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Old 2014-10-03, 02:36 PM   #31
Eric aus Chemnitz
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It has never been an issue. The spacer is just to save the axial position of the crank so that you do not have to adjust your caliper when crans begin to wear out.
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Old 2014-10-03, 03:20 PM   #32
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according to one of germanys biggest unicycleshops (einradladen.com) it is an issue because you need spacer where the crank is pressed against with the crankscrew. Actually the crank should be force- and formfitting the axle.
You're talking about a spacer between the crank and the bearing, which is standard for all ISIS uni cranks, and is actually required to make uni hubs meet the ISIS standard (which has a hard stop in it in order to fix the location of the cranks)? ISIS cranks of any variety should not be fitted without a spacer behind them (except on a Schlumpf hub, but then that doesn't meet the ISIS spec), as ISIS is not designed to work with the taper stopping the crank. See http://www.isisdrive.com/isisdrive/I...ument_revD.pdf

I'm not sure how this is an issue.
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Old 2014-10-03, 06:13 PM   #33
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Wheel strength. no difference between the dished and non-dished wheels in reality.
Roger, I respect you and the work you do, but I gotta differ with ya on this one.

Dished wheels are less stable laterally than symetrical builds. It's not a big deal on small wheels and wide rims, but it becomes much more obvious and critical on large wheels and narrow hubs.

This is the reason that rear hub spacing has increased on mtb's to 150/170/190mm, to increse wheel strength.

It was mostly for the above reason that I went to an external rotor.
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Old 2014-10-03, 06:43 PM   #34
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Roger, I respect you and the work you do, but I gotta differ with ya on this one.

Dished wheels are less stable laterally than symetrical builds. It's not a big deal on small wheels and wide rims, but it becomes much more obvious and critical on large wheels and narrow hubs.

This is the reason that rear hub spacing has increased on mtb's to 150/170/190mm, to increse wheel strength.

It was mostly for the above reason that I went to an external rotor.
What size rim is considered wide? So you are saying that the Oracle hubs are not wide enough for it's dished wheel? Is there an inboard system that you would use if it was available for a unicycle?

I'm asking because I'm considering a 29" Unicycle for mostly road use.
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Old 2014-10-03, 06:58 PM   #35
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Originally Posted by Nurse Ben View Post
Roger, I respect you and the work you do, but I gotta differ with ya on this one.

Dished wheels are less stable laterally than symetrical builds. It's not a big deal on small wheels and wide rims, but it becomes much more obvious and critical on large wheels and narrow hubs.

This is the reason that rear hub spacing has increased on mtb's to 150/170/190mm, to increse wheel strength.

It was mostly for the above reason that I went to an external rotor.
The move to the 170/190 spacing is mostly on fat bikes. Dishless wheel strength is a benefit, but the primary reason is chainline. The rear cassette needs to move outboard so the chain can remain as straight as possible and still clear the rear tire.

On the disc side, a uni with an inboard disc is still in the realm, dish wise, of what has been acceptable in the biking for a very long time.

In theory, yes, the dishless wheel is stronger. Up to a 29 in the uni world I can see Roger's point that there's not much of a practical difference. I don't think I'd be keen on a 36" inboard disc 100mm wide wheel. The move to the wider spaced hub makes sense there for sure.

All of my disc braked unis are outboard- not because I don't see inboard as a viable option, but many of them were retrofit and I didn't want to rebuild wheels.

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Old 2014-10-03, 09:06 PM   #36
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Originally Posted by aracer View Post
You're talking about a spacer between the crank and the bearing, which is standard for all ISIS uni cranks, and is actually required to make uni hubs meet the ISIS standard (which has a hard stop in it in order to fix the location of the cranks)? ISIS cranks of any variety should not be fitted without a spacer behind them (except on a Schlumpf hub, but then that doesn't meet the ISIS spec), as ISIS is not designed to work with the taper stopping the crank. See http://www.isisdrive.com/isisdrive/I...ument_revD.pdf

I'm not sure how this is an issue.
It doesnt have to be an issue. If the crank doesnt sit coaxial on the axle, because of tolerances the disc will oscilerate. The spacer can ensure the axial position of the crank but not really the coaxiality like the planed male shoulder of the isis drive. Thats what I meant...
If it works fine, its no issue... If the tolerances are miserable it could be an issue. Its much easier to get an inboard disc mount coaxial to the turning axle..
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Old 2014-10-03, 10:19 PM   #37
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On the disc side, a uni with an inboard disc is still in the realm, dish wise, of what has been acceptable in the biking for a very long time.
But bikes split the load over two wheels; unicycles are loaded double in comparison. And bikes don't normally have much side loading, whereas I'm always offcenter on my uni wheel, whether it's balancing at a standstill, doing corrective hops, landing drops - unis are a lot more demanding.

My Oracle wheel has held up OK, but I'd be happier if it were symmetrical, even if it were just by having the rim drilled offcenter. As it is, the disc side spokes don't have much bracing angle, the offside spokes are pretty low tension, and they are always creaking and fretting against each other, indicating a lot of rim movement.

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Old 2014-10-04, 12:16 AM   #38
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It doesnt have to be an issue. If the crank doesnt sit coaxial on the axle, because of tolerances the disc will oscilerate. The spacer can ensure the axial position of the crank but not really the coaxiality like the planed male shoulder of the isis drive. Thats what I meant...
If it works fine, its no issue... If the tolerances are miserable it could be an issue. Its much easier to get an inboard disc mount coaxial to the turning axle..
The spacer does exactly the same job as a machined shoulder on a bicycle ISIS BB, I'm not sure why you think there would be a difference. This also appears to be a purely theoretical issue which nobody has actually found a problem with.
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Old 2014-10-04, 11:26 AM   #39
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Originally Posted by imkreisdreher View Post
... If the crank doesnt sit coaxial on the axle, because of tolerances the disc will oscilerate. [...] If the tolerances are miserable it could be an issue. Its much easier to get an inboard disc mount coaxial to the turning axle..
In which time do you think we live? It's absolutely no problem to produce cranks where the ISIS interface and the thread pattern for the rotor are coaxial and it would also heve been no problem 20 years ago. There's even more play in the six holes of the rotor than tolerances of the crank are. Maybe this would be an issue if you hand file the crank from a block. But these are cnc machined parts. And why the hell schould miserable tolerances be an issue at the cranks when they aren't at the hub? Why should a hub be machined more precisely than a crank? Don't be mad at me, but this arguement seem to be totally bullshit to me ...
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Old 2014-10-04, 12:57 PM   #40
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In which time do you think we live? It's absolutely no problem to produce cranks where the ISIS interface and the thread pattern for the rotor are coaxial and it would also heve been no problem 20 years ago. There's even more play in the six holes of the rotor than tolerances of the crank are. Maybe this would be an issue if you hand file the crank from a block. But these are cnc machined parts. And why the hell schould miserable tolerances be an issue at the cranks when they aren't at the hub? Why should a hub be machined more precisely than a crank? Don't be mad at me, but this arguement seem to be totally bullshit to me ...
Does that sound like there are no problems with tolerances: http://www.unicyclist.com/forums/sho...&postcount=104

Oh and btw please stay objective and dont get personal.

I am out...
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Old 2014-10-04, 02:35 PM   #41
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Does that sound like there are no problems with tolerances: http://www.unicyclist.com/forums/sho...&postcount=104
I think this are two different things. The one is, drilling six holes for the disc brake mount concentrical to the ISIS interface, which is - for modern manufacturing - no problem. The other thing is producing an ISIS interface into the crank which is much more complicated. But an ISIS interface with a too narrow cone schould not affect the concentricality of the disc mount to the axle.
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Old 2014-10-05, 02:16 AM   #42
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I prefer the inboard disc.

I just have the one uni these days though - the fat tired Oregon. On a wheel build as wide as the Oregon I doubt the dishing makes any practical difference.
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Old 2014-10-05, 04:12 PM   #43
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Does that sound like there are no problems with tolerances: http://www.unicyclist.com/forums/sho...&postcount=104
It sounds like somebody was using ISIS without a spacer, relying on the taper stopping the crank (which it isn't designed to do) and wearing the crank by pushing it too far onto the spindle.
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Old 2014-10-05, 04:57 PM   #44
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Roger, I respect you and the work you do, but I gotta differ with ya on this one.

Dished wheels are less stable laterally than symetrical builds. It's not a big deal on small wheels and wide rims, but it becomes much more obvious and critical on large wheels and narrow hubs.

This is the reason that rear hub spacing has increased on mtb's to 150/170/190mm, to increse wheel strength.

It was mostly for the above reason that I went to an external rotor.
Yes, a non dished wheel is stronger, that is of course correct.

As a unicycle shop we get to see returns and repairs... and we are not seeing any significant difference.

Some of this may be because we have not pushed the boundaries and the dishing is not as extreme as you see on many bikes. The exception is the 36" wheels where you have movement in the rims with narrower hubs, hence the wider bearing pitch on those wheels to allow for that putting them at the similar angles the smaller wheels.

Roger
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Old 2015-12-17, 04:05 AM   #45
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Con?

When packing a unicycle for airplane travel should the rotor be taken off? If so, is it a hassle to take off an internal disc rotor?
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