BrettMavrik's Production Bobber Frame For Builders Has Begun...

[Ardilla_Loca]

I think that something that would help everyone is showing the 0 rake and the stingray rake on the existing frame. It sounds like you'll be able to get the best of both worlds between the 0 degree and the stingray frame.

I'm more along the lines of your thinking in that I want to be able to RIDE the thing. I love the Triumph and the red bike.

Maybe people think it LOOKS like you have less rake but that could be a trick of the eyes because it doesn't have a tank. Love to see pics with both forks on.

Kris

 

[BrettMavriK]

Starting to take on the form of a bobber.....

Got busy today, so I wasn't able to do much.
I test fitted the tank and fender on the bike.
It's really starting to take on the form of a bobber.

I like it so far...

'BrettMavriK

 

[Ardilla_Loca]

Re: Starting to take on the form of a bobber.....

Lookin' VERY nice!!!! Where'd you get the tank and fenders?

 

[BrettMavriK]

ebay...

'BrettMavriK

 

[GeneFiorot]

There is lot of mis information about handling issues with an extended fork and big angle of the neck. And if the wrong geometry is employed a bike handling can become dangerous. The main issue that is often overlooked that if addressed properly is the trail measurement. If the trail is in an acceptable range the length of tubes and degree of rake becomes less of an issue. The Spoiler front end is an example where the bottom of the fork moves the trail measurement to an acceptable place and the bike handles fine. I have seen 10 foot plus wheelbase custom choppers without wheel flop. It is not just the length of the fork its all about trail. You can google a host of info on this issue along with various calculators to determine trail. Here is a site that has a good explanation of the geometry and a calculator.
RB Racing Rake and Trail Calculator

 

[Bikeguy Joe]

Good info Gene.

 

[Blue Collar]

Wow,

This sounds like a great start to getting a chopper that fits me with performance in mind.
So tell me about the jack shaft and motor mount that you say will be "isolated".
These will be made to fit this frame? What about the jackshaft sprockets/freewheels?
How fast will she go?

Once again, great job and I can't wait to see the the first born bike finished.

 

[Ardilla_Loca]

I've got a bid on e-bay for a 20" occ chopper. We'll see if it comes through. I know that it's WAYYYYY early in the development cycle but....just dreamin'. Keep up the good work!

 

[Ardilla_Loca]

I like the bobbers with the drag bars

 

[Ardilla_Loca]

Just picked up a chopper from craigslist. It's small!

 

[Youngbird]

I like the bobbers with the drag bars

And an adequate steering geometry.

 

[Ardilla_Loca]

It looks like you can vary the rake depending on the fork used. The best of both worlds!!

My dreams are filled with a 5 speed bobber and a springer front fork with a disc.....hmmm nice dreams!

 

[ZnsaneRyder]

Yes, there will be a separate clamshell motor mount / jackshaft mount option made for this frame, so it's all a bolt-on affair. It will make for a fun and easy build on an adult sized chopper.

Hey Inzane!
Yep, the frame is made spacious, so if you want to go Non-Happy Time motor, you have plenty of room.

Here is a photo of the spring loaded seat which will have a y-mount made that will enable the seat to slide up and down the frame for exact rider size positioning...

'BrettMavriK

Sweet. So a reasonably small 4-stroke like a Honda 50 or HF 79cc should fit nicely. Or a 2-stroke Pocketbike engine. That would be nice. Many people on the forums use these engines, and that frame would be great for many folks looking to make a nice custom bike.

 

[BrettMavriK]

Yeah,
It will be a very versatile and adaptable frame.
I've decided on putting a little more rake into the frame for the fork that still allows for good handling.
I'll be reworking the frame this weekend. I am also going to put in a crossbar from the bottom bracket to the fake seat post tube that will be the attachment point for the isolated clamshell motor mounts and jackshaft. After that I'm going to work on the clamshell sliding seat mount for the spring loaded solo style motorcycle seat.

When I'm done with this bike, the only cue that will give it away is the cranks.
Other than that, it's all motorcycle.

'BrettMavriK

 

[NunyaBidness]

I just wish I could spend a month or two down there. I could build one heck of a motorized full suspension mountain bike. Much like the one you're currently building, except for the cranks it's a motorcycle.

I'm sorry, I get inspired by genius at work and tend to daydream sometimes.

 

[BrettMavriK]

Funny you should mention that...
I've been conceiving a 5 speed, full suspension dirt bike in my head when I wake up in the morning lately. I have a 26" Mongoose with disc brakes and full suspension, and I'm thinking of building a steel frame that would accommodate an isolated motor mount with a double shocked, long travel rear swing axle and long mountain fork front.

Gotta stay foucused on the one thing for now however.....

The Bobber

'BrettMavriK

I just wish I could spend a month or two down there. I could build one heck of a motorized full suspension mountain bike. Much like the one you're currently building, except for the cranks it's a motorcycle.

I'm sorry, I get inspired by genius at work and tend to daydream sometimes.

 

[NunyaBidness]

Yea, somethin' kinda like this Project M85 - Image and Video Gallery of Project M85 in action but with pedals. More mountain bike than that, lighter and just as much fun. Motor would really need to be mounted firmly, with some 'cushion' from bumps, jumps and the style of ridin' I'd like to do.

 

[BrettMavriK]

Yep, I've seen that amazing concept.
Let's try to keep my thread on topic if we can.....K?
I gotta ' stay focused on this project right here:


Bobber Update:

I've drawn up the isolated motor mount / jack shaft mount design. Also, the sliding solo seat mount.
I'm going to start the fabrication process tonight. I've been trying to get the new shop
organized enough to where I can settle in and work.
I'll have some photos up very soon.

'BrettMavrik

 

[BrettMavriK]

Bobber Project Has Resumed....

Welp,

It's been a bit since my last post. I decided to revamp the garage into a shop by adding a wall for all the clutter and storage mess a garage becomes. So now I have a completely organized and clean shop with plenty of room, work benches, drawers, 220v, lighting, etc. for me to flow through my work more fluidly. I started back up on the bobber project last night, revamping the frame's front rake to a more desired amount while still retaining good handling characteristics. The shop is awesome! My mind is at peace as I work in my clean environment with my music. **sigh** =-]' Okay! back to the subject!

I played around with some figures and measurements for this frame to have more rake whilst still retaining proper trail and good handling. I came up with the magic number for this bobber and it's great.
The frame now has the perfect 30 degrees of rake and the trail comes out to 5.77". typical trail for good handling in the chopper world is from 4-6", so It's at the right of the spectrum but still within.
I tacked on a temporary seat to get a feel for it on a little ride down the block. She is Loowww.....
The spring loaded seat will sit at 24" off the ground at its' lowest. This is the sleek lowrider bobber frame I've been wanting. It still handles excellent, turns tight and tracks nice and straight.
So this will be the frame by which all other production bobber frames are built.

Next-
Today, I am going to add the mid-bar which will go from the seat post to the down tube and serve as the attachment point for the tubing clamp style motor mounts and jack shaft mount. Then I will begin building my version of a very versatile "clockable" isolated motor mount, and "locate-able" jack shaft mount.

more to come...

'BrettMavriK

 

[mobboss]

Love it man it looks great. I want one! I need the sonar bike 1st.Eta on completed photos?

Great work!