Crazy Arms

I know that the idea of having crank arms on a Coker that are adjustable in length isn’t anything new. But here is my take on the idea.
I made up a set of cranks that adjust by a quick release lever on each crank so that an arm at the end of the crank can rotate to different length settings. Because the main crank arm is concentric, and the adjuster arm is excenteric (crazy) the 1956 C&W song “Crazy Arms” is stuck in my head now.
Crazy Arms Video
I rode about 25 miles with them on Friday, they realy make hill climbing a breeze when set at the max length 165mm and then I can realy cruise along on the flats with them set at around 120mm and on rolling terrain set at around 145mm.

Al :O)

That is a very interesting idea, and I think it would work really well. The only possible negative side is if the quick release comes loose while you’re riding…that might turn out badly. But still, I like it!
Also, it would be cool if there was some way to do it while you’re riding, but I don’t see how that could work…

that’s beautiful!

has the quick release ever quickly released? i think i simple rubber ring type to hold it to the crankdealy would act as a safety device (is a safety device even needed?)

do you plan on mass producing these?

or semi-mass producing them?

or taking orders?

Can we see some pictures?

There’s a video linked in Al’s post.

Supremely AWESOME design! I’m eager to hear how this develops over time and how it holds up after an extended period of riding.

I don’t believe an accidental quick release would be too catastrophic on this thing… I mean, the pedals aren’t going to just fall off, or will they?

The one drawback I see to this is… those quick-release levers look HUNGRY for a shoelace or something else to snag…

What a cool looking setup, Al. Are the joints serrated so that they can be indexed and locked somewhat or do you just eyeball the settings to get the left and right crank length equal?

Oops, maybe I should take a look at that. Ha ha.

So… have you tried riding with one side at 120 and the other at 165 yet?:stuck_out_tongue:

i rode a coker with 110 on the right and 175 on the left, it’s actually pretty easy

The joint is a hex shaft that inserts into a 13/16" 12 point socket. There are 7 settings 115,120, 130,145, 160 & 165mm. The length incriments are not evenly spaced because the crazy arm rotates in 30deg. incriments.

I have the release levers laying back so if they snag they will be pulled closed, not open. A big fat rubber band would’nt be a bad idea though.
I have intentionaly ridden with the levers partialy loostened to see it they would walk out. They squeaked like crazy but after 2 1/4 miles were still fully inserted. So there would be plenty of warning before a catastrophic pedal detachment would happen.

As for production, I have given up on the Idea that I can make my fortune welding together unicycles. After the 30 mile Tour de Cure ride Ill post how they are holding up. And if there is some interest I may batch up a couple of sets.

That’s even stronger than serrated faces and certainly more clever.

Ingenious! Simple and effective - what good design is all about in my book!

sweet dude! ypu made them yourself? thats awsome! i wanna learn to fabricate stuff someday.

good luck!

by the way… you should get it a copyright on that!

those are a really cool idea, i definately buy some