I'm tempted to put a large engine in this frame.
[IMG][/IMG]

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  #4  
Old 05-28-2016, 07:21 PM
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Default Re: MTB to motoped/Enduro/dirtbike thing

So after some grinding and welding and measuring I finally have something resembling a frame. It seems like nobody knows how to change a rear tire as this one's dropouts were bent so I have to torque them back into proper alignment. Next is welding the the frame together solidly. This is basically just tacked together at the moment to check for alignment. I'm going to also have to cut some 3/8 steel plate and begin making gussets for the joints for added strength and also figure out how im going to join the whole thing together. Also waiting on my engine which is just going to be a cheap chinagirl for now. maybe in the future i'll put something better in it.

[IMG][/IMG]

[IMG][/IMG]

[IMG][/IMG]

Originally this was going to be like a dirt bike but due to the length of the wheelbase, it's looking more like one of the sportsman frames. Atleast I think so. Even still with dirtbike plastics on it and a headlight it could still pass i think
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  #5  
Old 05-29-2016, 10:34 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

I like the idea of a backbone frame.




Simple and rigid if the tubes are large enough.
If your going to make the tubes larger, you might as well use them to hold fuel:





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  #6  
Old 05-29-2016, 10:36 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

Another nice design that only needs pedals:
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  #7  
Old 09-09-2016, 10:10 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

Quote:
Originally Posted by Agreen View Post
Looks cool! You have my attention now
And mine too !!

_
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  #8  
Old 09-10-2016, 12:08 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

The motoped concept is of interest to me, too. That pedal/jackshaft arrangement looks like the weak link, though. Also I don't see any reason to use 26" MTB wheels and tires, as the Motoped does. Another weak link. Both problems can be solved, IMHO, by using a moped wheel and 17" trail bike tire (CT90, etc.) on the back. Probably on the front too.

Seems a shame not to use some kind of small motorcycle engine, complete with gears unless you are trying to remain legal in a state that doesn't allow gears on a motorized bike. Even then you can get a single speed, 50cc clone of the Honda horizontal engine.
Another option would be a small-motorcycle 2 stroke engine. Maybe an RM80 or similar.
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  #9  
Old 09-10-2016, 01:40 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

Since I posted this I've kind of scrapped the frame I originally built and am looking at buying a junked dirtbike/moped frame and then modifiying it. I'll post more as I find a frame thats suitable
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  #10  
Old 09-10-2016, 11:29 AM
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Default Re: MTB to motoped/Enduro/dirtbike thing

You might consider starting with a Honda Z50, XR50 or CRF50 frame and building on that. It is a backbone frame that is designed for the horizontal Honda engines, and the clone engines from 50cc all the way to 160cc are designed specifically to fit it. Put long forks and swingarm on it, add some 17" wheels and you're almost there.

I built something similar using a Honda XL70 frame, longer forks and swingarm, and 17" rear/19" front wheels with a 125cc clone engine. I ride it everywhere and have several thousand miles on it. But a 50 frame might be an even better starting point.

Here's my little bike:
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