Custom springer front, advice needed

Waspswatter · #1 08-29-2009, 04:32 AM

So I was thinking about making a springer front suspension using a spare Schwinn fork I bought online. Has anyone tried anything like that?

I took a few pics. I think I prefer the parrallel fork mock-up. The frame is pretty badly scratched, but I'm not going to re-paint it. I am, of course, going to clean the rust off the rims.

BTW, this is my first build.

Qdot · #2 08-29-2009, 06:30 AM

dig the bike man, pretty sure thats a 70's typhoon. I also made my own springer front end. Only thing to watch out for is how strong your welds are. Dont ask me how i know this.

Venice Motor Bikes · #3 08-29-2009, 10:56 AM

Thats gonna look cool!!!
I drew this up real quick to show how it might be done fast & easy, without any welding.
Also... Keep the original paint!!! (It looks way too cool!!)

Waspswatter · #4 08-29-2009, 01:18 PM

Thanks Qdot. It is a Typhoon, but I don't know the age, I rescued it from a neighbors back-yard

When I bought it, it actually had and old, (non running) bicycle engine mounted over the front tire. How cool is that?

Venice Boy, that's basically what I had in mind (using the "make your own springer front" tutorial I found on this site). Do you think it will be stable enough with only one spring in the middle instead of the usual two springs?

The only problem I have with the paint is that I need to match the paint for the other fork for the springer and the gas tank. The paint is also oxidized pretty badly. I think getting a good match is going to be difficult.

Here's how I found it...

tyrslider · #5 08-29-2009, 03:11 PM

Been working on a couple myself, springer (like yours) and girder (like Schwinn).

I'm concerned that if you push the axle forward significantly you'll get really dangerous handling. The front will no longer pivot but swing (sweep) instead (note pic of b'tracker fork legs are straight). Since this motion will be prevented by friction (tire grip) when you turn to the right your head tube will move left and vice versa. It may still work but it is w/o question a dangerous geometrical condition, especially at speed. At speed your rear wheel (the wheel that actually turns your bike in the corner 'cause when you countersteer your front is pointed to the outside of the corner) will be pointed sharper into the corner than it's profile would naturally orient it when leaned over.

By flipping my Worksman fork around I bought myself 4 inches of distance between parallels and returns my axle to the same pivot point.

Also if your gonna use reg forks and pivot your suspension at the axle points your gonna have to allow for movement and the slotted connection can be an issue depending on how you bear(ing) the movement (i.e what will hold the legs to their pivot points if they are loose to allow movement?)

Kevlarr · #6 08-29-2009, 04:33 PM

This will definitely solve your paint matching problem but you could heat both forks and straighten them since they're solid and not tubes. That would solve the problem with the steering geometry.

Also it wouldn't be too difficult to cut off the tube and weld on two long bolts so you could run double springs.

tyrslider · #7 08-29-2009, 05:05 PM

For the pivots bolts I've welded 2 grade 8 washers one on either side of each axle mt at the tip of the fork. And since my suspension is secured by bushings that'll be able to pivot, I'll have an additional pivot linkage at the top o' the fork using rod end bearings. That'll keep the fork legs parallel.

It's all about weight and leverage so it doesn't matter how many springs just the rating.

Waspswatter · #8 08-29-2009, 09:27 PM

Quote:

Originally Posted by tyrslider

Been working on a couple myself, springer (like yours) and girder (like Schwinn).

I'm concerned that if you push the axle forward significantly you'll get really dangerous handling. The front will no longer pivot but swing (sweep) instead (note pic of b'tracker fork legs are straight). Since this motion will be prevented by friction (tire grip) when you turn to the right your head tube will move left and vice versa. It may still work but it is w/o question a dangerous geometrical condition, especially at speed. At speed your rear wheel (the wheel that actually turns your bike in the corner 'cause when you countersteer your front is pointed to the outside of the corner) will be pointed sharper into the corner than it's profile would naturally orient it when leaned over.

By flipping my Worksman fork around I bought myself 4 inches of distance between parallels and returns my axle to the same pivot point.

Also if your gonna use reg forks and pivot your suspension at the axle points your gonna have to allow for movement and the slotted connection can be an issue depending on how you bear(ing) the movement (i.e what will hold the legs to their pivot points if they are loose to allow movement?)

Those are all excellent points, and I've given some thought to most of them. I planned to place the wheel axle between the two forks (about an inch more forward than it is now). This should be close enough not to cause any serious handling issues from changing the trail, (I keep studying the geometry and wishing it had more rake). PLacing the axle between the pivots should also keep everything together as the suspension "works" since a bump will drive the wheel (and the pivots) upwards into the forks. And like you said, I'd just use a spring that allows the right amount of flex for the job. I had thought about flipping the forks around like you did, but that moves the wheel too far back for me.

Kevlarr, I guess I could have someone else do it since welding is not yet one of my skills, (soon I hope!).

Did I miss something?

tyrslider · #9 08-30-2009, 12:33 AM

There's definately some tolerance for location just wouldn't push too far. Also depends on how you ride. In fact many choppers also produce dangerous handling characteristics and there are millions of those on the road!

Waspswatter · #10 08-30-2009, 01:55 AM

Haha, yeah, I've never ridden a chopper, but I rode a Harley once and didn't like the handling compared to my (performance oriented) motorcycle. I'm building this as close to a boardtrack racer as I can get, if that tells you anything about how I like to ride.

But it will still just be mainly for commuting around town and showing off.

Looking down the steering tube, I think there's about two inches of trail to the contact patch, (difficult to be sure with a flat tire) so I guess I'll just make sure I stay inside of that.

Now all I have to do is build it.