Need swing bike frame designs

[yoothgeye]

A few years ago I made a swing bike, I did no research and just eyeballed everything to make something. For some reason I convinced myself that the rear pivot at the seat post was too hard, turns out it looks easier than what I made. This girl in my youth group can ride the heck out of my bike and it's pretty wacky. The angles are off and when you swing way out to the side the back of the bike points upwards. I remedied this slightly this year by taking the 20" wheel off the front and putting a 16" on. I think she would have a lot of fun if I build something better.

I'm not going to put anymore time into this bike and after seeing the 2 Swingbikes that just sold on recently I saw that all I really need is the frame of the swingbike (the backbone) and two 20" forks.

Does anyone have a Swingbike that they can lay down and trace or put some measurements/angles on along with a good profile view of one? Or maybe designs are already out there somewhere. It's just that I remembered that I just got about 5 sets of 20" muscle bike forks that I have nothing to do with, and this should work great!

Here's the one I built:

 

[GuitarlCarl]

I've been thinking about building one too. I think the rear pivot needs to be almost vertical to alleviate the tilt issue... I'm collecting parts for my build and that's the direction I'm taking... I've also seen repop rear clips on the bay before... Good luck with your search!
On second look, does yours have centering springs???

Carl.

 

[yoothgeye]

No, no springs, didn't see much need for them.

 

[yoothgeye]

Check out the angles on an original swingbike:

 

[ozzmonaut]

I made mine with the same basic angles as the originals. I used the rear triangle lower part, bolted it to the fork to keep it even, and then welded the braces in. It was much simpler than what I originally had in mind. For the frame I just took the two headtubes and connected them with conduit I bent by hand. Mine looks much like the frame above, but not exact. However I doubt my measurements would help since they aren't the same as originals. If you look at youtube for swingbike vids, one guy posted a video with the opening shots being some graphed out swingbike sketches. By using the image above and assuming the rear wheel diameter is a true 20", I would say that the distance between the headtubes is about 30" . I made mine a little longer to help me clear obstacles.

 

[yoothgeye]

I know the video you are talking about.

Maybe I just need someone with a swing bike to fill in the blanks for me...

A- front headtube height in inches
B- rear headtube (seat tube) height in inches
C- top from outside to outside in inches
D- bottom from outside to outside in inches

 

[yoothgeye]

I like your backbone design, it looks really nice. I wonder just how close I need to be? Mine is messed up because of the center hinge design, but maybe "close" is good enough?

 

[The Renaissance Man]

I have never even heard of a swing bike before seeing them on this forum, so I could be completely wrong in my thinking.
But it seems to me that the main concern would be the trail for both ends. If the trail is set up correctly, I would think that you could even ride it with 'no hands'.
Everything else would could vary without much effect other than comfort.

Just a guess though!

 

[yoothgeye]

On both of these builds there was a lot of trial and error, assembly and disassembly, cutting and repositioning welds before I got either right. And, yes, just a degree or two matters.

This, I did not do, I like to take the easy way out, so this is a lesson for me.

My current swingbike has been played with and ridden in 3 years of Christmas parades, but the only trial and error I have done was a couple weeks ago when I realized "Hey, if the bike lifts when you swing it out... maybe a smaller front wheel will help" and it did. I'm betting a shorter fork would help too. Not that anyone is wondering, but the entire bike is made from a men's 26" USA made Roadmaster mountain bike. Only the extra steer tube (and bolt-ons) came from different bikes.

As for riding with no hands... haha, no. Standing and riding... barely. I'm pretty good with it in tight places, and I can "criss-cross" straddling cans spaced out in the road, but I'm not as good as those guys on youtube.

 

[LukeTheJoker]

Those guys on YouTube are awesome! (And one of them is a member on here!)

As for degrees and dimensions, for mine I found a side on pic of an original and zoomed in till it filled the screen and took measurements from that to get my dimensions, then I blew it up even further and used a degree finder on the front and rear headtubes, then it is a simple matter of working out scale compared to what rear wheel you want to run...

Luke.

 

[The Renaissance Man]

I suppose no hands would be a stretch!
The smaller wheel does have an effect on the trail. Of course the fork and the head tube angle are all parts of the equation as well.

Hmmm...I got nothin'.

 

[DJ Bill]

I'd like to help but won't be near my bike until almost Christmas. I'm working oversize escorting from IA to TX till then. I purchased mine off Ebay mainly to get a pattern to build my own from. I was planning on using a 26 inch Girl's bike frame or two...and fork to build it. The only difference I am going to put in the new design when I do it, is I'd like to make the bike slightly longer and slightly higher, as the bike fits a 12 year old perfectly and I am a bit larger.

Have you seen the video/instructable on how to build your own? I think he mentions the angles somewhere there. You may also find better pics you could blow up on Bob Huffords SB site.
Check out the last homebuilt swing bike on this page for a larger copy of the same basic design.
http://swingbike.byethost24.com/bobhufford/swing.html

 

[DJ Bill]

<a href="http://s1296.photobucket.com/user/FBilljeeps/media/bills bikes/DSCN2087_zpseb4147ba.jpg.html" target="_blank"><img src="http://i1296.photobucket.com/albums/ag3/FBilljeeps/bills bikes/DSCN2087_zpseb4147ba.jpg" border="0" alt=" photo DSCN2087_zpseb4147ba.jpg"/></a>

Best I can do is a copy of my avatar pic..
Note the fork is slightly bent and the pic was taken from a slightly higher position than the bike.

A couple of design thoughts.. Front headset has more rake than rear. Frame tubes get closer as toward the front for some reason I cannot fathom. The more crossed up you get the more you notice the front wheel leans opposite the rear wheel.

 

[Sinner4]

My home built has both head tubes at 70* I think it works best at that angle

 

[DJ Bill]

Okay, from a neat swing bike video on Youtube, a comment someone wrote:


They aren't real complex. How detailed do you want? An original swingbike had a 39" wheelbase axle to axle. These two have a 49" wheelbase. 20" rear fork and wheel. 26" front fork and 16" wheel. You will want the steerer tube for the rear fork to be tipped forward at the top some, but almost vertical. You will want the crank to be level or slightly lower than the rear axle. This will help make it stable. The seat post is basically a stem or gooseneck with an extension for the seat to bolt onto.

Now for some dimensions from my own bike:
a=5.5 b=4 c=25.5 d=28
Seat is about 32 inches off ground.
Rear axle to crank centerline is 16.25 and crank has 6 inch arms.
Front headset is about 16.5 degrees from vertical.
Rear headset is about 6 degrees.
Inside length between the headtubes at the tube junction top of top tube is 23, bottom of lower tube is 25.25
Overall tubes are 2.5 top to bottom front and 3 in the rear so the taper is about a half inch. I can't see this as an important design feature.

Sissy bar top to axle is about 26 inches. A 24 inch sissy bar will be too small for adults.
20 rear tire, 16 front.
Bike has had a rough life so may be somewhat off dimensionally. I would guess my measures are within two degrees and a 1/8 inch.

I managed to sneak home for a day so if you need any other dimensions or pics let me know ASAP.

 

[LukeTheJoker]

DJ Bill to the rescue!

Luke.

 

[DJ Bill]

The guys on YouTube don't seem to have the spring setup....and it hasn't hurt their riding at all. They are GOOD.

Pause it about the 3-4 second mark there are some drawings and dimensions.

 

[yoothgeye]

Thanks Bill, this should be more than enough information. I pulled out 4 20" muscle bike style forks yesterday, I need to find a 26" now... I think I gave my last one away.

 

[ozzmonaut]

I don't run a spring on any of mine. I think that was more for kids who might have trouble training themselves to use their body to return the rear to a straight riding position