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· Frog Whisperer
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Discussion Starter · #1 ·
I have a question about truing, and dishing wheels. I have a friend who is a machinist and he mounted a dial indicator on his truing stand….I borrowed it and I want to tell you, you can get the wheel to within a .001 of an inch of true with a little work, probably way truer than a wheel needs to be. The next logical step was to take an old wheel and loosen all the spokes and try it from the beginning. The it occurred to me that I would need to dish it properly. SO……if I remember correctly, the rear dropout width is 130 mm so…if I took the 130, divided by 2, measured the width of the rim, divided that by 2 and added the two together (for example if the rim was 30 mm add 15 to 65 = 80) and set the dial indicator to that measurement and zeroed it out, then shouldn’t the wheel hypothetically be perfectly true and perfectly dished? Or an I missing something?
 

· Adorable Furry Hombre
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32,358 Posts
Touch0Gray said:
I have a question about truing, and dishing wheels. I have a friend who is a machinist and he mounted a dial indicator on his truing stand….I borrowed it and I want to tell you, you can get the wheel to within a .001 of an inch of true with a little work, probably way truer than a wheel needs to be. The next logical step was to take an old wheel and loosen all the spokes and try it from the beginning. The it occurred to me that I would need to dish it properly. SO……if I remember correctly, the rear dropout width is 130 mm so…if I took the 130, divided by 2, measured the width of the rim, divided that by 2 and added the two together (for example if the rim was 30 mm add 15 to 65 = 80) and set the dial indicator to that measurement and zeroed it out, then shouldn’t the wheel hypothetically be perfectly true and perfectly dished? Or an I missing something?
It should become fairly obviouswhen you set about it with a gauge...but... make sure you double check the axle width-depending on how 'old' old is, it could be a 126.
 

· Registered
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619 Posts
ericm979 said:
Subtract 1/2 the rim width, not add. The difficulty is getting the indicator to zero on the plane of the outer face of the locknut. If you can do that it'll work.
It's a lot easier to set the dish with a dish stick or a table. Dials are designed to measure small differences, not locations, and unless you have a pro grade truing stand, you will never find an accurate reference.
FWIW, Racelite wheels are trued to 15/1000, and even that is truer than typical tires.

em
 

· NeoRetroGrouch
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6,493 Posts
Touch0Gray said:
I have a question about truing, and dishing wheels. I have a friend who is a machinist and he mounted a dial indicator on his truing stand….I borrowed it and I want to tell you, you can get the wheel to within a .001 of an inch of true with a little work, probably way truer than a wheel needs to be. The next logical step was to take an old wheel and loosen all the spokes and try it from the beginning. The it occurred to me that I would need to dish it properly. SO……if I remember correctly, the rear dropout width is 130 mm so…if I took the 130, divided by 2, measured the width of the rim, divided that by 2 and added the two together (for example if the rim was 30 mm add 15 to 65 = 80) and set the dial indicator to that measurement and zeroed it out, then shouldn’t the wheel hypothetically be perfectly true and perfectly dished? Or an I missing something?
How do you know (how do you set the dial indicator) to the width of the outer lock nut? How is it mounted that you can find this point?

I believe (though I cannot visualize your set up) that it would be eadier to simply turn the wheel around and get the same measurement both ways.

TF
 

· Frog Whisperer
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41,516 Posts
Discussion Starter · #6 ·
dohhhhhhhh..

ericm979 said:
Subtract 1/2 the rim width, not add. The difficulty is getting the indicator to zero on the plane of the outer face of the locknut. If you can do that it'll work.

ok...I see that, sorry....a mathemetician I aint....
My friend says he has "gauge blocks" that would do it? or a parallel thing? he says it wouldn't be hard. And he says to measure using the calipers and not assume 130 or any other number. I mean I am not going into the wheel building business, but I just want to see if I can do it. ('specially since the wheel I am experimenting with has bad bearings and races, but I am not messing with my good wheels except to true them....and they are REAL true.)
 

· Registered
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1,876 Posts
Touch0Gray said:
I have a question about truing, and dishing wheels. I have a friend who is a machinist and he mounted a dial indicator on his truing stand….I borrowed it and I want to tell you, you can get the wheel to within a .001 of an inch of true with a little work, probably way truer than a wheel needs to be.
Laterally or radially? Lateral true is the easy part. How true can you get it radially?

Al
 

· Frog Whisperer
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41,516 Posts
Discussion Starter · #9 · (Edited)
pretty good...

Al1943 said:
Laterally or radially? Lateral true is the easy part. How true can you get it radially?

Al

that was harder ...you get it perfectly round and when you true it laterally it throws that off...so you make it round and it throws the lateral off again....I spent a LONG time ....but I am about .006....which is so critical when you are riding down a road which is nothing but a string of 3 to 5 inch potholes, strung together by the "tailings" from the holes!........oh my aching kidneys
 

· Larry Lackapants
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698 Posts
I guess none of you guys can complain that his frame is not "true" - fork and rear dropouts are not very good aligned on my (aluminum) frame, so truing the wheels ON the frame and using the brake pads as reference regarding vertical/lateral trueness, is most helpful

Good luck
br
 
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