Bicycle Mechanics - Dishing tolerance.

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View Full Version : Dishing tolerance.


bjkeen
04-30-06, 05:09 PM
When you're building a wheel, what's an acceptable tolerance for the overall dish?

Reason I'm asking is that I built up a Nexus 8 wheel as my first ever. There a millimeter or less of runout horizontally and vertically in the rim, but I come to find after I mount the rim in the frame (which is fine, in alignment, etc) with the tire on it that it seems to be offset about a mm or two to the left. There was a little more but I put in a washer (the dropout on the bike I'm using is 132.5; the O.L.D. of the hub is closer to 130 anyway) and improved it to about 1mm or so now.

I built it with a truing stand that purports to be 'self centering' so that no dish stick is required, but apparently I made a mistake.

Now, there's nothing ugly about spoke tension on either side of the wheel and I'm using a hub brake so there's not even any hint of a braking problem. It seems to feel just fine when I ride, too.

So, basically, we're talking something barely visible to the naked eye here, small in scale compared with the footprint of tire on pavement, and my main question is 'do I need to fix it right away because boy in such and such a riding situation I sure will notice it' or 'your wheel will EXPLODE!' or 'chill out; if it's still bugging you two years from now fix it the next time you change the tire.'


Al1943
04-30-06, 06:30 PM
It's pretty easy to correct the dish, simply adjust the spokes. I check the dish by reversing the wheel on the truing stand several times during a build. The TS-2 truing stand, like I use, is one that is purported to be self centering but in reality is not.

Al

bjkeen
04-30-06, 07:38 PM
I know how to correct the dish. I just built a wheel, geez. My question is whether a millimeter or two of error is going to make a difference.

Example:
My chainline is off by a millimeter. (no big deal)
My seatpost diameter is off by a millimeter (big deal)


dbg
04-30-06, 07:50 PM
A mm won't make any difference. And to check your "self centering" trueing stand just flip the "trued" wheel over the other way and see if it's still true. My Minoura WorkmanPro "self centering" stand is off (to the left) by about 1.5 mm.

BTW, my spoke-calculator shows that hub needing almost identical spokes on both sides. I've built up 5 Nexus-7 hubs with no dish (perfectly symetrical) and they are just fine.

bjkeen
04-30-06, 07:54 PM
Yeah, the spokes I used were only a mm or so different left flange vs right flange (I built the wheel 4-cross), and amazingly enough, I've got that 'self centering' Minoura stand as well. It's good to know that it's a little whacked out that way. And consistent in the 1.5mm to the left, wild. I kept checking it with that little triangle thing too.

Otherwise I like it well enough, where 'well enough' means that it was cheap and better than doing the wheel on the bicycle itself.