Dishing a wheel

[Cycleops]

I’m currently involved restoring an old Trek 1000 SL which I found down here much the worse for wear. Everything is there except the back wheel. I bought a ‘Home used’ one as they call it ( means it was brought into the country used) with a free hub appropriate for eight speed as original. The trouble is the rim doesn’t run central in the frame. My cycle repair guy says no prob just put spacers to shift it over, which we did but this makes the axle too wide and it’s a barsteward to get in now.
I thought you can dish the wheel by loosening the spokes one side and tightening them on the other but he say no. I thought this possible but is it?

 

[AndyRM]

@JhnBssll or @Gunk may be able to help you out?

 

[Vantage]

Your cycle guy doesn't know his stuff.
Loosening on one side and tightening on the other is exactly how wheels are dished.

 

[JhnBssll]

As above, thats exactly how you do it. Whether or not its possible on an old wheel is another matter, it would only take one seized nipple to cause you a headache. Certainly worth a try though! I'd probably start at the valve hole and try to loosen every nipple by half a turn first to gauge the state of play. If successful I would go back around and retighten the spokes on one side to begin pulling it over. Always work out from the valve hole and only ever tweak the nipples a bit at a time, dont go getting cocky or you'll end up with a pringle

 

[C R]

Your cycle guy doesn't know his stuff.
Loosening on one side and tightening on the other is exactly how wheels are dished.

But doesn't that require the length of the spokes on each side to be right for the right amount of dish needed? If the spokes are not the right length there may not be enough adjustment available.

 

[JhnBssll]

But doesn't that require the length of the spokes on each side to be right for the right amount of dish needed? If the spokes are not the right length there may not be enough adjustment available.

The spoke lengths will likely be close enough to allow a few mm of dishing in either direction. If its needs shifting 10mm you may start to encounter problems, but its a good point

 

[Vantage]

But doesn't that require the length of the spokes on each side to be right for the right amount of dish needed? If the spokes are not the right length there may not be enough adjustment available.

Some builders advise that the drive side spokes should be a a smidgin shorter than the non drive side but I think that only applies if the builder is particularly anal.

 

[swee'pea99]

It's easy. Seriously. Just don't get distracted or lose your place! Start by checking to see if the spoke nipples will turn easily - just tweak three or four slightly to check. If you have any problems, a little oil and leave a few minutes. Then it's just a question of going round the wheel tightening a spoke, loosening the next, tightening the next, loosening the next, and so on - try just half a turn for each for starters. When you've got right round the wheel, see if you've shifted the rim far enough. If not, go round again doing the same thing. As long as you don't get muddled, you shouldn't have any problems. First time I did it I was really doubtful, but it turned out to be really easy, and I was done in less than half an hour.

 

[rogerzilla]

Some builders advise that the drive side spokes should be a a smidgin shorter than the non drive side but I think that only applies if the builder is particularly anal.

2mm is the usual difference, but since you don't have to buy spokes in packs of 36 or 72, you just buy the closest to what the spoke calculator recommends for each side.

 

[JhnBssll]

A lot of hub manufacturers will make the driveside flange slightly larger diameter than the non-drive side - this requires a slightly longer spoke, and offsets the effect of dishing allowing the same length spokes to be used on both sides. It seems counter intuitive that reducing the gap between the rim and flange needs a longer spoke, and it's only true for cross-laced wheels.

 

[Cycleops]

Thanks for the help guys. I gave it a go and it’s sitting right in the middle of the dropouts 👍.

 

[Venod]

A lot of hub manufacturers will make the driveside flange slightly larger diameter than the non-drive side - this requires a slightly longer spoke, and offsets the effect of dishing allowing the same length spokes to be used on both sides. It seems counter intuitive that reducing the gap between the rim and flange needs a longer spoke, and it's only true for cross-laced wheels.

If the wheels are built with the same spoke cross pattern on both sides, increasing the flange diameter will result in needing shorter spokes at that side.

 

[Ajax Bay]

increasing the [drive side] flange diameter will result in needing [even] shorter spokes at that side.

Agree and edited/FTFY. @JhnBssll probably mis-spoke and meant to say "will make the non-drive side flange slightly larger diameter than the drive side" A larger RH flange also slightly improves (increases) the spoke angle.

 

[JhnBssll]

Sorry guys, I wasn't quite right for all wheels, but it's not as simple as you'd think. For the last few wheelsets I've built I stand by my statement - larger driveside flange = longer driveside spoke. These have been 24 spoke 2-cross builds and due to the angle at which the spoke meets the hub if you make the flange wider the spoke gets longer. I did a couple of calcs to prove it, first with 60mm flanges on both sides of my imaginary rear wheel...

You see the driveside spoke is slightly shorter than the non-drive side, as you'd expect due to dishing. Then increasing the drive side flange diameter slightly to 65mm - the drive side spoke has grown to match the other...

Due to the angles needed for this to be true if you go to 28 or more spokes they get shorter again as you increase the flange dimensions. Interesting little phenomenon though, and it explains why you generally only see asymmetric flanges on lower spoke count hubs.

Obviously if you lace radially and increase the flange they get shorter no-matter how many spokes you have

 

[JhnBssll]

I just knocked this image up to explain it. Using a standard 24 spoke wheel:

If you look closely at the point where the spoke meets the hub, it's quite a long way around, almost 90 degrees, shown below by the red line.

The spoke I've coloured green is the original length spoke and the blue spoke is one I've drawn in to meet an imaginary larger diameter flange. It's clear in this case that the blue spoke will be longer than the green spoke. In fact in any case where the angle between the red line and the spoke is greater than 90degrees a larger flange will give a longer spoke