Help me build a Frankenbike

[Wayneburg]

I've been researching what kind of gas powered bike I'd like to get and I haven't found one that completely meets my needs, so I'm considering making a Frankenbike. I'm hoping you all would help me out.

Here's what I want this bike to do:
-I want it to be as quiet as possible.
-It will be ridden on paved streets mostly.
-I want to ride it in an upright fashion like one would ride a beach cruiser. I'm 6'1" and I don't like to ride hunched over the handlebars.
-I want it to be lightweight.
-I don't want any resistance on the pedals when the engine is off.

Planned uses for this bike in order of priority:
-Daily commuting to and from work/school (16 miles round trip)
-Fun
-Running errands
-Cross country road trip if the bike is as fun as I'm hoping

Here's my idea:
-4 stroke engine- Quieter than 2 strokes. I'd like to use the bike's gears together with the engine for increased efficiency. I hope I can use a lower powered engine to get the same speed as a higher powered engine.
-Road bike frame- Lighter than a mountain bike or cruiser.
-Wider tires than road bike tires. I'll even consider having tires on the bike that are different widths. I'm not sure if there would be any advantage to this, but I thought I'd throw it out there to see what you all thought.
-Mountain bike handle bar with longer stem positioned so I can ride upright.
-One dual pull two finger brake lever- Lighter than two individual brake levers.


Considerations:
-I'm considering frame mounting because I think it may be lighter in weight than rack mounting. Also I'm not sure if a rack mounted setup will allow the engine to be used along with the bike's gears.
-I'd like to have a setup that puts no resistance on the pedals while the engine is off. I'm not sure if there is a clutch that works with frame mounted setups that puts no resistance on the pedals when the engine is off.


It'll look weird, but I don't care. I think it'll work. Do you have any advice?

 

[sparky]

Sounds like you mostly know what you want. If you want a daily rider, and most definitely if you want something to go across the country with... then you definitely need a 4-stroke, IMO. 2-strokes are more fun to me as a n00b and they go faster with the same displacement (versus 4-strokes), supposedly even uphill which I thought 4-strokes would win at since they have more torque.

Only other tip I've got for right now is that suspension is way more important to me than having a lightweight frame. Having the dual freewheeled hub was also number one on my list since I wanted a chain-driven setup for my first motored bike (Only dealers I've seen with this dual freewheel hub are Five Flags who made my foldable bike, or Staton Inc, who have NuVinci kits which are supposed to be as good as it gets).

I've got a lightweight 20" BMX that always has good resistance on the pedals, but it's not a traditional BMX... it has front & rear shocks which give for a pretty comfy ride. I couldn't imagine riding on a bike with no suspension, but some areas might have flawless pavement all over the city. Mine isn't like that.

So, the top priorities I have for any bike I'd buy/build:
1) Street, kevlar tires with thick tube & tube liners
2) LocTite the mounts and other bolts suspect to vibrating off
3) Rack-mount with full-suspension frame
4) Thumb throttle
5) If chain driven, must have dual freewheel hub

Those all have at least *some* safety benefit to them, and I wouldn't sacrifice any of them for speed, looks, or especially being lightweight. Safety should definitely come first for everybody on a motored bike. I also find it funny that I haven't seem anybody come on this forum and ask for the safest motored bike possible. There has prolly been one or two before, but it's definitely not asked enough by n00bs.

 

[Wayneburg]

So, the top priorities I have for any bike I'd buy/build:
1) Street, kevlar tires with thick tube & tube liners
2) LocTite the mounts and other bolts suspect to vibrating off
3) Rack-mount with full-suspension frame
4) Thumb throttle
5) If chain driven, must have dual freewheel hub

Thanks for all the great info. I'm looking up everything you've mentioned, but I'm having a little trouble finding info on dual freewheel hubs. As far as I can tell there are more than one kind. Would you mind going into more detail about the one you are referring to? Thanks

 

[Simon_A]

A couple of thoughts on your idea's.
1) Street, kevlar tires with thick tube & tube liners
Street tyres are great, low rolling resistance, but they suck in the wet.

I don't want any resistance on the pedals when the engine is off.
Try a centrifigal clutch setup, like pocketbikes, the bell has the lowest weight and therefore less mass to move.

One dual pull two finger brake lever- Lighter than two individual brake levers.
Working out the bias would be the only fidly bit. I intend to do the same on my next bike. I have the dual lever already.

Road bike frame- Lighter than a mountain bike or cruiser.
Bear in mind the extra vibration and loading that these engine put on a bike. I think thats why most choose a mountainbike frame for its strength. Roadies are designed to be as light as possible at the expense of wall thickness.

Good luck with the build.

 

[Wayneburg]

A couple of thoughts on your idea's.
1) Street, kevlar tires with thick tube & tube liners
Street tyres are great, low rolling resistance, but they suck in the wet.

I don't want any resistance on the pedals when the engine is off.
Try a centrifigal clutch setup, like pocketbikes, the bell has the lowest weight and therefore less mass to move.

One dual pull two finger brake lever- Lighter than two individual brake levers.
Working out the bias would be the only fidly bit. I intend to do the same on my next bike. I have the dual lever already.

Road bike frame- Lighter than a mountain bike or cruiser.
Bear in mind the extra vibration and loading that these engine put on a bike. I think thats why most choose a mountainbike frame for its strength. Roadies are designed to be as light as possible at the expense of wall thickness.

Good luck with the build.

Good points. I'll have to do some research in tires that are good for road and wet. Looking up the centrifugal clutch you suggested. I'm also considering an older model road bike frame that is made of steel. They made them sturdier a in the 70's and 80's.

 

[sparky]

1) Street, kevlar tires with thick tube & tube liners
Street tyres are great, low rolling resistance, but they suck in the wet.

And what new kinda tires do you know of that are better on wet roads? Off-road tires certainly aren't. Street tires are better than off-road tires on wet roads. But the quality of the tire's compound is of more importance than anything really.

 

[sparky]

... but I'm having a little trouble finding info on dual freewheel hubs. As far as I can tell there are more than one kind. Would you mind going into more detail about the one you are referring to?

Any hub that has two freewheels on it. Other than the Five Flags one & the Staton NuVinci setup, I've only seen BoyGoFast or someone selling some kinda hub adapter on eBay, but even after you buy all that stuff and get it laced up, it's not all that cheap.

I felt like taking the easy way out and getting something pre-assembled. The only other options for me were buying a full suspension mountain bike and attaching a Staton NuVinci kit to it. And that was too expensive for me since I didn't have a regular bike to build upon.

 

[frameteam2003]

Staton kits come with the dual hub.Staton uses a south paw freewheel on the left side for the motor chain drive side.Other side uses your 5/6/7 gear block.When pedaling the motor drive side freewheels so has no real drag as the drivechain does not move.Staton hubs also have 4 sealed bearings(very nice hub)You could knock out the balls on the inter bearing set and just use it as a spacer if you wanted. I advise using a frame with a springer fork.When under power you will need some suspension.
Plus:for the statons are the 4stroke motors
great hub
dependable and easy to work on
no drag when pedaling
even 31cc motor has good power
Neg:mount high
some what diff to mount
gear box is(somewhat) heavy

 

[Wayneburg]

Cost is a big issue in my case. I suppose I'll have to give up one of my requirements to reduce the cost. The Staton products are too expensive for me. However, I am researching other frame mounted 4 stroke kits that are less expensive.

 

[sparky]

Well then, what's your budget?

Do you have a bike in mind that you'd like to use?

And where do you live, BTW?