Minimalist FD

GoldenMotor.com

cannonball2

Well-Known Member
Oct 28, 2010
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Colonial Coast USA.
The Zip Bike is kinda similar to this bike I built several years back. Was a great FD!


http://motorbicycling.com/attachment.php?attachmentid=43111&d=1323973089built

The Schwinn was a great bike too. Direct drive it ultimately turned a 3.75" roller for a top speed of 44mph. Had to pedal to around 15mph then dump the clutch and hang on.
I still have the sister bike a Mongoose. Have more miles on this bike (around 8k) than all the others combined.

http://motorbicycling.com/attachment.php?attachmentid=41361&d=1319321541
 
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Ludwig II

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Jul 17, 2012
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I'm going to post those 2 elsewhere, they should inspire some though and possibly construction afterwards.

The Zip, whether it's the result of construction or of planning, has a look much like the original friction drive Whizzer.
 

cannonball2

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Oct 28, 2010
3,682
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Well the seller for the 1 1/8 roller hasn't seen fit to Post it yet.

Wanting to see if my theory about the engine being under driven was correct I wrapped the 7/8 roller with Gorilla duct tape topped with several layers of friction tape to a diameter if 1.125". That fixed the 4stroking. Its under constant loading while under way 2stroking as it should. It settles down to a nice buzz instead of the rather loud 4stroking. Amazingly it pulls the 1.125 roller very well. I had my neighbor that was behind me clock me with her Prius. Did a solid 22mph wound out. Cant complain about that! especially with only 21ccs!

Its silky smooth save for a harmonic(varies with rpms) that I believe is from running a 3/16 piece of key stock for the drive shaft when its really supposed to be 5mm(its loose in the drive). Got a piece of 5mm on the way. Also figured out if you pull the one screw in the throttle control and loosen the engine clamp you can remove the power head while leaving the mount and clutch assembly on the bike. Takes about 90secs. This is useful for riding well regulated bike trails.

So this is really a keeper. Its so simple and works so well. With the little Echo total weight added to a bike is around 6+lbs. This is the lightest powered bike I have had. Love it!
 
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curtisfox

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Dec 29, 2008
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I think my Bike Machine Motor has a 1 1/4 " roller, also its about 50 cc. This is good to know, i have a brand new 4 stroke in the box Toro i Bellevue. I just may slap one together, LOL.............Curt
 

cannonball2

Well-Known Member
Oct 28, 2010
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Curt, the one I cobbled together is a 1 1/8. I bought a 1 1/4 BMX peg last night. Was really hard to find. Most are either less than an inch or 2".
Wanted to have a choice of a bigger roller. The guy finally shipped the 1 1/8.

Primer bulb gave up, and the common leaking Echo fuel tank grommet needed replacing. Look what all I got for less than 20 bucks! Carbs alone used to cost over $50. This is the same seller but my stuff was shipped from Califorina. Cost $3 more.

http://www.ebay.com/itm/Carburetor-...977855?hash=item3f631ff2ff:g:iN8AAOSwdWBXOuUu

Got the 5mm drive shaft installed. Took care of the harmonic vibes and is much quieter with no play.
 

Wickedest1

Member
Oct 31, 2012
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I love it man. Outstanding. And as ludwigII said about sharing, they did get a lot of conversation from all over the globe.

I had the same issue with getting roller sizes just right, and came across some info that suggested creating your own roller from a harder duro rated rubber. I luckily have a rubber supplier within a reasonable distance from me. I explained what i was doing, and he helped me out. It's rather easy to come across a high duro rated rubber sheet. And you can get all types of thickness as well. I settled on a 1" thick section and utilized a hole saw to achieve different roller sizes. I also sandwiched multiple"holes" of rubber to get a 4"wide roller.

I'm also not sure about the echo motor, but the weed eater motor i used had that square adapter just bolted to the flywheel on a thread crank. I used threaded rod coupler and high tensile threaded rod as my roller core.

http://motorbicycling.com/showthread.php?t=53561
 

cannonball2

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Oct 28, 2010
3,682
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Colonial Coast USA.
Thanks W1!

I would have loved to run a rubber roller. I still have a piece of the good stuff I used originally. Problem with the Echo(and advantage) is it has a 3/8 24 threaded shaft. Remember this one is running the trimmer head. The big advantage here is there is no loading on the crank bearings. The shaft wasn't long enough to run a stacked rubber roller. I believe I did similar to what you did(threaded coupler with a bolt) with a 31cc Poulan build I did.

Most BMX pegs are dual threaded now with 3/8 24 on one end 3/8 26 on the other but smaller in diameter(1"). The ones I just bought are older 3/8 26x 1 1/4. Will run a tap thru the threads to fit it to the unit. The Lawnboy 1 1/8 roller actually measures 1.148. It suits the bike very well. I wanted a 1 1/4 roller also. I think that's about as big as a 21cc will handle in the flats. So far the tire wear seems non existent/ very minimal with the LB roller. Has excellent grip.

Once I add the .75L fuel bottle this one is put to bed.
 

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Got and modified the BMX peg. If I still had my lathe I would have turned a bit off the nutted end. As it is its a perfect fit to the area of the tires contact. I trimmed off about 2.5 and retapped to 3/8 24. The is peg actually 1.32"

I havent ridden it out on the paved road but it worked fine on our sand/gravel island road. It is the max size for the 21cc. Have to help it to about 10mph then it begins to develop power and slowly accelerate. Will do much better on pavement.

So this is an easy cheap way to get a minimalist lightweight MB. Makes for a neat little bike you can throw in the car, ride bike trails(engine off or quickly removed) with almost no additional weight. I came in way below my 10lb limit. It requires minimal fabrication, less than an hour. Was thinking about a total bolt on/ together method, but that may very with the brand of trimmer.
The newer 26cc trimmers make good power and cost around $79. This method will work with any bike with the common non suspension fork. So if one has a bike laying around a MB could be constructed for a $100 or so using a new trimmer. If you yard sale it 1/3 to 1/2 of that. Just don't use a trimmer with a bushing head, also it must be a curved shaft not a straight shaft trimmer.
 

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curtisfox

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Dec 29, 2008
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WAY KOOL! Maybe you should think about getting a small lathe, snoop on the Bay for used one. LOL...........Curt
 
Jan 17, 2015
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That really a nice idea. Before I got the 'build bug', I rode a bike most everywhere for like 7 years. Now with no peddlin, for 2 years, if it wasn't for side jobs, I'D get no exercise!!!and its showing..lol like you say, peddle out, motor back.