wheelbuilding question

[neptune]

As part of my resolution to spend more time on practical things, I am studying the theory of wheelbuilding, prior to having a go in practice. In the process of resurrecting some bikes for the grandchildren, I have trued up a couple of wobbly wheels, and the process has worked well. My next project is to completely strip an old wheel down to the hub, spokes, and rim, and then rebuild it. I am jumping in at the deep end, by rebuilding a rear wheel, which is dished. I have made a wooden jig to measure the amount of dish, so I can reproduce it.

So my question is this. On a dished rear wheel, are the spokes the same length on the right side of the wheel as they are on the left?

I assume that on a wheel with a hub brake or a hub dynamo, as the flanges are of unequal size, different length spokes are used for left and right?

 

[awol]

It depends on whether the holes on both sides of the motors flanges are the on the same diameter. If they are then the spokes will probably be 2mm different in length, however like the 8fun cst motor which has the holes 2mm difference in diameter from one flange side to the other those spokes will all be the same length.
Here is a useful website about spoke lengths.
http://www.wheelpro.co.uk/spokecalc/

 

[neptune]

Awol. Thanks for the info, and the link. I know this is a pedelec website, but I need to walk before I run, so I am starting with a rear wheel from a derailleur equipped pushbike. I suppose that the same principles apply.

 

[awol]

Yes the same info applies, just replace the word motor with standard hub.
Also search for 'Sheldon Brown' for another excellent website with everything you need to know there.

 

[neptune]

Been busy fixing bikes for grandchildren and various random people. So back to wheel building. I have a wheel in my workshop. It is a rear wheel that is designed for a six speed derailleur freewheel. Unsure of the wheel size, it is about 22 inches diameter. I took two spokes out, one from the drive side and one from the other side. They are of different lengths. One is 2mm longer than the other, the shorter one from the drive side.

Everyone says that to order spokes, you measure from the tip of the threaded end, to the elbow. Spokes appear to be specified in various lengths, varying by as little as 2mm. So do we measure from the inside of the elbow, or the outside?

Then there is a question of wire gauge. I have a new spoke key that fits a number of sizes, designated by numbers such as 12, 13, 14, etc. Do these represent wire gauge numbers? The spoke nipples in this wheel are size 14. Does this mean that the spokes are 14 gauge? Or can a "14 size nipple" fit spokes of a range of sizes?

I know that some firms ask you to send a sample when ordering spokes. But there seem to be more questions than answers. Can anyone answer my questions please?

Added later.Internet research tells me that spoke length is measure from the inside of the elbow. So if you use a steel tape measure, you hook the head of the spoke over the end of the tape at the very edge of the tape, That way you can avoid the sliding clip at the end of the tape. The length can then be directly measured against the millimeter scale. Still looking for answers about gauge and nipple sizes.

 

[awol]

To get the same spoke gauge you are better measuring the spoke diameter, then order with matching nipples. i.e cycleclinic or tiller cycles or ebay.

 

[jerrysimon]

I cut my teeth on wheel building by first downloading the wheelpro manual on the spokepro calc site, everything you mention is covered in there. The late great Sheldon Brown's site also helped me alot too.I started with small wheels which I think are easier, especially if you lace them radially

It is such a satisfying skill to master. Well I say master, but to be honest I am not sure anyone ever masters it completely. Each time you build a wheel you learn something new. Most often its a compromise (I am not sure its possible to build a perfect wheel) between the various elements of tension and lateral, dish and roundness of the wheel. Although spoke length calculators help there are often many additional factors with building wheels to incorporate motors as the Chinese made hubs vary in terms of consistent measurement and flange hole drillings of the same hub over and above conventional wheel hubs. Its a little bit of trial and error until you can get exactly the right sized spokes. This is probably more true for smaller wheels. I always record spoke lengths for future more accurate builds of the same motor hub and rim.

Initially I got lots of help from this forum and later was fortunate to exchange many many emails with an experienced wheel builder, catsnapper (Alan) on here.

PS You are brave to start with a rear dished wheel, I personally would always recommend starting with a simpler front wheel build. I guess as you are taking apart and rebuilding an existing wheel it's probably not as bad as starting from scratch.

Regards

Jerry

 

[neptune]

Jerry, many thanks for useful input. A quote I like from the Sheldon Brown website. "The Perfect is the enemy of the good". What a brilliant theory for life, never mind wheel building. I am starting with a dished rear wheel, as that is what I have. It is surplus to requirements, so if I end up with a mess, I have lost nothing and gained experience. I intend to reuse the same spokes, as the wheel is not very old, and will probably never be used as a wheel again. So I know I have the right spokes. My other questions were for "next time". I have also learned that, at least on this particular wheel, the drive side spokes are 2mm shorter than the other side, to help with the dishing.

 

[awol]

I cut my teeth on wheel building by first downloading the wheelpro manual on the spokepro calc site, everything you mention is covered in there. The late great Sheldon Brown's site also helped me alot too.

Jerry, how would you find the wheelpro book from a point of view of someone who has already built a couple wheels? I have recently been tempted to buy it but not sure if it will help or there is anything else it could tell me other than more practice of the same needed.

 

[eHomer]

I built my first wheel from scratch about 3 months ago, after Dave egged me on.

It was a Q100H hub into a 700c rim, and it turned out very successful, so I wish I'd been braver sooner.

I had previously replaced spokes, trued wheels, and altered dishing by about 1" on a pre built BMS wheel that had been centered wrongly, but had always shied clear of building from scratch.

I found it much easier than I expected, thanks to the already mentioned Sheldon Brown online guides and various Youtube videos.

I initially tried using the 13g spokes that were supplied with the hub motor, but as I had been advised (and had ignored), they did make the job very difficult because they were so tight in the hub holes.

When I tried again with 14g spokes it was a doddle, and the wheel turned out true within half a millimetre, and nicely tensioned up after I read about "pre-stressing" with a block of wood and pad on the floor, (on youtube).

The only crucial point is spoke length, the tolerance is less than 5mm, so it takes no prisoners. It's vital to measure really accurately and use one of the spoke length calculators on the web, and set it for the right number of crosses.

 

[jerrysimon]

Jerry, how would you find the wheelpro book from a point of view of someone who has already built a couple wheels? I have recently been tempted to buy it but not sure if it will help or there is anything else it could tell me other than more practice of the same needed.

Its not that expensive. I read the book to start with and perhaps looking back its a bit over detailed for the first time builder, if you stray beyond the sample build. I think it also starts with a rear wheel build. For someone who has built a wheel the book has a wealth of other info over and above building your first wheel. I often refer back to it. All that said the information is available elsewhere on line plus of course the many youtube wheel building videos.

Jerry

 

[neptune]

Time for an up date on my wheel building project. I am at the stage now, where I have the wheel laced up, but it is still slack and wobbly. Progress has been slow, but for me it is not about speed, it is partly about learning, and partly about having a pass time to fill those idle moments. Some people do knitting, some do jigsaw puzzles, I do wheels. These activities have a lot in common.

Here are some of the things I have learned up to now. Wheel building is partly science and partly art. There are often several ways to undertake a given part of the process. In these cases, no way is right or wrong, but some ways will suit you personally better than others.

In trueing a wheel, you are juggling several interdependent variables, that it where the art bit comes in. Correcting a fault in one department can create new faults in other departments. Patience is the key, and knowing when you are getting too tired, and taking a break.

14 gauge spokes seem to be the most common. These have a diameter of 2mm. A rough and ready guide to the gauge or thickness of a spoke, is to use your spoke key. If the slot marked 14 is a perfect fit on the nipple, the odds are the spoke is a 14 gauge. So different gauges of spoke have their own specific nipple size which takes a specific size of spoke key slot. All this may seem obvious, but it was not obvious to me until I researched it.

I think it pays to watch several videos by different builders, as you pick up tips from each one. As always, Sheldon Brown`s article is the definitive guide. As I said earlier, I now have the wheel laced perfectly. Or nearly perfectly. The valve hole is in the wrong place ! Ever fourth gap between the spokes at the rim has the spokes running parallel as they leave the rim, giving more space to apply the pump. Mine is not.

The wheel would be perfectly useable as it is, but I am tempted to strip it down and try again, If not, it will bug me every time I look at it. It is all part of the learning curve as they say....

 

[jerrysimon]

Yep most of that rings true with me. As I said the different planes of truing are always a compromise.

One thing I learnt after a few builds was always to start with radial truing as this is hardest to adjust once the wheel is tensioned up.

Also once everything is close its easy to just add exactly the same amount of adjustment on each nipple as you bring the wheel up to full tension. Of course destressing is important after each full rotation of adjustment.

The next thing to learn is the initial process when buying a new rim, hub and spokes and making sure you measure everything correctly, so the spoke threads don't poke out of the nipple ends once built or too short that the threads can still be seen as they enter the nipple. That sounds rude or maybe its just my mind lol

Well done!

Jerry

 

[eHomer]

Yes, I also think that radial truing is the hardest knack to learn, and yet it's probably the most important regarding loss of speed and power, due to the increased drag from vertical movement.

It's funny how it suddenly becomes easier though with practice, as you start to take in when to also slightly adjust the diametrically opposite side of the rim when correcting side to side adjustments. A wheel truing stand makes it so much easier, (even a cheap one).

You're dead right about spoke length as well. When you get that right, the wheel is almost true to start with, when initially assembled with the same number of turns on each nipple.

The numerous youtube videos on wheelbuilding also made me aware of the need for pre-stressing the spokes during the truing process, something that very few brand new bikes appear to have had, hence them quickly loosing their tension or even buckling.

 

[neptune]

Thanks for those kind words of encouragement and advice guys. I am in the process of designing and building a wheel trueing stand.The basic structure was completed yesterday, so the glue should be dry by this afternoon. I have made it so I can adjust the width to accomodate different axle lengths.

I had to buy a couple of spokes, or three to be exact, to replace missing ones. The posh local bike shop, who have helped me in the past were out of stock, so I went to an old fashioned LBS down a back alley. Three spokes with nipples for a quid. Incidentally I have learned that as I suspected a dished wheel uses shorter spokes on the drive side.

It may be tomorrow when I get back to the wheel, as I have some chores to do later. Still undecided whether to strip it down, or true it up as is, and then strip it and build it again. I am finding it challenging but very rewarding. Sure beats jigsaw puzzles.

 

[awol]

I am finding it challenging but very rewarding. Sure beats jigsaw puzzles.

I also find the trueing stage to be quite theraputic but the patients of a saint are needed.
I usually spend an hour or so at a time spread over a few days before I get tired of chasing that tiny buckle and make do with it.
Your trueing stand will help for sure, my first wheel was built with a home made stand, if not there a cheap ones available on amazon or chain reactions.

 

[neptune]

There was heavy rain this morning, so I postponed my bike ride until afternoon. So instead, I went in the shed and finished my wheel truing stand. Made from recycled materials, it will not win beauty contests, but is accurate where it matters. It even has a sliding bolt in a slot so I can adjust the width for different spindle lengths.

Instead of stripping the wheel down after getting the valve hole in the wrong place, I trued and tensioned the wheel. It is accurate in radius to within a mm, and true within 2 to 3 mm, as judged by eye. If this was a wheel for one of my own bikes, I would be happy with that. I think that if you fit a tyre, there will be variations in the tyre fitting that would be within 1 or 2 mm, so we have to work within practical limits.

Thoughts on spoke tension. With a perfect rim spokes and hub, it would be possible to have a perfectly true wheel with all the spokes at the same tension. Here in the real world, I don`t believe that is possible. Take a new rim, just how round and true is it? Does the metal have uniform hardness and tensile strength all the way round? I say there will be variations. Therefore, to hold that rim straight and true, some spokes will need more tension than others.

What I noticed about trying to asses spoke tension by musical pitch. On the wheel I have just built, every spoke crosses and touches another spoke about a third of the way along its length. If you twang the outer two thirds of the spoke, you get a sort of semi musical note. But the spoke that touches it, does not push against it hard enough to act like the bridge of a guitar, so the resultant note is damped. I can tune a guitar by ear, but this is much harder. Also for the reasons given in the last paragraph, I do not think uniform spoke tension is necessarily possible. With used components that I have, I can either have a wheel that has uniform spoke tension, or a true wheel.

Incidentally, If we want uniform spoke tension, why are spokes not tightened with a miniature torque wrench. After all, that is how we achieve uniform tension in cylinder head bolts.

I refinement I may add to my truing stand. An arrangement so that I have a piece of spring steel like a feeler gauge that I can adjust to touch the side of the rim. The advantage would be, it would touch the out-of-true point as the wheel is turned, but it would not stop the wheel. With my poor eyesight, it would be easier to hear it touch the rim, than to see it.

These are some of my random thoughts at this stage. All comments welcome. " The perfect is the enemy of the good" [Sheldon Brown]

 

[john h]

As to your refinement you could use an ink marker, it would mark the high spots, given you an idea where to adjust

 

[jerrysimon]

Spoke tension is an interesting topic. Initially I always did mine too high. A good start is to find a similar size wheel with hub spoke crosses etc and ping them. When I started out I use to go round looking at every wheel I could find looking at cross and lace patterns and pinging spokes on all sorts of bikes lol

Mine usually sound pretty similar on a build but I purchased one of these made by park tools just to convince myself that I was getting the tension high enough and consistent.

Once I got it I found most of my wheels were pretty consistent after I did it by eye or should I say ear

I am not sure its really necessary to own one for the hobbyist more if you are building wheels professionally I guess.

What I have noticed however is most factory build wheels are not tensioned high enough, in fact some factory built wheels are terrible. Even more so on Chinese built electric wheels.

Friends at work are always getting me to re true and re tension their factory built bike wheels.

Jerry

 

[neptune]

Thanks for that information Jerry. I had sort of noticed those tension gauges, and wondered about them. Do they measure absolute tension, or is the result just a number so you can compare adjacent spokes? If it gives absolute values, does it come with a table of recommended tensions for different spoke lengths?

My test wheel, when finished had two faults. The valve hole was in the wrong place, and the dishing was about 10 mm out. It would probably have been usable. Anyway, today I totally stripped it down, and rebuilt it. This time the valve hole and dishing are right, and it is true and round. It probably needs a bit more tension though, so I will probably see to that tomorrow. I plan to strip it and rebuild it at least once more. Lacing was much quicker and easier this time. I need to make a better, adjustable dishing stick.

The very best video I have found on wheel lacing is a youtube video entitled
"Without the Bullshit, How to build a 36 spoke wheel" It is by an Australian girl, and is exactly what the title says.

https://www.youtube.com/results?search_query=without+the+bullshit+how+to+build+a+36+spoke