Newbie question: How can crank length affect speed?

[Jesper]

Hi all

Actually I'm more like a pre-newbie since I'm only in the process of ordering my first uni, a 24" muni. I've wanted one since I first saw a video of Kris Holm.

I've been following this forum for some time and I've often read that shorter crank are supposed to give higher speed. I don't really understand how that can be? Since the cranks are attached to the wheel axle, the only way to increase speed is to increase cadence, which should be independent of crank length. The only explanation I can think of is, that the smaller cranks makes it easier to maintain a higher candence?

Jesper

[saskatchewanian]

Originally Posted by Jesper

The only explanation I can think of is, that the smaller cranks makes it easier to maintain a higher candence?

Jesper

Exactly

With shorter cranks your feet don't move as far per rotation (with relation to you and the unicycle) as with longer cranks, making it easier to spin faster for longer. Of course there is a tradeoff, with the shorter cranks you can't put as much torque to the wheel and loose some element of control.

Check out this thread of more info than you ever wanted to know about wheel size/crank length interactions.

Total Gear Ratio (I still think it should be Total Gain Ratio)

[Mikefule]

http://www.unicyclist.com/forums/sho...eed+hypothesis

[Tincher Teach]

I am a newly returning uni enthusiast. It's been forty years, give or take, since my last ride. I have been following this forum for about a week and understand many of you have a deep respect and love for uni's.

In relation to crank length, I have noticed the term Q factor. Can someone please enlighten me on this term.

I have also just order a Nimbus Oregon (I know that seems like an extreme purchase for having been away for so long) for use around my beach town and in the mountains. I've noticed that there are cranks with dual holes at 125 and 150, I believe. Would these be useful on the Oregon?

[saskatchewanian]

Originally Posted by Tincher Teach

I am a newly returning uni enthusiast. It's been forty years, give or take, since my last ride. I have been following this forum for about a week and understand many of you have a deep respect and love for uni's.

In relation to crank length, I have noticed the term Q factor. Can someone please enlighten me on this term.

I have also just order a Nimbus Oregon (I know that seems like an extreme purchase for having been away for so long) for use around my beach town and in the mountains. I've noticed that there are cranks with dual holes at 125 and 150, I believe. Would these be useful on the Oregon?

Q factor is the width or the cranks and hub combined, dictating how far apart your feel are when you are pedaling.

The Oregon has a super-wide hub which gives it a high Q-factor compared to other unicycles. Using the KH dual hole cranks will push the pedals even further out than you would have with the cranks that come standard on the Oregon.

Some people like a wider stance than others than others so that might work for you. Generally most people like a bit more Q when riding MUni/Trials than they do for freestyle or road riding. A wider stance can help with control while going slow but can also contribute to wobble at speed.

[Tincher Teach]

Thanks Saskatchewanian,

So then, would it be useful, if I installed the KH dual hole cranks, to move from the 150 position to the 125 position at any point during a ride? I'm 6' 1" tall. Also does it make since to switch out the cranks back to the originals or is this something I'm just gonna have to figure out on my own?

[saskatchewanian]

Everyone is different, you pretty much need to experiment and find what works for you.

[skilewis74]

To me the consensus seems to be that it's usually not usefull to swich positions in the middle of the ride, although relatively easy and just a couple of minutes to do.

If you are several miles from the trial you could ride on the road @125 then switch 150 at the trailhead. Or if you have all easy flatish trails but stop to do some trials on the side of the trail it'd be good to switch the longer position.

Edit: closer lengths would be more useful on the trail, like you get the 150's and get them drilled closer, like 130.

[Nurse Ben]

Teach, the Oregon is a very big wheeled uni, so trying to ride with shorter cranks is going to be tough as you will have insufficent leverage (torque). Also, as already stated, the wider spindle on the Oregon would be compunded by a crank with more Q, like the dual hole Moments. One Oregon rider is using 150's and said it was fine, so maybe that'd work for flatter riding like you have at the beach. Mine is set up with 170's, they come stock with 165's.

Try ordering some Voyager 150's and swap back and forth, then see which you like best. Due to the sheer size of the Oregon and the Larry tire, it really is a dedicated muni, not a uni that'll crossover for road use. I have considered getting a 29er wheel built up for XC use, but it's so wide that I'm no sure it's worth the effort.

I fall into the long crank camp cuz I love to climb steeps and short cranks just don't work, but this does make spinning more jerky and probably slows me down. Also, long cranks make downhills easier and increase control.

[Tincher Teach]

Thanks Ben,

I'll take your advice and see how things work out as stock for a while. Still trying to figure out the finer details of riding gear now-helmet, gloves, shoes and the like. I have some KH leg armor coming with the Oregon. Any input on the above would be greatly appreciated. Kind of curious about what odds and ends to carry on a ride as well. Thanks again.

[saskatchewanian]

For riding gear I would strongly recommend the KH wrist guards. They let your wrists and hand move a bit more than most which can mean less broken fingers from over stiff guards, besides they are fairly comfortable.