double cranks

Unicycles and Equipment
1

I have my uni training grounds some half an hours ride away from home. On the trails I need long cranks, but using them to get there is tedious. So in order to ‘gear’ my uni I would need either cranks with multiple holes, or perhaps double cranks. Is there such a thing?

double-crank.gif

2

i’ve had a similar idea… but didn’t think through it and the plan had left my head

anyway, it looks like (from your picture) that it could be dangerous

3

you would have to switch the pedals though right? unless you have weird legs that could dodge a second set of pedals;)

4

i think that is why i dropped the idea in the first place :stuck_out_tongue:

edit: heres my original idea: (excuse my misuse of technical terms, i’m not all that mechanical, i just ride the damn things)
o=where pedals connect

  • = the crank (duh)
    0 = connection to the hub

o-o–0

and the other side would be opposite (duh): 0–o-o

5

you mean like
[img=http://img85.exs.cx/img85/889/unipedal9xi.th.jpg]

6

There would only be one set of pedals, how I understand it. The pedal would be on one end, and the crank would attach to the hub either at the center hole or the end hole.

7

This is perhaps an easier solution:

8

Here’s something I cooked up in about 5 minutes:

mini-uni crank.jpg
mini-uni crank.jpg535×640 60.1 KB

9

unisk8r’s coker “purple phase” has not only double cranks but triple cranks.

36geared.v2.frontboxsm.jpg
36geared.v2.frontboxsm.jpg480×640 59.2 KB

10

Oh yeah?

holeinone.gif

11

IMO a good priced adjustable crank would be a great bit of kit to have, giving the advantages of a geared uni without losing out on the mechanical simplicity that is such a nice aspect of unicycles.

http://www.unicyclist.com/forums/showthread.php?s=&threadid=30079

Is a thread which started with my own idea for an adjustable crank design and developed into a three page discussion with loads of great ideas and some very nice contributions from showard showing computer generated designs of the ideas (on page 2).

12

Thanks for the pointer and the red eyes reading that huge thread gave me. Very interesting thoughts and designs but taking all things in consideration like design and manufacturing problems I think I’ll start out by trying the ‘multiple pedal hole crank’ alternative. I don’t mind if it takes a minute to unscrew and move the pedals. I too want to keep the unicycle design simple. It’s just that on days when I do more than one type of riding I would appreciate the possibility to change from road to trail gear with short notice. Perhaps I just buy me a set of long cranks and take them to a shop where they can drill and thread a couple of extra holes in them.

13

Getting holes drilled and threaded wouldn’t be that easy. It is absolutely vital that the axis of the pedal spindle is perfectly parallel to the axis of the hub. Even a tiny variation will affect your riding comfort, and could conceivably cause injuries to your ankles.

I asked a friend who is an engineer to consider making me some custom length cranks. he said he could do it, but he’d have to make a special jig to hold it all perfectly in line.

Search the forum and you will find references to:
Multi-hole cranks
Telescopic (extending) cranks
Discs with multiple holes
Switchable gears.

The multi hole cranks and extending cranks are available commercially, but are expensive.

Better to compromise and select one set of cranks suitable for the ride, and to ride within the limits of the cranks you’ve chosen. The simplicity is part of the charm of a unicycle. Also, my own experiments have shown that short cranks make less difference than they ought to, except in very specific conditions. Read Aspenmike’s posts about 80 mile days on a Coker on 170s to see that short cranks are not the be all and end all of fast distance riding.