Step-Through MotoPed*?

UncleKudzu

New Member
May 26, 2008
353
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Deep in the American South
would a "girl bike" (no top tube) frame be strong enough to make a motorized step-through?

heh... upon closer inspection, the old piece of rust i bought today appears to be a girls bike with a top tube half-a**edly welded on :oops: no wonder i'd never seen a frame quite like that!

the bike has horizontal drop-outs and a coaster brake. i could put a 5-speed hub on there pretty cheap, i think, and be done with the derailler when it comes time for the Pablo and Ghost jackshaft kit...
 

UncleKudzu

New Member
May 26, 2008
353
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Deep in the American South
thanks, fairracing! that engine sits pretty high, huh? the bike i bought today is a rusty old Murray which has the two down tubes like that one, but they're curved in such a way that the engine would sit lower.

i think this old bike might make for an interesting build if i got rid of that top tube that was so crappily stuck on it, but i'm still wondering about the strength of the girl bike frame geometry; seems like a triangle missing a leg. wonder if the chances of sudden catastrophic frame failure would be in any higher than on a men's frame if i bolt on a little Morini?
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
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north carolina
My first build was on a 24" schwinn girls bike. I called it the sissy schwin. I used a broom stick for a top bar to mount the gastank on. Was a nice little bike and i ran it a lot of miles before I decided to go for a bigger bike.

Check out the bottom picture on my blog it is the sissy schwinn with broom handle
 

UncleKudzu

New Member
May 26, 2008
353
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Deep in the American South
Check out the bottom picture on my blog it is the sissy schwinn with broom handle
thanks, deacon! a broom handle, huh? you should just go ahead and build a wooden bike ;)

yeah, that looks more like the frame i've got, except this one does have 26" wheels. very rusty wheels, but 26" nonetheless. i wish my camera was working

i think i'll call her The Defiant, since i'll need a little attitude if i'm gonna be riding a girly bike :)
 

Cabinfever1977

New Member
Mar 23, 2009
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Upstate,NY
thats a good idea,you dont have to worry about clearance issues,no top bar to get in your way.but after i mounted the engine, i would mount a long skinny pole there just for the looks and maybe for a tank mount.
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,583
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thanks, fairracing! that engine sits pretty high, huh? the bike i bought today is a rusty old Murray which has the two down tubes like that one, but they're curved in such a way that the engine would sit lower.

i think this old bike might make for an interesting build if i got rid of that top tube that was so crappily stuck on it, but i'm still wondering about the strength of the girl bike frame geometry; seems like a triangle missing a leg. wonder if the chances of sudden catastrophic frame failure would be in any higher than on a men's frame if i bolt on a little Morini?

Enter "The Dragon Lady"..fly

I have a girlie cruiser. Her first transplant was a front electric hub running 72vdc and 80lbs of batteries. A very enjoyable ride except for the hassle of charging batteries and carrying the bike up two flights of stairs daily.

I could also FEEL the frame flexing from the excess weight when the cruiser tipped the scales at 135lbs (The bike originally weighed 45lbs).

I moved on to gas engines. I could not fit the Happy Time engine into the 2006 Raleigh Retroglide single-speed frame. So I started with a 2.2hp 43cc Mitsubishi engine w/friction drive and 1.125" roller.

Then I changed to 1.5" roller and an expansion pipe. Top speed was 30mph, rpms over 9,000rpm.

Then I added a SECOND engine up front. It was another 2.2hp Mits engine w/1.25" roller.

Acceleration was awesome! Top speed was now about 36mph with front engine screaming over 11,000rpm.

Front roller changed to 1.375". Acceleration was still very good and speed increased slightly to about 38mph. Engine pushing over redline to 10,000+rpm.

Front roller changed to 1.5" and another expansion pipe added. Acceleration is slightly sluggish but speed increased to 39.3mph. Engine revving to 9400rpm, slightly over redline. Both engines are singing happily.

Side-pull vee-brakes added front and rear, in addition to rear coaster brake. Braking is excellent, even at high speed and riding in traffic at 35mph+.

I have absolutely no problems with my twin-engined girlie cruiser, even though it now weighs 91lbs.dance1
 
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commander

New Member
Mar 19, 2009
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penn state
Pretty nice Heaven, you have 2 motors and 3 gas tanks. Looks like your ready for any problem, surprised you dont have a spare tire attached also . hahah
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,583
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Thanks, commander.

Reserve tank automatically feeds engines' tanks. The siphon bulb purges the air from the lines.

If I could carry a spare I probably would.

Got three flats in three months on the bikepaths. Sooo, I put an old tire casing AND a thorn-resistant tube INSIDE the new tire casings. I also avoid the bikepaths as much as possible and ride on the road.

No flats so far(knock on wood)..rd.