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Old 2003-06-11, 07:23 PM   #1
jason
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Lightbulb KH24 gets new cranks- Yippie!!!

Greetings,

Two weeks ago I replaced my standard KH splined cranks with a pair from DM Engineering.

You may have read on rsu that the KH splined cranks are not for everybody. This is mainly due to the fact that they have no Q in them whatsoever. If you unfamiliar with what a Q-factor is then you can find a clear definition here:

http://tinyurl.com/e1zy .

Because the KH cranks are perfectly stright some people (like myself) hit our heels on the cranks where they attach to the hub. More often than not this will cause a upd. I found that I had to place my feet perfectly on the pedals during a freemount or I would knock my heel and upd. To resolve this issue I had purchased some large pedals (Mosh) which allowed me to place my feet further out away from the cranks. This helped somewhat but was not the answer.

After bantering back and forth with users of rsu, I concluded (thanks to Frank A.) that there is only one set of 170mm cranks that will fit the KH24 8-spine hub. The DM Engineering cranks. Basically there are two reasons for this:

1) BMX cranks cannot usually be found in 170mm. They are typically only available in 175mm or 180mm which is just too long for a 24" unicycle wheel and average sized rider.

2) Most of the low-end splined BMX cranks are fluted for a 10 spline axle rather than the 8 used on the KH hub.

Now comes my delime... should I spend with shipping $230.00 (USD) for the DM crank arms or should I do as Frank has done and build or purchase a new Profile wheelset? I'm not much of a mechanic so building my own wheel is not likely, and buying a new Profile wheelset would set me back about $500.00 (USD). I decided to pursue the DM cranks.

The first thing I did was call Jordan at unicycle.com. Frank A. had mentioned that Jordan fitted the cranks to the KH hub, but I wanted to be certain they fit well before I put my money on the table. I was reassured by Jordan that they fit just fine but they would only be held on to the axle by the pinch bolts and not the end bolts. The spline flutes on the DM cranks run all the way through the cavity preventing the end bolts from fitting. The plastic collar on the bolts also prevent a fit but are easily removed. Using just the pinch bolts is fine from a tightness reliability standpoint, but I was concerned that water and grime would enter and settle in the axle's threaded cavity if the hole was not covered. Jordan thought the standard dust covers would fit so I purchased a pair but they didn't fit- (shaking fist) damn you Jordan!!

I wasn't going to let this spoil my fun so I installed the cranks anyway. First, I lathered the splines with a fresh helping of copper anti-seize to prevent creaking, then I slid the first crank arm on to the axle and tightened the pinch bolt. Look'n pretty sweet! I started to install the second crank arm but it was too tight to simply slide on to the axle. I remembered reading that the Profile cranks are difficult to slide on sometimes and that they had to be whacked on with a 'rubber' mallet and that's just what I did. It required very little striking force to get the crank arm in place. I tightened the bolt, put on the pedals and went for a test ride.

My neighbor is an aircraft machinist so I had him take a look at the end bolt situation. Originally I thought I would have him grind out the spline flutes to allow the end bolts to fit. Later I decided it would be better to go the other way, taking down the flange on the KH bolts instead. He agreed. Why not, after all the only purpose for the bolt is to keep mud and gunk out of the axle.

I've been riding with DM cranks for almost two weeks now and I really enjoy them. I've not hit my heel a single time on the crank and in my opinion the added Q-factor actually make riding more pleasant. The pinch bolts have adequately secured the crank arms to the hub and I've not had to tighten them at all. A strange observation is that the added Q seems to give me more torque for things like climbing hills. It could be that my legs are getting stronger or that I'm becoming more comfortable and accomplished with the unicycle. Either way I'm pleased.

If you have a KH24 and you're unhappy with the cranks there's an alternative for you- DM cranks. The plus side is that the DM cranks are solid, proven to work well and cost less than a Profile setup. On the minus side it's still an expensive solution. I think if I were capable of building my own wheel I would have spent $300.00 (USD) on the Profile hub and cranks instead. However, as I stated before I'm not much of a mechanic so I would have had to purchase a pre-built wheel for around $500.00 or have one built locally. This solution has worked well for me and I'm happy with it.

My neighbor still has the bolts. He was conservative when taking down the bolt's flange on the first run and needs to take a bit more off. When the bolts are returned and in place I'll take some photos and post them to the gallery site for anyone who would like to check it out.


Cheers,
Jason

----
If anyone knows of any other 170mm cranks that fit the KH 8-spline hub you should post about it. I'm sure there are others like myself looking for an inexpensive alternative to the KH cranks.
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Old 2003-06-11, 10:25 PM   #2
Frank A.
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Hi Jason,
I'm glad you've solved your dillema. We both took different paths but we have reached te same place, MUni happiness

There are other types of bolts for the axle end. If you can post a photo of the DM crank, I may be able to find something. The Big Cheese/ Specialized cranks have a bolt that may solve this problem. The flutes in the crank also extend throug the "barrel".
Congratulations,
Frank


(edit)
Jason,
Did you ask Uni.com if they had the bolts they use on the DM ATU cranks? It may be the same thread size as the KH axle, and if so, your problem will be solved. Did Jason try the DM bolt in the KH axle? I was only thinking about the spline pattern and didn't ask that myself when I asked him to try the cranks.
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Last edited by Frank A.; 2003-06-11 at 10:30 PM.
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Old 2003-06-11, 10:44 PM   #3
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Quote:
Originally posted by Frank A.
Hi Jason,
There are other types of bolts for the axle end. If you can post a photo of the DM crank, I may be able to find something. The Big Cheese/ Specialized cranks have a bolt that may solve this problem. The flutes in the crank also extend throug the "barrel".
Congratulations,
Frank
Hi Frank,

Ah yes, MUni happiness! Thank you for your offer. Here is a url to a DM crank image at unicycle.com, http://tinyurl.com/e3ai Are the threads in the axle the same as other similar splined axles or would they possibly pose a problem? The splines go all the way through the barrel and taper slightly on the ends. The diameter of the DM barrel is slightly smaller than the KH's. I can measure them if that helps?

Also, if your son wants a spare pair of 170's for his KH hub just let me know and I'll give them to him. I'm pretty sure that I have no use for them now.


Cheers,
Jason
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Old 2003-06-11, 11:13 PM   #4
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Hi,

I'm working on these cranks right now. The solution I'm probably going to go with is to keep zero Q-factor (ie zero outward flare) and move the crank arms as far out as possible on the pinch spline tube at the base of the cranks.

This would mostly get rid of the lip here without adding any Q-factor.

Q-factor is something that some unicyclists like and others don't like. The main advantage to minimal Q-factor is that it lowers the chance that your pedals will hit the ground when cornering, and having no Q-factor is usually better for freestyle.

Cool to learn that DM cranks fit this hub though- I didn't know that.

Opinions?

-Kris Holm
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Old 2003-06-11, 11:36 PM   #5
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Quote:
Originally posted by danger_uni
Hi,

I'm working on these cranks right now. The solution I'm probably going to go with is to keep zero Q-factor (ie zero outward flare) and move the crank arms as far out as possible on the pinch spline tube at the base of the cranks.

Opinions?

-Kris Holm
Hi Kris,

I am happy to hear that you're addressing the crank issue. I'm really enjoying my (your) Muni and I tried to adapt myself to the crank design but just couldn't do it.

Moving the crank arm further to the outside edge of the barrel lip would probably solve much of the heel strike issue but now that I have experienced a higher Q-factor I find it personally favorable. I really like the way the DM cranks feel. However, from a production stand point moving the crank arm outward would be a much simpler and less expensive solution to redesigning a new crank style. On the other hand, I think that a more BMX looking crank (Profile like) would make your unicycle more marketable. There's a certain comfort that comes with familiarity.


Cheers,
Jason
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Old 2003-06-12, 06:48 AM   #6
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Quote:
Originally posted by danger_uni
Hi,

I'm working on these cranks right now. The solution I'm probably going to go with is to keep zero Q-factor (ie zero outward flare) and move the crank arms as far out as possible on the pinch spline tube at the base of the cranks.
I would prefer to have a little bit of outward flare for a muni crank. The outward flare is more ankle friendly and the wider stance is actually better for muni and trials. The wider stance is more stable when hopping and also gives you more turning control.

For freestyle, for track racing and for a high RPM road riding I'd vote for straight cranks and minimal Q-factor. But for muni and trials I vote for a little outward flare in the cranks to be more ankle friendly and the additional Q-factor is actually a bonus.
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Old 2003-06-12, 09:26 AM   #7
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Quote:
Originally posted by danger_uni
The solution I'm probably going to go with is to keep zero Q-factor (ie zero outward flare) and move the crank arms as far out as possible on the pinch spline tube at the base of the cranks.

This would mostly get rid of the lip here without adding any Q-factor.

Q-factor is something that some unicyclists like and others don't like. The main advantage to minimal Q-factor is that it lowers the chance that your pedals will hit the ground when cornering, and having no Q-factor is usually better for freestyle.
I'm confused by Kris's use of the term Q-factor which is different from the explanation referred to by Jason's first post in this thread. The latter is how I understand Q-factor: distance between the outside of the cranks at the pedal hole (I read that as left-right distance component only).

In that latter definition of Q-factor, it doesn't matter how that distance is achieved, by flaring the crank outward or by placing the cranks further to the outside without altering their shape. The choice between these two options would make a difference for the change that your heel hits the axle (which is the issue with the KH cranks) but it would make no difference for the other issues related to Q-factor.

Any comments?

Klaas Bil
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Old 2003-06-12, 06:28 PM   #8
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Re: KH24 gets new cranks- Yippie!!!

Klaas Bil wrote:

> danger_uni wrote:
>
> In that latter definition of Q-factor, it doesn't matter how that
> distance is achieved, by flaring the crank outward or by placing the
> cranks further to the outside without altering their shape.
>
> Any comments?



Klaas,

You have a good point about the Q-Factor, "it doesn't matter how the
distance is achieved". In that light I would like to say that the
"flared" option would be preferable from the standpoint of achieveing
both Q and to prevent striking your ankle on the crank when doing trials
style riding.

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Old 2003-06-12, 06:50 PM   #9
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Quote:
Originally posted by Klaas Bil
In that latter definition of Q-factor, it doesn't matter how that distance is achieved, by flaring the crank outward or by placing the cranks further to the outside without altering their shape. The choice between these two options would make a difference for the change that your heel hits the axle (which is the issue with the KH cranks) but it would make no difference for the other issues related to Q-factor.

Any comments?
your absolutly correct,the Q on the cranks is going to be wider if the crank arm is moved to the outside like Kris says,it will also be wider if it is left where it is but flared out.

the Q would be really wide if the crank arm was moved and flared.

i would not just flare them,even if they are flared that pertrution is still going to get a few ankles.i think the best thing to do is like KH said,move the arm out so the its flush with the fixing bolt.
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Old 2003-06-13, 01:13 AM   #10
jason
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Images of KH24 with DM cranks

Here is a link to images of my KH24(tw) with DM cranks.

http://tinyurl.com/e72y
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Old 2003-06-13, 01:20 AM   #11
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Quote:
Originally posted by jagur

i would not just flare them,even if they are flared that pertrution is still going to get a few ankles.
Jagur,

I'm not sure this is correct. I compared side-by-side the crank barrel protrusion of the KH cranks to the DM cranks and they appear to be indentical or very, very close. The "flare" of the DM cranks shortens the protrusion by passing through it on that side of the crank where it flares.

<edit>
You can see this if you look at my posted images.
</edit>

Whew! That was a mouthful. I have had no problems with DM cranks and lots of problems with KH stock ones. I vote for flare!

Last edited by jason; 2003-06-13 at 01:25 AM.
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Old 2003-06-13, 01:56 AM   #12
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Re: Images of KH24 with DM cranks

Quote:
Originally posted by jason
Here is a link to images of my KH24(tw) with DM cranks.

http://tinyurl.com/e72y
Nice. I also like that you've added some mojo to your muni.

I have DM cranks on my Vortex muni and have had no problems with the cranks hitting my ankle. In that regard, crank flare is a good thing.

Just to clarify. I was picturing moving the crank arm as far out on the pinch spline tube as Kris suggested along with a little bit of flare.

And Klaas is correct. But bike people are often very sloppy in their use of what they call Q-factor. Sometimes they talk about the Q-factor of the bottom bracket spindle, sometimes they talk about the Q-factor of the cranks (how much the cranks flare out), and other times they are talking about adjustable Q-factor in the pedals. You have to look at the context of what they're talking about to figure out what they mean by Q-factor.
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