APAX style independent suspension delta

[SimpleSimon]

I've been thinking about bikes a lot for the last 18 months, and the APAX delta trike with independent rear suspension is just such an elegant design, it's a pity they are not going into production.

One of the biggest issues with delta trikes is their cornering ability. Secondarily, on bike paths and streets their width is a very real issue. So, in an attempt to kill both fowl (pun intended) with a single stone, here is a pic of a model I've been working on for an independent rear suspension trike, with co-axial jackshafts through the axis of pivot of the rear single arm suspension triangles to each wheel, to provide power to both rear wheels. Differential effect results from using a freewheel hub on each wheel - in effect the outer wheel in a turn is able to freewheel faster than the drive is pushing the inner wheel. It becomes, in effect, a leaner delta trike although the lean capability is a bit linited.

I like a low seating position, in the interests of keeping the CoG as low as reasonably possible, so I've gone with a crank forward design. I zoomed in for this pic to show the rear frame design - I'm still debating w/myself about what type suspension forks to use. As drawn, it is sized for 26" wheels, and there is plenty of room inside the main frame polygon for mounting an engine. The rear dropout subframe is sized for an NV CVT hub as a mid-drive, but that can be changed if one wishes.

I'll post more frame captures in this thread as I continue to work on the design, but I would really appreciate people's thoughts. As envisioned, the power jackshafts run centered in a carrier tube which is welded to the single arm rear triangles. Those carriers go through larger mount tubes which are an integral part of the frame.

So, please, opinions? Thoughts? Am I crazy?


Hmmm...for some reason this thing is refusing to open the "Manage Attachments" button bar.

Fixed that.

[srdavo]

here's a site with some info about leaning deltas...
scroll down the left side of the page & click on: Python Tilting Delta

http://www.fleettrikes.com/index.htm

I want to see more pics of what you're sketching..... maybe one of the whole trike?

[SimpleSimon]

Love that Fleet Trikes site. Lots of great stuff there.

I basically finished the APAXI desgn today - would have had it sooner but have been having eye troubles that make sketching difficult. Next up - same basic idea but wider/longer as a cargo bike.

I'm not terribly happy with the forks as drawn, but the eye troubles are preventing me from doing the really fine nit-picky detail work needed to draw springer forks. Naybe later, if the impending eye surgery fixes the problems.

Anyway, here's what I've got. I am no engineer, and am unsure this design is workable. The vector calculations to figure side loading tolerances on the swing arms pretty much ate my lunch - so badly I just added 50% to the materials strengths I arrived at to be sure the idea stays in range of do-able. I wish some of the better educated in engineering members would look at this thing for me.

Final footprint is 18" wide by 47.5 long on the wheelbase. Add 26" to that for overall length. or 73.5" long. Overall width is just 22".

[PatrickW]

What graphics drawing program are you using? It looks great!

[SimpleSimon]

Hmmm...I had written a reply to this earlier, wonder where it went?

Patrick (good name, by the way!) I use Google SketchUp, the latest free version. Great little program - if I could afford it I'd buy the professional version.

Patrick E.