Author Topic: Why isn’t my wheel centred?  (Read 1494 times)

AlexRa

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Why isn’t my wheel centred?
« on: July 28, 2024, 08:28:49 PM »
I’m building my hub into a new wheel. The wheel appears to be centred between the hub flanges. But the wheel appears not to be centred between the drop outs. I feel like I’m missing something really silly here! What’s going on?

See photos on this post:
https://www.reddit.com/r/Rohloff/s/H4nE5hUnaQ

PH

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Re: Why isn’t my wheel centred?
« Reply #1 on: July 28, 2024, 08:57:07 PM »
I don't class myself as an expert wheel builder, I've built a grand total of five, two of which are Rohloff.
It's a symmetrical build, so assuming all spokes are the same length and that you're using Rohloff spokes, here's what I'd do:

Have a cup or tea
Slacken all spokes til one thread is showing
Give all the spokes a squeeze so they're seated OK
Double check the lacing pattern
Have wheel nuts on all the time the wheel is in the stand, fairly tight
Measure it at this point (67.5mm less half the width of the rim) it'll be baggy, but it ought to already be symmetrical. If the spoke length is correct, it should hold it's shape at this point.  If not give every nipple a full turn.
IF NOT SYMETRICAL NOW
Triple check the lacing pattern
Don't trust that the stand is symmetrical - take a measurement on one side of the rim, turn the wheel around measure from the same side of the stand.  If in doubt, stick the wheel in the bike.
Keep doing this till the baggy wheel is symmetrical
ONLY WHEN IT IS
Start tensioning one turn at a time in full rotations of the wheel.
Don't bother checking anything again till it's feeling pretty tight

I've never measured if a rim is central over the hub, it's a given.  When I've done the above, there's very little final tensioning and adjustment to do at the end. 
Before you're done, proper stress relieve them, several different ways and plenty on youtube demos, failing to do this properly is IMO the biggest cause of wheel failure.

EDIT - it might just be the photos, but in the third one it looks like the lug on the plate is sat on the leg of the stand.  If the axle isn't sat square in the stand, the wheel is never going to be true.

EDIT EDIT - Not what you asked, but I'd be doing two things differently, I'd be adding flange support rings and while I was waiting for those I'd polish the hub, it isn't anodised so half an hour's effort with a proper polish will have it looking like new.  And it's a lot easier to do it out of the wheel.
« Last Edit: July 28, 2024, 09:44:55 PM by PH »

mickeg

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Re: Why isn’t my wheel centred?
« Reply #2 on: July 29, 2024, 12:05:02 AM »
I do not have a truing stand, I just use the frame or fork as my truing stand.

To avoid having a wheel with a rim that is offset to one side or the other, I frequently take the wheel out of the frame or fork and turn it around and put it in the other way.  Do that repeatedly.

If the rim is offset to one side, when I turn it around, if it really is offset to one side it will then be offset to the other side, which is most obvious.  That tells me which side needs tightening more. 

Since I do that before all the spokes are fully tight, I rarely have to loosen any but if you have brought the wheel to full tension, then of course some spokes need to be loosened before you can tighten the other side.

Are you aware that Rohloff suggests you add the flange reinforcing rings when you rebuild a wheel?
https://www.rohloff.de/en/company/news/news/flange-support-rings


martinf

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Re: Why isn’t my wheel centred?
« Reply #3 on: July 29, 2024, 07:27:51 AM »
Both PH and mickeg have already covered this.

It is possible to buy a dishing tool :

https://www.parktool.com/en-us/blog/repair-help/wheel-dishing-centering

But I don't understand why this would be needed. When you have a trueing stand it is easy enough to turn the wheel several times until the rim is symmetrical in the stand.

I've built quite lot of wheels. I never bother about whether the rim is symmetrical between the hub flanges. For rear wheels in most cases it isn't.

Rohloff may be an exception (I've only built one Rohloff wheel and didn't check), and with other hub gears and single speeds there is generally much less wheel dish than with a derailleur wheel.

_______________________________________________________

Unlikely that you have one of the following two cases:

- there are a few frames where the rear triangle isn't symmetrical, the idea being to reduce dish with a derailleur wheel. So if you have one of these it is easier to start the wheelbuilding with the wheel in the bike and just use the stand to finish tensioning and trueing. I've had a bike where I had to build the wheel with about 5 mm of rim offset, but I think that particular frame had just been cold set for a wider hub some time before I got it rather than being designed that way.

- and at least one make of bike (Brompton) where you should build the wheel with the rim symmetrical in the stand, but where the rim is closer to one "chainstay" when fitted to the bike. The bike is designed like that, perhaps because of the fold.

PH

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Re: Why isn’t my wheel centred?
« Reply #4 on: July 29, 2024, 09:47:23 AM »
Looking at the photos again, and it might just be the photos, there appears to be a lacing error.  In the third photo the spoke pair left of centre appear to cross a lot closer to the hub than the other pairs. The rim opposite that also looks odd.

PH

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Re: Why isn’t my wheel centred?
« Reply #5 on: August 06, 2024, 03:52:21 PM »
So how's it going?  Is it sorted?  Interested to know what the issue was.