Wheel Dishing Dilemma

[Stradageek]

P.S. Does any one check wheel alignment after putting wheels back in after rebuild?
Like a straight edge down both sides of rear wheel to see it lines up with front wheel.
If it does not then the bike will handle like a whale.

Mike Burrows (he of the monoblade obsession) might take issue on this.

He built a series of bikes with greater and greater offsets and has said that it had to be a 60mm offset before he noticed anything different. He adds that he got used to the slightly odd feel (of a 60mm offset) after only 10mins cycling and thereafter never noticed it, though he did add that getting both wheels to avoid potholes was a bit trickier

[jb]

P.S. Does any one check wheel alignment after putting wheels back in after rebuild?
Like a straight edge down both sides of rear wheel to see it lines up with front wheel.
If it does not then the bike will handle like a whale.

Mike Burrows (he of the monoblade obsession) might take issue on this.

He built a series of bikes with greater and greater offsets and has said that it had to be a 60mm offset before he noticed anything different. He adds that he got used to the slightly odd feel (of a 60mm offset) after only 10mins cycling and thereafter never noticed it, though he did add that getting both wheels to avoid potholes was a bit trickier

I think its more angular misalignment that makes it handle badly (or crab as they say)

[Stradageek]

My bad, or rather my misinterpretation - angular misalignment would be an issue though difficult to get wrong on a bike with vertical dropouts

[Manc33]

...he did add that getting both wheels to avoid potholes was a bit trickier

Everywhere talking about dishing wheels says:

"On wheels with cassettes and freehubs, the NDS spokes are at a lower tension than the DS spokes, to keep the rim central".

OK I get that, but if it were physically possible to have a cassette on with the spokes at roughly the same tension, that would be better, right?

I mean having even tension is the original aim and having a cassette is interfering with that.

You can't put spacers on a quick release wheel because only about 5mm of the axle is sat in the dropout and even when you have a full axle, you're limited (as to how many spacers you can have) by the length of the axle and how much the dropouts can be bent apart - but IMO this is the better way to get the rim central, if it can be done that way, simply because it means the NDS spokes can be a bit tighter.

I read NDS spokes should be at least 60 kgf and DS spokes at least 110 kgf. That's 83% more tension on the drive side. Those add up to 170.

My wheel has ended up averaging out to 76 kgf on the NDS and 91 on the DS. That puts the DS spokes at only 20% tighter. Those add up to 167.

[jb]

The tension on the NDS is a function of the DS so the ratio can only be altered with the amount of dish. The only way round this is to have an asymmetrical frame built with offset rear dropouts. Then of course your small sprocket is miles away from alignment with the big ring.

[Manc33]

Cheers jb, that is at least one thing that's not getting altered about my setup, as I add spacers to the NDS, the cassette lockring has remained as close to the dropout as it can get (allowing for a chain on the last sprocket).

[NATURAL ANKLING]

Hi,
If the non-DRIVE side flange is sharing half of the total hub torque, Then yes a central rim position is preferred.

It's a pity that our residential expert is not participating at the moment.

[531colin]

On a regular 135mm OLN 8, 9, 10 speed wheel I get 120kgf driveside and 80kgf NDS. (ie average tension 100kgf) With even tensions and good stress-relief you won't get any problems.
If your rim won't take 120kgf, both sides will have to be at a lower tension, and threadlocking the NDS nipples can become necessary.

Reading backwards on this, with a very large flange hub if you reduce the number of crossings then you get a better angle between the spokes and the rim....if your spokes curve where they enter the nipple its best to give them a permanent bend; exactly the same as if they curve at the hub...this is to avoid fatigue when the spokes flex each revolution. I think Thorn now lace Rohloff hubs 1 cross, but check that.
2.5mm thick spokes sound like 13 gauge. If they work then all well and good, but if you have to do a complete rebuild then I would go for thinner spokes of a known brand (as you say). Big hubs and fewer crossings mean shorter spokes which means there is less stretch in the spokes, so for a spoke to go completely slack takes less rim distortion....so I would go for butted spokes which stretch more for a given tension..... but there are other opinions.

[Manc33]

I'm dishing a wheel again (with Park Tool WAG-5) but there's the usual problem that seems to happen every time...

Spokes that aren't tight enough as it is (on the non-drive side) need to be loosened to send the rim the right way.
- and/or
Spokes that are getting too tight as it is (on the drive side) need to be tightened to send the rim the right way.



Doing either of the above will fix the dish, but doing either is wrong. The only "solution" could be to deliberately dish the wheel slightly off center? I don't know how else it can be fixed. Help! Isn't it more important to have spokes tensioned properly than it is to have your wheel exactly central?

[531colin]

Is it individual spokes which are too tight or too loose?
If its individual spokes, you have to "share out" the tension between adjacent spokes from the same hub flange.....so if you have a "too tight" spoke, share its excess tension between its adjacent spokes from the same flange. Oddly enough, this is a problem with big strong rims and thick spokes....with a light rim and thin stretchy spokes you get an elastic structure which shares out the tension all on its own......in itself, this doesn't always make them easy to build!
If its all the spokes driveside are too tight (for example) it looks like you are trying to do something which isn't going to work.

[Manc33]

531colin thanks for pointing that out. Yes there are a few problem areas where there's a loose spoke with two tighter ones either side of it. There's 3 spokes on the NDS that show on my tension tool as: 26.0 / 20.5 / 26.1

So I can get those 3 evened out I guess. I totally forgot I had bought a tension tool and just dug it out.

According to that tool, a reading of 23 means 96 kgf and a reading of 24 means 107 kgf, so something like 23.4 on the tool is about 100 kgf, which I am aiming at.

NDS Average: 24.73 (about 117 kgf)
DS Average: 22.53 (about 90 kgf)



On the dishing tool, there's no gap on the NDS and about a 4mm gap on the DS. That means either the NDS needs tightening (already averaging 117 kgf) or the DS needs loosening (only averaging 90 kgf).

I might as well just leave it 2mm off center or, even more because I don't fancy it staying at 117 kgf on the NDS!

EDIT: Oh maybe 117 kgf isn't so bad after doing more reading.

[531colin]

If this is a normal cassette wheel, I think you have the terminology the wrong way round? Driveside should be tighter?

If the rim is reasonably straight, you should be able to get all the spokes on one side to the target number plus/minus one (thats 1.0, not 0.1)

So where you have (I'm rounding to whole numbers) 26, 26, 21, 26, 26 I would take 1/2 turn off all the 26 spokes and give 2 turns to the 21 spoke, and then re-measure. Thats the worst-matched group, so I would start there, and eventually aim at getting them all plus/minus one (on the same side, obviously)

i find it much better to use the tension gauge throughout the build, rather than fishing it out at the end and finding you have more work to do than you thought!

I reckon to build a 135mm 8,9,10 speed wheel 120kgf driveside, 80 NDS

2mm off-centre won't notice, but if you are building for customers they can get very shirty over the odd millimetre!

[Manc33]

Sorry I never said, it's a front wheel, but a disc hub so there is a mild dish to it. At least the NDS being tighter on it (the disc side) is to be expected.

It's the wheel I'm putting that Tannus solid tyre on so I just want to make sure it's not got loose spokes, it's a 36h rim for that reason. It seems quite unusual to find a front wheel with 36h these days! I'd have 40h if I could but then it wouldn't be a bog standard Shimano hub which is what I'd rather it had. If it's a factory built wheel then it's been made almost spot on, didn't need really any truing and all the spokes were already there or thereabouts.

[531colin]

If the front tyre contact patch isn't directly in line with the head tube, the steering will be a bit "off", so I always start with the front wheel perfectly centered.....I have been known to file the dropouts to get it spot on.
I can't remember what front disc wheel tension comes out at, but you want 100kgf average so maybe 110 disc side 90 non-disc? Theres less dish than a 135mm 8,9,10 speed rear anyway!

001 by 531colin, on Flickr

002 by 531colin, on Flickr

[Manc33]

With it adjusted so the dish is central the DS spokes are only averaging about 65 kgf (lowest about 55 kgf).