two sprockets

It’s been forever since I’ve posted (nearly a year) and I’ve gotten back into unicycling lately. I’m planning on building a giraffe muni. I’ve got it all figured out, but I can’t figure out how they get the sprockets for both chains on each side of the wheel. If you couldn’t follow my wording, here’s a link to someone who did what I’m talking about.
http://members.tripod.com/~derek_b/mgir.htm
Can’t figure out the two chain thing! :angry:
Thanks for the help!

I did some more reading around, and I stumbled upon this
http://www.tux.org/~bagleyd/unicycle_factory/sprockets.html
would the sprockets in picture #4 work, or is there something special that needs to be done to the wheel in order to do this? (sorry if this is amature type stuff. I just ride, but I am clueless to how everything works)

a flip flop pike hub might work. although dont know where youd get the cranks

Have you looked at Tandem bike parts as some of them have chainwheels on both the left and right handed cranks

jim

UDC makes a good dual chain giraffe. It’s currently out of stock. Don’t know when they’ll make another batch.

If you want to build one yourself then one option for the dual chain is to use a fixed gear hub that has a disk brake mount. Drill a cog to fit the 5 hole disk brake mount. The cog bolted to the disk brake mount will not come unscrewed while riding. Very secure, very safe. Just takes some custom machining to drill the 5 bolt holes in the cog properly centered and spaced.

You should be able to find cranks and a bottom bracket (mid bracket?) that will let you put chain sprockets on both sides. BMX bike components often come now with options for left hand drives so you can find BMX cranks that will accept a sprocket on the left crank. There is also the option of tandem bike cranks. Tandems have sprockets on the left hand side.

I sopose you would use a tandem back crankset, and a dualsided track rear hub.

Are you building the frame yourself?

No, I’m more or less modifying a Torker TX with a new wheel and all. Thanks for the help you’ve all given me, though! I think I may have an idea how it’s going to work now.

Why two chains? It might be hard to make it work on an existing giraffe, so be prepared for lots of custom work. Your crankshaft and hub, at a minimum, will need to be custom.

I don’t have much experience with double-chain giraffes myself. I think they are more about looks than anything else, though there is the obvious redundancy if a chain fails (which can be dangerous if it’s in mid-trick or mid-show). On the downside, you have to deal with twice the greasiness (something to consider for car transport and pants legs), twice the chain tension adjustment, and the possibility of one chain becoming longer than the other, making proper tensioning impossible.

Well I guess that that makes sense because mountain bikes only have one chain. Or would it be too much stress on just one chain because its direct drive, not geared?

Double-chained giraffes are much stronger than single-chained giraffes, tensioning the chain on a single-chained giraffe is like tightening the string on a bow and creates a lot of one-sided forces on the unicycle. You can feel this bow-like effect if you try bunny-hopping on a single-chain giraffe

Although double-chained giraffes are harder to produce as there is less tolerance on sprocket alignment, once it is set up correctly having two chains eliminates the slack spots you can get on single-chain giraffes and the slack you can get when idling on a single-chain

Having two chains makes a stronger machine which is more pleasant to ride

It is not really comparable to a mountain bike as you are not balancing on a pole above a single fixed wheel when you are on a bike

Giraffe chains do not need a lot of oiling as they are not ridden outside in unpleasant weather (or close to the ground behind a front wheel spraying up dust or mud) like on a bicycle. A light oiling is sufficient and wipe off the excess with a cloth, the chain shouldn’t need to be greasey.

jim

Does anyone have links to where I could get or look at any of the parts above? I’ve been searching and searching with no luck. To save you the time of reading through, the parts listed are a flip flop pike hub, tandem cranks, a fixed gear hub with a disk brake mount, and a dualsided track rear hub.

P.S. Sorry if I’m making this thread longer than it should be, I just want to get everything right.