If not, why?
I need 150mm cranks with Q-Factor. They cost $25. But shipment is $45 (to Lebanon where I live). I am wondering if it is possible to use ordinary bicycle cranks with Q-Factor, if I can find them at a local bicycle shop.
It is definately possible depending on the cranks. What kind of hub do you have? Ie: Isis splined, cottered.
Well, the hub is square. It is cottorless. I don’t know much about the terms ‘ISIS’ and ‘splined’ though.
Isis splined is the standard used on unicycles and some bikes. Its basically the universal spline that they use so that you can use different brands cranks on there cohorts unicycle brands.
You most likely will be able to find the cranks you need at your LBS (Local Bike Shop).
Take your unicycle to your LBS and see what they have or can get from their wholesaler.
You will almost definitely have a spider (arms for the chainring) on one crank, and they will probably be too long (I’m guessing 170mm) with no options for length (unless they’re for a kid’s bike),
If you have a bike shop around that does a fair bit of tandem work they will probably have the length you need in kids tandem cranks. Just don’t buy two left crankarms as one will have an annoying problem of the pedal unscrewing as you ride.
Yes, a bike shop is likely to suggest two left cranks, since they assume unicycles don’t get much action. But the pedal will tend keep coming loose, unless you use some sort of extreme (possibly destructive) methods to attach it more permanently.
What do you need wide cranks for?
For a unicycle you need a left and a right crank but bicycle cranks generally have a chain ring on the right hand crank. It is important that you don’t use two lefts as then the pedal on the right hand side will have the tendency to unscrew as you ride (plus you will need two left pedals as the left and right pedal are threaded differently to match the left and right cranks).
Some brands of cranks have a bolt on chain ring which can be easily removed. You then need to see whether the “spider” that the chain ring bolts on to will get in your way. You may be able to remove the spider and/or chain ring with a hacksaw or angle grinder.
Note that the front right crank of a tandem bicycle doesn’t have a chain ring on it, so if you find a bike shop that deals in tandems you can then get a right crank that will work for you, assuming you can find a matching left crank of the same length and Q factor.
The other big barrier to using bicycle cranks is that they tend to be much longer than unicycle cranks. It is rare to find decent quality cranks shorter than 165mm, so finding 150mm cranks could be tricky.
Another option to consider if you have access to engineering tools is to take two long left hand cranks, cut them down to size and get new threads cut at the 150mm mark. This is only worth considering if you have the know how to do it yourself or you have a friend/colleague who can do it for you on the cheap.
ISIS is a very new standard. Most good new unicycles will have an ISIS hub, but most cheaper new ones and certainly most unicycles over a couple of years old will have square taper.
You’ve still got a lot of unicycles out there with KH 8 splined and Onza 30(?) splined hubs. As well, of course, some very very old unicycles with cottered cranks - although most of these are probably now in John Foss’s garage 
So, whilst ISIS seems to be the way that the standard is going, it’s certainly not safe to generalise that if its a unicycle it has an ISIS hub.
To answer the OPs original question (even though it’s been fairly thoroughly answered already), Yes. And here’s a photo of the kind of thing you’ll end up with;
STM
Thanks for the photo. A picture is worth a thousand words! I don’t think the spider would cause any problems, would it?
I need them because with my regular 152mm cranks I am experiencing knee friction with the top of the frame. With wide cranks my knees would be placed wider apart so that there would be no such problem.
I could also use a wider pair of cranks. My Nimbus 36er has a very narrow ISIS hub. I noticed last week that I was riding sort of bow-legged, with my knees out to the sides. I’m sure this can’t be good riding form.
Any suggestions for ISIS cranks with Q-factor?
These cranks have a significant Q-0factor:
I don’t see that it should cause any problems. Even with a chain ring on it, it doesn’t affect bike riders. Having said that, though, I haven’t ridden a unicycle with one* so can’t offer any guarantees… but as mentioned earlier, you can always take a hacksaw to it.
STM
- Well, except for giraffes.
But they’re not ISIS.
But Luderart said,
“Well, the hub is square. It is cottorless. I don’t know much about the terms ‘ISIS’ and ‘splined’ though.”
They can catch on your trouser leg if you ride wearing long pants. If you ride wearing shorts I doubt you will notice a spider. If you are worried about aesthetics then half an hour with a hacksaw and a file would be all you need to remove the spider arms on an aluminium crank (aluminium is a pretty soft metal).
How long have you been riding?
Knee friction sounds like a new rider issue to me, please correct me if I’m wrong, but when I was a new rider I had all kinds of rubbing issues with my knees and feet. At that time I wanted the biggest Q factor possible, but now that I’m experienced I prefer no Q factor since I want my feet to be as close as possible to the hub to reduce the outward lean that can be destabalizing when spinning.
I’d suggest using a standard crank and learning to ride differently or consider changing your armor (if this is what’s rubbing) so that you reduce the interference. What frame do you ride? This could also be an issue as some frames are wider at the crown.
A small change in Q factor won’t have much effect as it only moves the pedals out a very small amount (1/8-14"). You’d have more luck by widening your stance, i.e. moving your feet outwards on the pedals.
Knee Friction
I have three suggestions.
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Put your feet farther out on the pedals. moving them out by 1 centimeter might be all that you need to avoid the knee hits on the fork. Much cheaper than new chranks.
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Buy a KH unicycle. KH unicycles have nicely rounded forks. Even if you do hit the sides of your knees on them it does not hurt.
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Keep on riding. Lots of problems tend to work themselves out with time.
There is a huge variety of bicycle cranks. Many different designs. Since unicycling I have been looking closely at bike parts too. Although rarer there are bicycle cranks that are semetrical. I don’t know how much of an effect the cranks with the wide chain sprocket attachments will have on unicycling. They will make the unicycle unsymetric though.
Unicorn
About 2 months. And I still have to learn to do it properly. The change to the shorter cranks (127mm) also slowed my progress. And I get to practice only one-two days per 1-2 weeks since I keep my unicycle in our mountain home.
Thanks for the advice. But do you mean to suggest that I consider changing the frame to a narrower one instead of changing the cranks to ones with Q-Factor? I think it is much more practical and cheaper to change the cranks!
If I move my feet outwards on the pedals, part of my feet will rest outside the pedal area. Would that be a safe way to ride?