First Wheel Building Experience

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robwa10
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Postby robwa10 » 19 Dec 2008, 12:23pm

Mick F wrote:(I envy you, I'll have to buy some bits and make some new wheels just for the hell of it!!)


Mick it's become like cocaine to you, you're addicted!!

Quick, get Mrs F to change your pin number and barricade the money box. They'll be nothing left after the parts for the wheels and that Rohloff hub! :wink:

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robwa10
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Postby robwa10 » 19 Dec 2008, 12:53pm

Thought some of the comments from an earlier thread on wheel building might be beneficial so I've copied them into this one.

Dean
Mick F wrote:
Rigida Chrina rims in anodised silver, 32h front and 36h rear.
Campagnolo Chorus hubs.
ACI Stainless Double Butted spokes but with Plain Gauge on the drive-side rear.
All shiny and new!

since you bring it up...

I've seen this mentioned a few times - what's the advantage?


Mick F
Good question.

Stronger spokes on the drive side are required as they are under a great deal more tension than the non-drive side. This is because of the severe 'dish' of a road wheel - especially with a Campag hub.

The drive-side hub flange is not far from the centre-line of the wheel, making the spokes appear almost vertical.

I haven't seen the maths behind it, but a spoke that is thinner must be stretchier and weaker than a thicker one.

Look at the links to Spa and read the descriptions:
http://www.spacycles.co.uk/products.php ... b0s156p494 Plain Gauge - Ideal for drive sides for lighter wheelsets.
http://www.spacycles.co.uk/products.php ... b0s156p533 Double Butted - Ideal for front wheels and non drive sides of wheels.
The DB spokes are 2mm thick at each end, but only 1.7mm thick for the majority of their length. The Plain spokes are 2mm throughout.

Please don't think I'm any great expert, I'm very much in the learning stage. I'm good with my hands and enjoy tinkering and learning new skills. I started out by pulling apart a old set of wheels and re-building a couple of times until I got the hang of it. All you really need is a good spoke key and your bike frame as a jig.

Oh, and a good eye!
_________________
Mick F. Cornwall


pigman
interesting re the plain gauge spokes on one side, but I cant see the point of having the excess meat in the centre of the spoke. My experience of breakages has been at the hub end, where DB or not, there is 14gauge metal. (im not disagreeing, just dont understand)
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Mick F
Spambuster

Maybe someone more experienced could enlighten us!

I know that the thicker the spoke, the stronger the wheel. Also, the higher the spoke count, the stronger the wheel.

As for breakages at the hook-end, I agree that that is where they usually break. I understand that you can buy spokes with very thick hooks.

What causes a spoke to break?
_________________
Mick F. Cornwall


Dean
I was of the understanding that double-butted spokes are stronger than plain gauge, since the thinner middle section allows them to compress and spring back into shape more easily.

I'm relatively new to wheelbuilding too, so I don't pretend to be an expert. And until recently I've built exclusively front wheels or fixed wheels, which require zero dishing - hence my asking the question.


rogerzilla
I always use d/b on both sides, and have never broken (or even loosened) a spoke, except in a major prang.

Plain gauge spokes have no advantages except cheapness. There are, however, single-butted spokes which may have an advantage on the drive side, because they have a thicker elbow (the same as the major diameter of the thread, which is about 2.3 mm and only just fits through the hub spoke hole), which is where you need the extra metal.


Mick F
We await an expert!
_________________
Mick F. Cornwall


Dean
My distinctly unprofessional approach to wheelbuilding:

Buy hubs and rims. *This is important*: Measure them carefully. Correct measurement determines the spoke length, which I have found to be the most critical factor in wheelbuilding. Using the wrong length of spokes is frustrating at best.

Lace the wheels (Sheldon Brown's site, as linked to in MickF's OP, is excellent).

Use the frame and forks as truing jigs. Blu-tack and a bit of old spoke can be used for lateral truing (making sure it runs straight), as the spoke makes a "Ping" when it catches the rim. Or you can use the brake blocks.

For roundness, you can put a tie-wrap around the frame/forks. This helps you gauge the height of the rim at any given point.

For dishing (making sure the wheel sits centrally), the cheapest way is to flip the wheel over.

Unless you're building wheels professionally, as in daily and for a living - I don't think you *really* need a truing jig or a dishing tool - all you need is the frame and a spoke key (make sure that it fits the nipples correctly).

As well as Sheldon's site, I found the Park Tools website useful on building wheels. Just ignore the bits where it says you need a truing jig, spoke tensioner etc:

Park Tools US

Roger Musson's website allows you to download his book on wheelbuilding ( I haven't yet, but I am assured that it is excellent). and it also has a free-to-use spoke calculator, and a good description of how to measure hubs and rims:

http://www.wheelpro.co.uk/spokecalc/

Is it cheaper overall? I'd say it probably is, but mostly it's more satisfying to build my own, and I'm not relying on some spotty yoof in a bike shop nwhom I wouldn't trust to hold a spanner correctly (having been that spotty yoof, I know whereof I speak).

DIY. It's usually the best way to go.


Mick F
Great!

When I made up my new ones, I laced up the front first in the manner I described.

I then started tightening a little at a time, and lo and behold, the wheel was perfect without using my frame or jig! Just sat on the settee holding the wheel and it was fine. I tensioned it in the jig later, but it was almost there!

I bet you're going to ask about spoke tension next. Not my strong subject, I worry about it a little. All I do is make sure the spokes "feel" right. Also, the nipples start to creak as you tighten them and get difficult to turn and I worry that I'm going to strip something. That's when I think it's right. I use my mechanical aptitude to know when if feels right.
_________________
Mick F. Cornwall


lauriematt
not too worried about spoke tension.....generally you ' feel ' what the limits are

i made the mistake ( & im sure im not the only one ) when lacing the wheel - i had the correct spoke pattern but the spokes werent laced right. i tightened it up and was wondering why the spokes werent touching each other. then i realised that the spokes werent laced over each other!
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NO PAIN - NO GAIN!!!!!


PW
Tension the spokes until they feel right, then stress relieve the wheel by taking hold of parallel pairs of spokes and giving them a good squeeze in the centre - you'll need gardening gloves or it rips your palms to bits. Do each pair starting with the two pairs which bridge the valve hole. If the wheel stays true, tension it another 1/4 turn all round and repeat. Eventually it will go out of true in 4 smooth waves. Back off every spoke 1/4 turn, true it up and it's finished.
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If at first you don't succeed - cheat!!


axel_knutt
Mick F wrote:
Great!

I bet you're going to ask about spoke tension next. Not my strong subject, I worry about it a little.

I'm not sure it's anyones strong subject!

When I did my first wheel this was the one point I was unsure of, so I emailed Sheldon Brown, DT Swiss, and CJ. None of them gave a particularly straight answer so I set mine at 1kN (a mean of 1kN on the rear), which is the tension Brandt refers to as "typical". I've had no problems.


pigman
I've never been one for scientifically tightening up things with torque wrenches etc, so wouldnt know how to measure it in any definitive unit. easiest way is to check a wheel you know is good and squeeze adjacent spokes (not adjacent at the hub or rim, but in the middle where they cross) to get a gut feel. Then copy on your wheel and jobs a good 'un. as you get experienced wheelbuilding ,you wont need to copy, youll have that intuitive experience. Never failed me yet.
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CJ
Moderator
rogerzilla wrote:
I always use d/b on both sides, and have never broken (or even loosened) a spoke, except in a major prang.

Plain gauge spokes have no advantages except cheapness. There are, however, single-butted spokes which may have an advantage on the drive side, because they have a thicker elbow (the same as the major diameter of the thread, which is about 2.3 mm and only just fits through the hub spoke hole), which is where you need the extra metal.


Mick F wrote:
We await an expert!

I don't like to call myself an expert (ex: a has-been, spurt: a drip under pressure!) but here goes.

Spokes slacken when the bit of rim they're attached to gets pushed upwards by the road/tyre. They have to be tight enough that they hardly ever go completely slack (only when you hit a really big bump!) but not too tight, since either going slack or higher average tension will both shorten the fatigue life of a spoke.

The trouble with dished wheels is one side must be much tighter than the other. So if you use the same spokes both sides, none can be at their optimum tension. A compromise is required, which in the case of the common rear cycle wheel means the left side spokes are not really tight enough, so that one goes completely slack from time to time (frequency depending on the weight carried, stiffness of rim, bumpiness of road etc.) whilst the right side is tighter than optimum.

With modern road wheels demanding twice the left spoke tension on the right, this compromise is not insignificant.

Regardless of how far one may have ridden such a wheel without breaking a spoke, one could have ridden it further (or ridden a lighter one in the first place) if it were specified with spokes that are designed to take a higher tension in the side that necessarily has a higher tension, and vice versa.

Single-butted spokes (and others with an extra thick head section, sometimes called triple-butted) are designed to withstand a higher build tension, all other factors being equal. So they are what you really want in the right side, IMHO. In the case of a lightweight wheel I'd choose the DT Alpine-3 (so-called triple butted, but really double butted) that have a thinner 1.8mm centre section between the 2.3mm head and standard 2.0mm thread.

Meanwhile on the left you want double-butted with a much thinner centre section. Reason for that is to ensure that the spoke stretches by about the same amount as the right side spokes, in the process of tightening them to a necessarily lower tension than the right side spokes. That way, when the wheel deflects, spokes on both sides of the wheel relax in unison. An additional benefit of such "elongation matching", is that the rim does not also pull to one side as it deflects upward, so it's less likely to buckle when you hit a bump.

Whilst an entirely plain gauge wheel is less durable than an entirely double-butted, the same does not apply to the judicious combination of double-butted and plain in a dished wheel. Although the plain gauge do not have the extra-strong heads of single-butted, their greater stiffness compared to double-butted still provides all the symmetry benefits of elongation matching.

So whilst Mick might well have spent a bit more on even swankier spokes, that could have given a marginally even finer rear wheel, the combination of double-butted left and plain gauge right brings a lot of the same advantages.
_________________
Chris Juden


CJ
Lawrie9 wrote:
Clear as mud!

Attempt at simple version:

In a typical road bike rear wheel the rim is half as far from the right hub flange than the left, and right spokes have to be twice as tight as the left spokes to pull it off-centre like that.

Or else there could be twice as many spokes on the right, as in a Campag G3 wheel, and as in all similarly dished spoked wheels on motorcars. Motor engineering apparently does not tolerate foolish design, cycling on the other hand ... but I digress.

Bike wheels are mostly condemned to have the same number of spokes both sides, even when they're dished. The response of an intelligent designer to this constraint is to use spokes that are twice as stiff on the right.

Think about what happens if all the spokes are the same stiffness and the right side ones are twice as tight to start with. As the rim is pushed up towards the hub the left spokes go completely slack first, whilst the right ones are still pulling, so the rim shifts to the right, as far as the sideways bending stiffness of the rim may allow. Push the rim hard enough and the lateral and torsional strength of the rim will be exceeded. Result: the familiar buckled wheel.

If the right side spokes are twice as stiff as the left however, the inbuilt 2 to 1, right to left tension ratio is maintained during any local reduction in spoke tension, as the rim is pushed upwards toward the hub. Rim deflection therefore remains purely radial in response to a radial load, with no inbuilt tendency to buckle one way or the other.

If the impact isn't truly square to the wheel of course, there's still some risk of it buckling. The simple wheel, admittedly, will be more resistant to leftward hits, but vulnerable to any knock that tends to push it to the right, since that's the way the radial load is sending it already.

Since there can be no consistent bias in the alignment of the edges of potholes etc.: the wheel built with tension balanced spoking, with equal resistance to random impacts from either direction, will be less likely to suffer damage.
_________________
Chris Juden


rogerzilla
Jobst Brandt uses the term "taco" to describe the shape taken by an overtensioned wheel when it deforms to try and get out of the way of the load (probably a form of Euler failure). "Pringle" is my favourite description.


CJ
Moderator
rogerzilla wrote:
Jobst Brandt uses the term "taco" to describe the shape taken by an overtensioned wheel when it deforms to try and get out of the way of the load (probably a form of Euler failure). "Pringle" is my favourite description.

Pringle, excellent, must try to remember to use that in future. Very Happy

But even a somewhat under-tensioned wheel will go that shape if you wallop the rim hard enough sideways.

An over-tensioned wheel however, will "pringle" all by itself, whilst you're over-tensioning it Embarassed

Or, if dished with same spokes both sides, a not-quite-so-badly-over-tensioned wheel will pringle by just riding along, i.e. a radial load.
_________________
Chris Juden


pigman
CJ wrote:
An over-tensioned wheel however, will "pringle" all by itself, whilst you're over-tensioning it

assuming that this hypothetically happens, would the rim be bent beyond repair (ie actually distorted), or would loosening "unpringle" it and leave it flat to try again?

I once saw, on a ctc invitation ride, a back wheel pringle whilst descending very carefully a 1-in-5/1-in-6 hairpin. Bike was very old & unmaintained all round and judging by the front wheel which was still intact, I'd say it was undertensioning, rather than overtensioning that caused it.

BTW what an invitation ride that was. Twas the most hilly area round Bradfield/strines/langsett - not exactly easy or endearing to joe public.
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CJ
pigman wrote:
CJ wrote:
An over-tensioned wheel however, will "pringle" all by itself, whilst you're over-tensioning it

assuming that this hypothetically happens, would the rim be bent beyond repair (ie actually distorted), or would loosening "unpringle" it and leave it flat to try again?

Didn't you notice my Embarassed ? There's nothing hypothetical about it, I assure you!

Fortunately it started slow, and I knew enough to realise exactly what was going on when my attempts to true whilst tensioning only made the deviations bigger. So the rim hadn't gone beyond its elastic limit and backing off the tension all round restored it to roundness. Starting from a zero tension, true wheel, subsequent tensioning to a lower "note", was successful - at least until the bike got stolen!

My excuse for over-tensioning is I was using an old-stock open-section rim to build a college hack bike for my son. All the other wheels I'd recently built had torsionally much stiffer box section rims, which can stand more tension (and bigger sideways hits) before "pringling" (what a versatile word this is!) so I'd become accustomed to tightening spokes that hard.

The relatively moderate tension at which this ocurred probably helped to make it a gradual and recoverable pringle. If it were to happen above the higher tension permitted by modern rims, the wheel would probably pringle more suddenly and would distort much further in order to relax the greater amount of spoke elongation, which increases in proportion to their tension. In that case it's very likely the rim would have yeilded and need to be overbent in the opposite direction to make it true.

Most people woudn't bother, but I have successfully straightened badly buckled rims using a flat surface and a collection of blocks of wood to press down and flatten the rim a section at a time. I've then gone on to build these restored rims into reliable wheels. It was less time and bother than trying to source something compatible with the existing number and length of spokes. Mick's rim however, is certainly beyond redemption!
_________________
Chris Juden


PW
"Tension by stress relieving" is Brandt's recommended method - as my earlier post. When the rim won't stand any more tension it "Pringles" when the spokes are tweaked, so you back everything off 1/4 turn, re-true it and the wheel is complete. They last for years when tensioned that way.
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If at first you don't succeed - cheat!!


pigman
CJ wrote:
Didn't you notice my Embarassed ? There's nothing hypothetical about it, I assure you!


sorry, no i wrote it badly. I wasnt inferring it couldnt really happen, I was thinking it wouldnt (or is it couldnt) happen to me - this sort of thing only happens to the overzealous/inexperienced tightener. But after reading that you had it happen to you, I guess I'm going to revise this view too. Anyway, thanks for the answer.
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Colin63
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Postby Colin63 » 19 Dec 2008, 2:15pm

Really inspiring. I've never built a wheel before, but I'm building up a collection of parts in the cellar and will have to have a go myself. Well done robwa10

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CJ
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Postby CJ » 19 Dec 2008, 3:09pm

Mick F wrote:I read loads of stuff, and typical of me, made my own mind up.

Me too!

I tried the ways of lacing a wheel given in books, but wasn't impressed by all the spoke-bending, ducking and weaving entailed towards the end of the process. So I invented myself a better way in which the spokes fall naturally into place. I say "invented", but realise there's nothing new in cycling and daresay others have laced wheels this way before me, yet I've never seen my cluster method written up.

How I do it is by alternately lacing the pairs of trailing and leading spokes that cluster in a gang of four where they cross just before the rim. Look at any tangent spoked wheel and you’ll see these clusters. The valve hole should lie between two of them, so that’s where I start.

I find it most convenient to stand the rim in a part-open drawer and hang the hub off the spokes. I start with the valve hole at the top and add spokes to the right of it, i.e. clockwise from there, turning the wheel anticlock from time to time so the hub is always suspended okay. I build rear wheels and most front wheel likewise with the chain side of the hub away from me. But if it’s front hub with a disk or other brake on it, I put the brake side away from me.

The first spoke to fit is an inside spoke immediately to the right of the valve hole, coming from whichever side of the hub corresponds with the rim hole stagger. “Inside” means the spoke lays against the inside of the hub flange and inside most of the spokes it’ll cross, but you feed it into a hole from the outside and that's where its head ends up. Attach a nipple – just a couple of turns – and let the hub hang.

Now fit the next spoke away from the valve. This is another inside spoke and must be threaded into the hole in the opposite hub flange that’s just a tad clockwise from the first spoke.

Inside spokes are the hardest to fit at the end of the process because you have to bend them inside the basket formed by all the other spokes. So assuming a typical three-cross wheel: I fit another pair of them already. These go into the hub and rim to the right, i.e. clockwise, from the first pair, leaving one empty hole in each side of the hub and two empty holes in the rim. If the wheel will be more than three-cross, fit further pairs of inside spokes until you’re one pair short of the number of crossings. (So if the wheel is to be two-cross you will skip this stage, and if its one-cross or radial you’d better use a totally different method!)

With three-cross and two inside pairs now fitted (or two-cross and one pair – etc.), you’re ready to fit a pair of outside spokes. Identify the very first spoke you fitted right next to the valve-hole. Thread an outside spoke into the hub immediately adjacent to this spoke and to the left, i.e. anticlockwise, of it. Twist the hub clockwise and cross this new spoke over all those already fitted. Secure it to the rim beyond those spokes (i.e. to the right, clockwise from them) leaving a gap of four empty holes. Fit an outside spoke to the opposite side of the hub likewise (adjacent and anticlock from the first inside spoke on that side) and attach it to the rim just beyond the first outside spoke.

Now fit a further pair of inside spokes, laying them over the outside spokes just fitted and attaching to the rim via the nearest (clockwise-most) of the four empty holes. You now have your first complete cluster of four. Shift the rim anticlockwise so it’s at the top.

To make the next cluster, fit a pair of outside spokes in the first empty hub holes clockwise from the pair of outside spokes just fitted and attach to the rim likewise but leaving two empty holes. Fit a pair of inside spokes to the hub, clockwise from all those already fitted, leaving an empty hole in each hub flange, and attach to the empty rim holes you just left.

Fit another cluster just like that. And another. See how the spokes naturally fall into a “woven” pattern: with each inside spoke mostly overlaid by outside spokes, but laying over the last one it crosses before the rim. This works until you run out of holes for inside spokes. The last few outside spokes have to be poked around the back of the inside spokes you fitted right at the beginning. But that isn’t difficult and doesn’t call for a whole lot of bending.

If you oriented the hub as I suggested at the start and followed this method exactly, you’ll have a symmetric wheel in which all the spokes that are subjected to the highest tension are outside spokes, which get better support from the hub flanges.

I know it’s a really techie method, but that’s me!
Chris Juden
One lady owner, never raced or jumped.

rogerzilla
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Postby rogerzilla » 19 Dec 2008, 7:47pm

The reason I like to build one side at a time is simple: as soon as you get the 10th spoke in place (for a 36-spoke wheel) the hub is fixed in position rotationally and doesn't keep twisting, making it hard to get the next spoke in.

Cyclenut
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Postby Cyclenut » 19 Dec 2008, 10:27pm

My method is also very tidy. The hub hangs okay right from spoke two and assumes near enough its final orientation just as soon as the 6th spoke is in (a 3-cross wheel). So that's four spokes sooner!

But you do need a part-open drawer to support the rim, and maybe not everyone has one of those?
Chris Juden (at home and not asleep)

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Postby bailout » 19 Dec 2008, 11:07pm

Interested to hear how the op copes with the truing stage :)

I really need to replace the rims on my wheels or get new wheels. Doing it myself is initially appealing but I can't help thinking that if I do I will probably wish that I had just paid someone else to do it by the time I had finished or would waste a lot of tme getting frustrated and take the bits in to a shop.

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Postby meic » 20 Dec 2008, 3:09pm

It helps a great deal if you can have plenty of "time off" from the wheel building during the trueing stage.
As I tend to be building spare wheels or have another bike to ride, I can take my time. I assemble the wheels one day and put it aside for a couple of days. Then I true it so it is roughly rideable and put it aside again.
When I am nicely fresh and relaxed I make the wheel "perfect".

I am not sure about using guages to check the accuracy of your wheel build. I imagine that the wheel will settle in during its first few rides so it would be a waste of time prior to that.
Also it will be flexing and distorting in use in a magnitude that makes using a dial guage level of accuracy a waste of time.
You see a lot of people riding bikes with visibly out of true wheels and it is hard to believe that an imperfection that you can not even see is worth correcting.

This could ruin my reputation as a manic perfectionist!!!

On that point I have had some rims which have driven me crazy because they would NOT go true. If you have tighter clearances then more rims will be insufficiently precisely made to possibly reach the required level.
Yma o Hyd

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Postby Cyclenut » 20 Dec 2008, 6:16pm

bailout wrote:Interested to hear how the op copes with the truing stage :)

I really need to replace the rims on my wheels.

If just replacing a rim, make sure the new one is the same overall depth and tape it to the side of the old one. Then you can simply transfer the existing spokes over. Slacken them all first, by one turn starting and ending at valve, then two turns, then more until they all hang loose.

To avoid getting in a mess when tensioning a wheel, initially screw each nipple on the exact same small number of whole turns, say four. Then, when all the spokes are attached, tighten by one turn at a time starting and ending at the valve hole. (If the wheel is really sloppy, you could make that two or three turns the first time around.)

When you get to the stage where all the spokes are just barely not loose anymore, check the radial (up and down) truth and give another full turn to even numbers of spokes in zones that are high. You'll have to go around the wheel and possibly tighten spokes in the same area several times. If in the process you find spokes that are much looser or tighter already than their neighbours, try to even up those differnces.

This tension balancing is best done whilst none of the spokes have much tension at all, since the rim (which presumably is a true circle) is still dictating the shape of the wheel.

When radial truth is good to within 1mm (any less is unnecessary perfection, since tyres don't seat and aren't made that accurately) you can attend to lateral truth. Take out the left and right high spots by tightening individual or groups of spokes on the opposite side, just half or a quarter of a turn at a time.

People get into a mess truing wheels when they overdo the lateral adjustment, turning in small hop to one side into a big hop the other way! Next comes an even bigger bow in the original direction!!! The key thing is to adjust the nipple less than enough to correct the error. How little that is depends on the relative stoutness of rim and spokes. A narrow road rim is very sensitive to plain gauge spokes, whereas you'll need to take more turns on a double butted spoke to shift a wide mountain-bike rim.

If you have a big lateral error to correct (more than 2mm), it may be worth slackening a few spokes on that side as well as tighening on the other. But it isn't essential, since the radial truth of the rim is so much less sensitive to such adjustments.

Whereas a whole turn on several spokes pulls the rim down less than half a mm in the radial direction, do the same on a single spoke and it'll shoot sideways more than 1mm, maybe 2 even! So whilst whole turns are needed for any measurable effect in a radial direction, it comes down to fractions of a turn with the lateral truing.

But not yet. Once the hardly-tensioned-yet wheel is true to 1mm laterally, check the dishing. Depending on which way and how many mm the rim has to go to become centred between the hub locknuts, tighten only the spokes on that side by one full turn. Measure how far the rim has shifted meanwhile and repeat on this side or both sides by whole or half turns as appropriate, simultaneously putting on the tension and drawing the rim into a central position. When the spokes ring when plucked like a good one should (compare with similar professionally built wheels) stop tightening.

Go around the wheel (starting after the valvehole) grasping and squeezing each cluster of four spokes at their mutual waist really hard, so it hurts your fingers. This beds them in, each one differently, so the wheel will now be out of true. So re-true it. Remember, in fairy steps!

Check the dishing again, on a back wheel the tight side will probalby need another quarter turn or so now.

Whereas near enough really is good enough in the radial direction, precise lateral truth is important for operation of rim brakes. You don't need dial gauges. The final finest truing, to a fraction of a mm, is done by feeling rather than seeing the rim brush the side of your thumb, then tightening an opposing spoke by a smaller fraction of a turn. If you have hub brakes on the other hand - don't bother!

Hope this helps.
Chris Juden (at home and not asleep)

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Mick F
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Postby Mick F » 20 Dec 2008, 6:23pm

CJ.
Brilliant!

Thank you.
Mick F. Cornwall

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robwa10
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Postby robwa10 » 22 Dec 2008, 9:35pm

bailout wrote:Interested to hear how the op copes with the truing stage :)


Well everything went well. I didn't get a dial gauge in the end. When I build my own truing stand I'll probably fit a dial gauge to it though. But mainly because I would prefer it for other reasons than trying to get the wheel 'exactly' true.
Mainly I had to remember that tightening a spoke not only moves the section of rim it's attached to but also around that section. And make sure you don't chase uneveness.

One interesting thing that happened though whilst doing the rear wheel. I reckonend that the spokes needed about a half turn to bring it up to a good tension so went all the way round making that adjustment. Then I found that the wheel had moved out of dish, away from the freewheel. All spokes had been turned the same amount and the rim had been dished perfectly. Why'd it happen? If anything I would have thought it'd gone the other way since the freewheel side spokes are plain gauge.

And thanks to everyone who's added or commented on this thread! There's some good advice and knowledge building up here. :D

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CJ
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Postby CJ » 23 Dec 2008, 9:21am

robwa10 wrote:One interesting thing that happened though whilst doing the rear wheel. I reckonend that the spokes needed about a half turn to bring it up to a good tension so went all the way round making that adjustment. Then I found that the wheel had moved out of dish, away from the freewheel. All spokes had been turned the same amount and the rim had been dished perfectly. Why'd it happen?

The spokes on the slack side, away from the chain, slope more to the side, so any shortening of those pulls more in a sideways direction.

If the right spokes were heavier than the left spokes in proportion to the amount of dish, i.e. a perfectly balanced design, you're correct to suppose that this would not happen. What this shows is that pairing plain gauge with double-butted - whilst undoubtedly an improvement - isn't enough to balance the dish. To do that you'd ideally pair single-butted with a more extreme double-butted.
Chris Juden
One lady owner, never raced or jumped.

pigman
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Postby pigman » 23 Dec 2008, 9:31am

CJ wrote:The spokes on the slack side, away from the chain, slope more to the side, so any shortening of those pulls more in a sideways direction.


learnt something again - cheers!

I was thinking it was down to a subconscious unequal tensioning because the slack side is easier, so your hand inadvertedly turns that bit more.

arc
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Postby arc » 23 Dec 2008, 10:09pm

Excellent guide - wish I'd read it before I rebuilt my wheels. Quick question - what are peoples' opinion on wheel jigs vs using an upside down frame as a jig? I used the upside down frame and, whilst not perfectly true (+/- 1-2mm), the wheels are there or there about and survived their first 40mph descent today (Crow Rd in Campsies so down to gravity rather than my legs ability to pedal). If a jig is the best answer which is best value?

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Mick F
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Postby Mick F » 23 Dec 2008, 10:22pm

Most of my wheels have been built with an upside down frame. I bought a Minoura Jig secondhand recently, and although it's far more convenient with a jig, it doesn't make a better wheel IMHO.

The jig has micro adjusters for radial and lateral checking, but the rigidity of it is quite lacking. Consequently you have to be quite delicate with your hands to stop it wobbling. A frame, on the other hand, is solid and strong - all you need is an accurate thumb.
Mick F. Cornwall