Womens Issues

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harry76

harry76

Well-Known Member
Apr 16, 2011
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Brisbane, Australia
Hi i would like to make my girlfriend a vintage style motorised bike, and i wish to use a ladies frame, only problem is id really like to keep the motor below the upper of the two bars on a ladies frame, to achieve this i may have to stretch the frame and/or remove the lower downtube and fit a droploop to make clearance for a motor..... I know i can place the motor above the upper toptube but im not really fond of this, id really like it out of the way. Have you seen this done?

I guess what depends if this is possible is what motor i decide to use. I will probably use whatever i have that works the best. Ideally id like to use a 3.5hp Briggs i have and lean it to follow the ladies frame downtube. I have a centrifugal clutch to use with it....... i also have a 50cc Chinagirl i can use/steal from another ongoing project. Any thoughts?

I did just buy a more modern ladies mountainbike with straighter downtubes which should provide more clearance. I will post some pics when i get a chance..... and pickup the new bike.

I also intend to have a little tank either up near the headset or behind the seat...
 
harry76

harry76

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Apr 16, 2011
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adam valentine said:
i have seen them modified on a drop loop with a modded upper tube on board track racers but we would need to see the bike or attach a email like
Click to expand...
As i said ill attach pics when i get this new bike, but i just wanted to see what ideas are out there as i may want to source another more appropriate frame to modify....
 
harry76

harry76

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Apr 16, 2011
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Brisbane, Australia
Heres two of the possible three motors i have to use, the other would be a 50cc Chinagirl i have.

3HP Briggs with centrifugal clutch....





Villiers 98cc....





Although the Villiers would look a lot lot better for this build i think the Briggs would be a lot more friendly to ride for my girlfriend. Any thoughts?

I think i might run another sheave if i use either of these two engines or if i use the 50cc obviously i will use a chain and sprocket.
 
harry76

harry76

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Apr 16, 2011
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Brisbane, Australia
adam valentine said:
i have seen them modified on a drop loop with a modded upper tube on board track racers but we would need to see the bike or attach a email like
Click to expand...
The bike i would use would either be the newer female mountainbike i bought but havent yet picked up, or the same as this malvern star ratbike i built for my girlfriend, they are cheap and readily available over here in Oz....






 
harry76

harry76

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Apr 16, 2011
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I had this Malvern Star ladies bike that had a bent seatpost. I could probably repair it but like i said these bikes are plentiful and cheap so i decided to cut this one up as a trial. If and when i get a look that im happy with ill replicate it with a new frame.



The bent seatpost...



I lengthened the frame and would just need to make a droploop downtube to clear the 3hp Briggs. I would just have to leave enough room to clear the carb and exhaust. And i would just need to improve some of the angles of the frame. Remember this was a junk frame and this is just a trial....





Ill have to see if it will work as far as being able to make a jackshaft work and clear pedals etc......Itd be cool if i could get the jackshaft to fit inside that triangle section above the cranks. Id like to get the top piece of that triangle section to be more horizontal.

Do you think this design would be strong enough with a briggs? I dont wanna kill my girlfriend
 
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MEASURE TWICE

MEASURE TWICE

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Jul 13, 2010
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I looked at the cut tube and the mock set up with the Briggs below. What came to mind is how some builds use the engine as an interconnection of the frame. Although the idea of modifying the casting of the Briggs would not be what I mean, at least maybe a tube that comes to near the cylinder head and uses a few bolts to hold it in place. Use a bracket in between the connection so that the cylinder head is torqued in place with all bolts in as it is attached to complete the frame.

An engine mounting plate could be built to hang from a weld to the above bar, but adding additional as per above paragraph would be additional strengthening to hold the engine.

Measure Twice
 
harry76

harry76

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Apr 16, 2011
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Brisbane, Australia
The bike would have a drop loop downtube, i dont have a pipe bender so that has to wait until next time im at my friends. I would make an engine plate and also a mount that attaches to the headbolts to the downtube.
 
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
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I rode a girls bike some last summer with a 50CC China Girl engine. At the time I had nothing else to ride as my other bikes had burned up in a fire. It was an easy and fun ride. And a few years ago I built a couple of ladies models Schwinn Americans... solid, good looking rides.
If it were me, I think I would keep the bike simple and relatively light weight, so that when she pedals it there isn't a lot of weight to move down the road. Make it really user friendly and simple... and look like a girl's bike with a girl's color and some elegance. This is your sweetheart, so make her a sweetheart of a bike with nice lines and such. What's cool for you might not be as cool for her. This will be her first motorbicycle so if you do this right and she get's to love riding you'll have a riding buddy of the best kind.

Most newer girls bikes here in the states are not very suitable for a motor as the upper down tube is too high in the frame, making the engine sit too high. It should be as low to the pedal crank as possible, so here in the states the best bikes for this are the older ones, especially those made by Schwinn during and before the 1950's. But maybe you do not have suitable frames available ready made. The one you have cut into could make a nice one for the little China Girl motor. If I had a second frame available and could start over, I would take the upper down tube (the one you cut) and leave the curve at the bottom of the tube alone... but cut it away from the seat post and mid way in the straight portion of that same tube you cut loose, cut it again so that it can have a section welded in to lengthen tat tube. So that down tube would run from where it is right now on the fork tube (head tube or whatever you call it) and the lower curve would get welded in lower on the seat tube, as low as you can go. Now there is room for the China Girl down low which will leave her plenty of leg room for mounting the bike. You will need a longer cable for the kit throttle so that the cable can follow the front down tube to the bottom bracket... continue around and up the seat tube... loop under the seat and to the carb. It makes a long route, but without sharp bends and keeps the open area in front of the engine clear for her foot to pass through. Yes, a behind the seat gas tank and everything should go together nicely. It will be simple, elegant and light weight. Hopefully your girl will think it's the cat's meow. You can score big, Harry. You can always upgrade later with a shift kit and gears if she wants more speed or hill climbing capability.

Another whole different approach is to use a smaller men's frame, like a 24" cruiser with the China Girl. You know her and have an idea of what she would like... or ask and leave it to her. Then she has some investment of herself in her bike. Good luck, Bud.
SB
 
wheelbender6

wheelbender6

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Sep 4, 2008
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Because ladies actually care about their clothes, I would probably do a rack mount for her. The China girl can be rack mounted, but will require a little fab work to do so. Briggs motors are a bit heavy for rack mounting.
 
harry76

harry76

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Apr 16, 2011
2,557
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48
Brisbane, Australia
wheelbender6 said:
Because ladies actually care about their clothes, I would probably do a rack mount for her. The China girl can be rack mounted, but will require a little fab work to do so. Briggs motors are a bit heavy for rack mounting.
Click to expand...
Just personally im not fond of rackmounts. I dont like the look of them and with all that weight up high i cant see how this would be friendly to a beginner rider. But thats just my opinion.
 
harry76

harry76

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Apr 16, 2011
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Brisbane, Australia
SB my girlfriend has no real interest in MB's so she may not even want to ride it, so i think i will please myself but consider her riding it, because more then likely it will end up like the other bikes i have built her..... just sitting collecting dust.

In Australia we dont have many bikes to choose from and certainly not some of the prettier earlier ladies frames you do. Its pretty much this style frame or newer female montain bike (i just bought one and have to pick it up). And shes not very tall so she likes the step thru frames so that rules out a small mens frame.

And i figured, besides maybe the weight (but in this frame mounted very low may be not too bad), that the Briggs with centrifugal clutch would be a far easier ride then a chinagirl?

You mentioned leaving my top bar alone and cutting and lengthening it and mounting it lower doen the seattube. Would i be doing this to mount the motor above that toptube? If so this is sort of what im trying to avoid, and if not isnt that just making a weaker frame design (less distance connected to the seatpost, i.e smaller triangle) and making less room for a motor under this bar.

The way i have the frame now (with a minor tweaking) and a droploop downtube would leave enough room for the briggs. Question is what would be the most rider friendly bike? Briggs or Chinagirl powered bike?
 
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
8,325
670
113
northeastern Minnesota
Harry,
My comments regarding the tube modification were with the idea of a china girl motor installed just above the bottom bracket. If she isn't really interested and may not even ride it then make it however you want. In many ways the Briggs would be a better choice aside from aesthetics. The vibration coming through the frame with the China Girl is not pleasant and many women I am sure would prefer an automatic clutch to a hand clutch. Easier takes offs, etc. I was thinking mostly in terms of looks, guessing at what a girl might like... what I know about what women think you could fit into a thimble, so follow your best instincts and budget, I guess. Good luck, and with a woman involved you will likely need it. I've been married three times and a number of girl friends through the years, yet have learned virtually nothing. Strange and wonderful creatures.
SB
 
harry76

harry76

Well-Known Member
Apr 16, 2011
2,557
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48
Brisbane, Australia
I saved this bike from a friends dumprun.



I stripped it of the junk, fitted a springer fork i had (needs a little modification), changed the bars, cut the downtube for more motor clearance and i really like what i came up with.







 
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harry76

harry76

Well-Known Member
Apr 16, 2011
2,557
47
48
Brisbane, Australia
I sat the motor in for a trial, just need to make sure the inlet manifold and the exhaust clear the top tube. I will also make a small inframe tank near the headset. I need to find suitable wheels for it. I think it will be belt drive. And it will have front and rear racks....



 
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