Suggestions for bug out build

justpassinthru said:
Hi all...been lurking for a while, great group here. Have a project. I am building a motorized bike with trailer that can get my wife(she doesn't ride bikes) and myself back over 130 miles of broken Seattle (Olympia) to South of Portland interstate highway. We spend time at our sailboat moored several hours away in South Puget Sound. Based on updated big one earthquake analysis the main Interstate freeway I5 will be even more toast then previously through most of Washington. Yes extreme thinking but lets put that aside.
So I need to be able to haul 330 lbs of people and 50 lbs of gear, 380 lbs. That will be the sole use of and purpose for this build. I have obtained an aluminum two wheeled trailer that hitches to the seat post (will be customized). (Will make sure trailer can handle weight) I just obtained a Diamondback, 26 inch wheel 20 inch steel frame used mountain bike.
Hoping for some of the great critique I have learned immensely from on this site.
4 or 2 stroke? Speed not a high priority, 15-20 mph is fine. Reliability for that 130 miles, critical. Will be carrying fuel with us so optimizing fuel usage will save weight.
What I think I should be concerned about...
reliable clutch, will carry a spare but with the excess weight and some gradual inclines, need a good clutch setup.
reliable carburetor
rear sprocket tooth size?
spoke or solid hub chain wheel setup?
prefer to not go as complex as a stub axle setup
Brakes sufficient?
single chain transmission acceptable?
Ditch the 21 speed derailleurs? I will be losing the shifting handle bar grip shifters...
We will probably stop and take breaks but would "like" the option to ride further if we didn't want to expose ourselves to potential lawlessness.
Bike and trailer will break down to be stored in trunk in several pieces, would like the engine to be able to be placed on its side (with oil and fuel removed)
Used the template described on a you tube 10 1/2 by 10/12 with one corner trimmed to confirm engine fit in frame, barely fits...tight..

Any feedback greatly appreciated....


View attachment 166349View attachment 166351
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I'm building one tht is going to be super quiet and have multiple gears. I have been requested to build bug out bikes. I'm still in r&d. Designing the transmission right now. Have to test out a few idea's before I figure out which idea works best for the bike I'm building. I'm going 4 stroke for it. I usually use 2 strokes, because I love my CG's. This bike kind of happened on accident, an I have a floating 4 stroke, so I'm using 4 stroke.
 
As for the 3x7 drive with the right kind of shifters both can be put on the left handlebar. A 3x7 gets shifted like this lowest to highest gear ratios:

1(1-4), 2(2-5), 3(4-7) for 12 sequential non redundant ratios.

If a gear is too easy or too hard to comfortably maintain a cadence (crank rpm) of 70-90 it means you're in the wrong gear. Take off gears are 1(1) for take offs going up hill and for all other take offs use 2(2). If you use a single ratio engine drive system a multi geared bike gives you more ratios to slect from to efficiently pedal assist the engine when necessary.

You can buy fairly inexpensive bicycle computers with a cadence meter on them.
 
Karl Snarl said:
I'm building one tht is going to be super quiet and have multiple gears. I have been requested to build bug out bikes. I'm still in r&d. Designing the transmission right now. Have to test out a few idea's before I figure out which idea works best for the bike I'm building. I'm going 4 stroke for it. I usually use 2 strokes, because I love my CG's. This bike kind of happened on accident, an I have a floating 4 stroke, so I'm using 4 stroke.
Click to expand...
There is and will be a big market for bug out motorized bikes. You will do well.. I'll have to keep an eye on your posts to follow your transmission R&D. From my naive perspective in this new to me world of motorized bikes, the weakness of the centrifugal clutch on 4 strokes is a big concern as reliability in a post apocalyptic world which preppers plan for doesn't allow for breakdowns.
 
Sidewinder Jerry said:
As for the 3x7 drive you can put both shifters on the left handlebar. A 3x7 gets shifted like this lowest to highest gear ratios:

1(1-4), 2(2-5), 3(4-7) for 12 sequential non redundant ratios.

If a gear is too easy or too hard to comfortably maintain a cadence (crank rpm) of 70-90 it means you're in the wrong gear. Take off gears are 1(1) for take offs going up hill and for all other take offs use 2(2). If you use a single ratio engine drive system a multi geared bike gives you more ratios to slect from to efficiently pedal assist the engine when necessary.
Click to expand...
You are a stand out on this forum for mechanical knowledge, I ran across many of your posts and gave immediate credibilty, Thanks for offering up wisdom to mine. I may be an old man 67, but am an avid hill climbing cyclist. I restore and ride vintage racing bikes. So gears are a big part of my life and cadence is the sweet spot... These mountain bike shifters are new to me, hence the question. I like the idea of doubling them up on on bar that would totally work. Your comment of using the pedaling at different cadences to assist the engine I can understand. Wasn't sure just how much pedaling is done with one of these bikes. I have now reframed this new concept to motor assisted riding, vs pedal to get started and full motor. That helps, thanks Jerry.... Growing up we had a Sidewinders dirt motorcycle race track near me, your name isn't derived from that track?
 
justpassinthru said:
There is and will be a big market for bug out motorized bikes. You will do well.. I'll have to keep an eye on your posts to follow your transmission R&D. From my naive perspective in this new to me world of motorized bikes, the weakness of the centrifugal clutch on 4 strokes is a big concern as reliability in a post apocalyptic world which preppers plan for doesn't allow for breakdowns.
Click to expand...
You can burn any clutch up if the engine is put under engine strain. This is where a tachometer comes in handy. With a single ratio drive a multi drive bike gives you more ratios to efficiently pedal assist the engine.

In my case I have a triple chainring shift kit. The reduction range is 66.79:1 to 16.25:1

I use a 33cc 4 stroke engine. I'm 250 lbs, the bike weighs a 100 lbs and I've pulled 200 lbs in my pull behind trailer up 30% grade hills. So there's no danger in burning the clutch out if the right gear ratio is being used for a given task.
 
justpassinthru said:
a post apocalyptic world which preppers plan for doesn't allow for breakdowns.
Click to expand...
Which is exactly the reason for things being made as simple and uncomplicated as possible...The more parts and modifications used on our little machines, the more that things can go wrong and you will not have the right items to fix it in the field...I even keep an extra CDI, magneto, and li-on batteries and light sets in faraday bags just in case of EMPs...DAMIEN
 
a B.O.B. trailer will be easily maneuverable and can carry a load. Kind of hard to park though, as it only has one wheel. It also mounts to the axle.




Wasn't there a guy on this forum that had like 20 trailers on his MB?
 

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