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Wheel Dishing
#1
Is the rear wheel on a bike properly dished if the rim is equally distant from the frame? I trued my rear wheel a little today, and I'm wondering if I need to go any further to check if it's centered than measuring the distance between the rim and the frame on either side of the wheel.
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#2
A wheel is properly dished if the outer face of the lock nuts on each side are the same distance from the edge of the rim on the same side.

One way to check, is to place three soup cans or similar of the same size and height on a flat surface, arranged in a circle of the same diameter as the rim. Put the wheel down on the soup can, measure the distance from the lock nut face to the flat surface. Turn the wheel over, and repeat. Your two measurements should be the same within less than 1mm.

I built a truing stand: http://forums.bicycletutor.com/thread-3834.html with which I use a center zero stainless steel ruler for find the center and guage the dish of the wheel.
Nigel
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#3
(01-22-2015, 02:11 AM)nfmisso Wrote:  A wheel is properly dished if the outer face of the lock nuts on each side are the same distance from the edge of the rim on the same side.

One way to check, is to place three soup cans or similar of the same size and height on a flat surface, arranged in a circle of the same diameter as the rim. Put the wheel down on the soup can, measure the distance from the lock nut face to the flat surface. Turn the wheel over, and repeat. Your two measurements should be the same within less than 1mm.

I built a truing stand: http://forums.bicycletutor.com/thread-3834.html with which I use a center zero stainless steel ruler for find the center and guage the dish of the wheel.
O.K., that sounds like a good, easy way to check dishing if the wheel has been removed from the bike, and next time I take the wheel off I'll do that.
Just for a general understanding of the concepts involved though, the distance between the frame and the rim should be about the same on either side if the frame isn't bent or anything, right? I'm not just being lazy, I'm wondering how I 'might easilly tell if something's wrong with the wheel just by looking, or with a very simple measurement.
I guess another related concept would be, if the frame were bent, which would be more important, centering the wheel in the frame, or dishing it properly? I would guess the dishing, since it would affect spoke tension.
These are more or less general questions, as I said, I don't think anything's wrong with the wheel or the frame.
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#4
I'm no expert, having learned about Dish and Soup Cans in past few months....
Soup Can (for Me) verified that Dish was correct.
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#5
(01-22-2015, 12:29 PM)JanJ Wrote:  I'm no expert, having learned about Dish and Soup Cans in past few months....
Soup Can (for Me) verified that Dish was correct.

That's cool, I'm not an expert either, that's why I asked, thanks for your reply!
So, my question to you would be why did you check the dish of the wheel? That's more or less the point of my question, if you catch my drift. What should a properly dished wheel look like? What sign would there be your wheel wasn't dished properly that you could feel just by riding the bike?
What does dishing do, and how much should I know about it in order to keep my bike in good shape if I'm just an average rider?
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#6
Dishing is done so that a wheel will be in the center of the frame, so it tracks correctly. Yes, if the frame is straight a properly dished wheel will be centered between BOTH the seat stays and chain stays. You don't change dish to accommodate a bent frame, and dishing is done only for centering, not for spoke tension. Dishing will not change much unless someone trues the wheel from only one side of the rim.
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#7
(01-22-2015, 03:01 PM)cny-man Wrote:  Dishing is done so that a wheel will be in the center of the frame, so it tracks correctly. Yes, if the frame is straight a properly dished wheel will be centered between BOTH the seat stays and chain stays. You don't change dish to accommodate a bent frame, and dishing is done only for centering, not for spoke tension. Dishing will not change much unless someone trues the wheel from only one side of the rim.

Thanks!
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#8
I was doing much needed grease & bearing replacements on 1970 French bike.
When I re-did rear bearings, I loosened both sides, which I now know was wrong, but.... I found spacers possibly wrong and I attempted to 'fix' it.
When I posted what I did here, I was directed via many steps, as to the proper way to space out things on an axle. Ended up doing a lot of measuring and spacer movement. I believe It was incorrectly set up, and I made it much worse. Chain Alignment was off
As I learned the terminology of the items I was adjusting, and one intense evening of measuring and doing math to attempt to space it correctly..... And I re-built the axle spacing one more time... and got to where I thought it was good..... At least mathematically...
It was then, after it was back together and hopefully correct that "DISH" came into the conversation... as a rim correction to the hub spacing correction... so to speak....
Simple test... I flipped wheel around, and it seemed to be nearly identical....

It was then someone mentioned "Soup Cans" approach, which again needed description... I then tried Soup Cans approach, and that measurement agreed within .6-.7 MM of the measurement I got from the mathematical approach.... and at that time I called it "OK", and put the wheel back on the bike... I did get in a 5 min ride before the snow and cold came... and during that ride it rode fiine...
Ask me again in Late April or May! Smile!

So yes, I used Soup Cans to verify that the mathematical spacing and Dish was OK.



(01-22-2015, 01:33 PM)J. Hanley Wrote:  
(01-22-2015, 12:29 PM)JanJ Wrote:  I'm no expert, having learned about Dish and Soup Cans in past few months....
Soup Can (for Me) verified that Dish was correct.

That's cool, I'm not an expert either, that's why I asked, thanks for your reply!
So, my question to you would be why did you check the dish of the wheel? That's more or less the point of my question, if you catch my drift. What should a properly dished wheel look like? What sign would there be your wheel wasn't dished properly that you could feel just by riding the bike?
What does dishing do, and how much should I know about it in order to keep my bike in good shape if I'm just an average rider?
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#9
JanJ, your reply is exactly why I asked this question. I don't know how many times I've gone to adjust one little thing on my bike and wound up with hours and hours of trying to get everything back together properly because one thing led to another and I ended up over my head. Fixing a bike can be fun, but it's easy to make things worse, as you mentioned.
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#10
I can say with confidence that some of the blame on the things that went wrong - belongs to me...
I'm just thankful that the knowledge was available, and patience was used in my 'education' Smile!

As far as I can tell, both bikes have ended up being far better because of the work expended on them.... I'm looking forward to riding them next spring!
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