Full suspension longtail bicycle (Folding)

[ngocthach1130]

Wouldn't the bike be very squirelly at high speed with the short wheel base and the front fork standing straight up like that?

[spinningmagnets]

At higher speeds, a longer bike may be a little more stable. My main interest was a more comfortable seating position that is lower and farther back (semi-recumbent?). I would only ride it when its stretched out.

Also, Dogman mentioned that it would be useful for a bike to be short enough to fit on the bike rack located at the front bumper of his city busses. The folding position is useful for the bus, and also when transporting this bike in the trunk of a car, or when moving the bike in/out of storage.

The front disc brake and "skewer" style front axle means that the front tire pops off-and-on easily without any tools.

[docnjoj]

That is really classy work, S/M! Oh yeah, I just noticed the drill bit "shaft" for the shock!
otherDoc

[spinningmagnets]

"...I just noticed the drill bit "shaft" for the shock..." Ha!...yeah, back brakes aren't hooked up, wood for spacers, derailleur cable held in place with tape...pretty much "salvage yard" engineering right now. I was just in a hurry to get it ridable. I am going onto night-shift, so hopefully I will have some time to upgrade the drill-bit pin and wood bracket!

Between the fat tires, old-skool cruiser seat (springs under seat) and the rear suspension, it rides much more comfortably over the pot-holes and rough sidewalks. My other commuter bike looks Dutch-style and has fat tires, but no suspension at all.

[John in CR]

Spinning mags-

Unless I missed something solid, the seat tube is going to need serious strengthening. Sure I'm heavy, but with pedals front almost all weight is on the seat. Mine is much shorter and it bent right away with a cromoly seat tube. Then I welded 1/2" solid steel rod inside with a reinforcement fillet in the corner, and it still bent somewhat. I'm surprised the seat tube on the frame never broke off with the leverage I put on it.

Red seat.JPG (30.56 KiB) Viewed 438 times

Yours is so long, even a featherweight is going to put serious stress (thousands of lbs with that kind of leverage) on the lowest parts of that seat tube.

John

[spinningmagnets]

I agree, John. I'm contemplating whether to add two supports up from the bottom (like a Mixte frame) or extending the top bar by adding a horizontal tube from the current seat-post top to the old seat-post hole. The Mixte supports could also incorporate a frame-mounted cargo rack that could hold two stealth panniers (to hide a rear hub, or a non-hub drive)

My main goal this week was to find out the most comfortable location for the seat. Now that I have the dimensions, I can begin designing a more professional-looking and stronger permanent arrangement.

I posted this in the General E-bike section because I hadn't seen anything like it, and I wondered why I don't see any examples of rear suspension long-tail (other than oldhaq's a year ago. He started this). I believe this can have a wide application, and many would benefit from it. Very do-able with no welding, and not very expensive. A vice, hacksaw, and a cordless drill at a minimum.

A folding NON-supension long-tail cargo bike with an RC-drive would be a piece of cake. Though I might make the effort to get aluminum for all the frame parts, and I'd use a 20" rear wheel.

I believe this thread has done its job, and I won't post again for a while. Once I have some significant improvements accomplished, I'll start a build thread. Thanks to everyone for your encouragement and support, I appreciate every response.

[spinningmagnets]

Build thread for version 2.0 can be found here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=19131&p=278822#p278822

I believe version 2.0 will be better in many different ways. I wanted to free up the bottom/rear frame triangle, possibly for batteries/non-hub-motor. The new seat post will be a front fork (to allow shock to pass-through). I have a small fork from a childs 12" BMX, but just about any solid fork could be cut to size.

In pic, the aluminum shown is lightly loaded as it only aligns a thick/flat thrust-plate which will transfer compression loads to the seat-post joint (shock will now be horizontal). "T" is a common cast brass 1/2" plumbing fitting. A screwed-in bushing can easily be drilled/tapped to common thread-sizes.

[Cyclebutt]

Yet another thread I must follow. Good stuff! Will there be more to come? Just noticed the date on the last post.

[spinningmagnets]

Thanks, but no. I just wanted to show what was possible without a welder, and using common garage tools.

This longtail was broken down into its original "short-tail" form when I moved from Utah to Kansas. I only have a one-car garage now (with the wifes car in it), and if I put together another longtail, I will use the Dogman method (shown in the longtail 2.0 link above).