Wheelbuilding

I don’t knit, but if I did I think it would feel like building wheels.  It’s methodical and repetitive.  The end product looks good and is really useful.  It’s a great thing to do planted in front of the TV–  you have a shiny new wheel to show for your otherwise wasted evening.  Building your own wheels opens up infinite possibilities in rims, hubs, spokes, spoke patterns, and colors,  and the end product is stronger and stays truer than any machine-built wheel.

I’d like to say that as a veteran of around fifteen beautiful wheels, I’m a bit of an expert on the topic.  But the truth is I glommed on to a spoke-by-numbers methodology and have doggedly followed it ever since.  While my wheelbuilding technique may not be nuanced, I’ll be damned if the wheels I’ve produced haven’t turn out really well.  One set is about to turn 20,000 miles with nothing more than a minor (and unnecessary) truing before I took a big cross-country tour on them.  They appear good for another 20K.  I use beefy rims, and smaller wheels are inherently stronger than bigger ones, but whatever the reasons I’m happy with my wheelbuilding process.  And I’m proof that anyone can do it.

I’ll walk you through the steps I take as I build up my Alfine-11 wheel.  I’ll try to limit this to just the highlights of my rote process.  For more depth see Step 1.

Step 1 – Buy a Book

I didn’t actually buy mine—a friend gave me a copy of The Art of Wheelbuilding by Gerd Schraner and I’ve never given it back.  It’s thin, well written, and much of it is an arcane but impassioned dive into details that don’t matter much for a typical trike wheel.  It’s a fun read but you can also skip to his “spoking SCHRANER’S WAY” section on page 67.  For all the theory (an even better read), find The Bicycle Wheel by Josh Brandt.  And to just cut to the chase, Sheldon Brown / John S Allen have a thorough online treatment.

There are a few other things you’ll need.  I use a Park truing stand but if you’re handy you could cobble up something that would do the job.  You can even true a wheel that’s attached to your trike but I prefer to pull this process indoors where a trike is pretty unwieldy.  All you need is something to hold the wheel while you spin it and a piece of metal that can be moved very close to the rim and locked in place.  As you spin the wheel, the sound of metal scraping against metal makes it easy to spot where the rim is out of true and needs to be adjusted. You’ll need a spoke wrench.  I prefer a wrench like this one that is dedicated to one nipple size (3.96mm if you’re using 2mm straight spokes, about the only choice for 20” wheels).  You’ll need a small flathead screwdriver to quickly turn the nipples onto the spoke ends before tensioning.  I use a drop of Phil Wood’s Tenacious Oil to lubricate each spoke thread before threading on the nipple.  I also have a box of spoke thread locker that I’ve never felt the need to use.  I use a Park tension meter to measure spoke tension but of course now they have an app for that (iPhone / Android, I’ve never tried either).  If you need to dish the wheel, a wheel alignment tool is handy but can also be worked around with a little craftiness.  I’m not that crafty—I like my tools.

Step 2 – Pick your Components

The sky is the limit for hub and rim choices.  Just make sure the number of spoke holes in the rim match the number of holes in the hub SmileUnless you don’t want to!  For this example I’m building up an Alfine-11 Di2 hub.  The only rim I’ve ever used is the Sun-Ringle CR-18 406, usually with 36 holes.  Occasionally I’ve not found 36-hole hubs and had to settle for 32 holes. Wheels on a non-lean-steer vehicle like a trike must withstand side loads that a bike wheel never sees.  For this reason I use beefy rims and 36 holes (usually).   This may be a little bit overbuilt but I’d rather err on that side.  Until recently I believed that cross-3 meant stronger but I’ve been corrected on that by none other than John S Allen, among many other things keeper of the excellent Sheldon Brown website.  Every wheel I’ve ever built has been cross-3 including this one, but read on to see why this may not always be the best choice.

Even though I do fret over weight I’m obviously willing to live with it if I can see a good enough benefit.  Honestly that’s one of the many liberating things about riding a recumbent—they’re inherently heavier than an upright bike so judicious addition of weight doesn’t feel quite so bad.  Ultimately the weight difference between overbuilt and underbuilt wheels is pretty small. The CR-18 rim is a super strong double-wall design that is still reasonably light.  It’s served me well for over ten years.  My only complaint is that it’s more difficult to get tires on and off of it compared with some other rims I’ve used (on wheels I didn’t build).  It’s also sometimes difficult to find.

Step 3 – Calculate Spoke Length

Spoke length is a mathematical function of Effective Rim Diameter (ERD), hub flange diameter and offset, number of spoke holes, number of crosses, and spoke diameter.  There are a number of spoke length calculators on the web.  I think the best is Spocalc, I use a version I modified to run as a web application.  This spreadsheet has a database of hubs and rims to which I’ve added the components I need for this build (the rim was already there).  It’s usually easy to figure out the parameters for the database from component datasheets but sometimes it’s necessary to measure the parts.  And I sometimes measure them anyway to double-check what’s in the database.  I’ll leave it to Damon Rinard, creator of Spocalc, to explain how to measure hubs and rims. Selecting these from the drop-down menus at the bottom and specifying the number of spokes yields the following results.  Note the spreadsheet lets you specify a front and rear wheel at the same time, a little weird for a trike like this one with two different front wheels.  I threw in the SON dynamo hub for the front wheel but what we’re after right now is the rear.

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Note the OSB setting for the rear wheel.  This is the dishing distance specified in the Alfine-11 specification.  The parameters in the database assume the wheel will be dished.  Because ICE designs their rear dropouts to eliminate dishing the wheel,  I set OSB to the dishing distance to eliminate dishing in the spoke length calculation.  I know this value is correct because the left and right side spoke lengths are equal.

Spokes are sold in multiples of 2mm.  I’ve found it works best to round down unless the result is very close to the next higher increment of 2mm.  In other words, err on the side of shorter rather than longer.  So reading across the 3-cross rows I’d choose 182mm for the front and 180mm for the rear. Most of my wheels were built with DT-Swiss spokes and I’ve never had a problem with them.  Lately though I’ve been using Wheelsmith because they’ve been easier to find.   I don’t have enough time on the Wheelsmith spokes to say how well they work but I don’t anticipate any problems.  Besides, Peter White has a lot more experience building wheels than I do and he now prefers Wheelsmith.  I use straight (not butted) spokes—in these short lengths I think that’s the only choice.  I use the brass nipples that come with the spokes.  And by brass I mean the material, not the color.  Brass nipples match the color of the spokes, in my case shiny silver.

Step 4 – Spoke the Wheel

This is where Schraner’s book shines—in seven spiral-bound, clearly illustrated pages you’ll go from a fistful of spokes and a rim to a wheel ready to tension.  I’ll leave the details to him but offer up pictures of each step. One thing I eventually learned and will pass along:  You can get pretty far along with the tensioning without ever cracking a measuring instrument, spoke wrench, or truing stand.  As you install each spoke, use a flathead screwdriver to turn the nipple until the spoke pops through and prevents the blade of the screwdriver from entering the slot of the nipple.  Once you’ve done this with all the spokes you’ll be at a reasonably true starting point to begin the final tensioning and truing steps.  If the spokes are on the short side of the calculated ideal spoke length, you’ll be starting with a reasonable amount of tension already.  If really short you may not be able to do this trick for all the spokes because the tension will be too high.  In that case you’ll want to back off a little on the spokes already installed to get the starting point for tension a little more uniform across all the spokes.

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Steps R1, R2

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Steps R3, L1, L2

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Steps L3, L4

Step 5 – Set initial Tension

If your rim is true and you were careful to turn each nipple roughly the same amount, the wheel should be true-ish after spoking.  Before breaking out the tensiometer I usually continue to tighten the spokes evenly until they’re getting a little hard to turn.  This works particularly well if you don’t need to dish the wheel—if dishing is required you’ll want to start paying attention to the offset a little sooner.

At this point I throw the wheel on the stand and do a quick check for true.  If there are major wobbles I adjust them out and then check for proper dish with the alignment tool.  Then I check tension on each spoke with the tensiometer, entering the readings into my spoke tension calculator.  To keep the tensions straight and allow evening them out later in the process I label each spoke on the inside of the rim with a permanent marker.  1L through 18L and 1R through 18R for a 36-hole wheel.  Then, if I need to adjust the offset (dish), I use the following guidelines.

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Now the tensions might look something like the following screenshot from the calculator.  This is actually taken after a couple of iterations of tensioning and checking tension.  Often the first pass at checking tensions have several Kgf readings with a red block instead of a number, meaning the tension is way under the limit.

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Note that the difference in average tension shown in the screenshot implies some amount of dishing is present.  This happened because I was using the alignment tool to try to keep the wheel centered and used the wrong reference on the drive side.  Normally you just pop the tool back and forth on the left and right sides of the wheel and adjust until it shows the same distance to the nut that the dropouts clamp too.  But without the Alfine  shift motor installed you don’t actually have the correct reference on the drive side.  If I was sure I didn’t need any dishing, the usual case, I’d just keep the average tensions the same on each side and not use the alignment tool.  Because I’m unsure about the Alfine hub I’ll just have to install it on the trike and measure how far off of center I am and then adjust it out on the truing stand.

As I’m iterating through adjusting and checking tension, I look for big variances between spokes (lit up in red in the spreadsheet) and try to even them out without de-trueing the wheel.  For me this is more of an art than a science and it can be a little frustrating sometimes.  While the goal is even tension across a perfectly true wheel, I’ve never made all the red go away on the spreadsheet.  I just try to knock down the big differences and then stop when the wheel is true.  With this technique it’s not difficult to get a perfectly true wheel and I’ve never had one of these wheels fall significantly out of true during use.  Except a couple on a trike that was run over by a car but that’s another story…

Before checking tension I always relieve stress on the wheel by holding it in my lap and pressing fairly hard on opposite edges, repeating through several positions around the wheel.  You’ll usually hear numerous snaps and clicks as the the spokes “un-twist” in the eyelets and/or nipples and tension is relieved.  When you no longer hear the clicks, tension is relieved.  Not doing this runs the risk of having the tension released while in use and your wheel going out of true.  Schraner has a good description of this on page 85.

I think I may be tone deaf.  A few years ago my friend Chip tried to convince me that I could check the tension by ear.  Just pluck each spoke and listen to the tone, adjusting tension until all tones are the same.  Of course the science is sound, the greater the tension the higher the note, but who can actually distinguish such subtle differences in pitch by ear?  Having played with this over the course of building several wheels I’m still not convinced—there’s no way I can do as good a job by ear as my trusty Park tensiometer.  But apparently there are others who can.

Step 6 – True the Wheel

Once you’ve got the wheel at about the right tension and offset/dish it’s time for the final truing steps.  This is an iterative process—check true, check tension, adjust, repeat.  There are two types of errors that must be trued out of the wheel—out of round and lateral wobble.

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On the Truing Stand

Adjusting the wheel to be perfectly round is the most difficult so I usually start there.  This involves setting the caliper tips of the truing stand so that they just barely touch the outside of the rim—the part that faces the ground while rolling.  Rotate the wheel and stop it wherever the rim rubs against the caliber.  These are areas where the rim needs to be pulled inward to a smaller diameter.  Pick an equal number of left and right spokes near this spot and increase tension equally on the left and right sides with the spoke wrench. How much to turn the nipples depends on how bad the wobble is but usually small adjustments work best, probably a half turn or less.  You can also release tension in areas where the rim is furthest from the caliper but these are harder to detect.  Depending on how “sharp” the wobble is you can choose to adjust one or more spokes on each side of the wheel to adjust through smaller and larger portions of the rim.

Once the wheel is round, adjusting out lateral wobble is easier.  It’s basically the same process but with the calipers adjusted to just barely rub on the left or right side of the rim.  By switching back and forth from the left and right calipers you can easily detect sharp wobbles in either direction.  To correct a wobble, decrease spoke tension on the side that scraped the caliper and increase tension on the opposite side.  Adjust as many spokes in a row as needed to cover the area and sharpness of the wobble, and for very sharp wobbles you can adjust an uneven number of spokes on the left and right sides.  Just make sure that between all of the spokes adjusted for one wobble, you turn the spoke wrench an equal number of turns on the left and right sides so that the wheel remains round.  For example, if you adjust two spokes 1/4 turn tighter on the right side, adjust one spoke 1/2 turn looser on the left.  This is an example of a very large correction– even more than when adjusting for round, a little adjustment goes a long way.  Usually under 1/4 turn in the final iterations.

If this all seems tedious and time consuming, well, it can be.  But don’t fret, by making small adjustments and frequent checks on the truing stand you’ll quickly iterate to an extremely true wheel.  If you make a mistake and over-correct, making the wobble worse, it will quickly get straightened out in future iterations.

When am I Done?

You’re done when the wheel is perfectly true and tensions are perfectly even across all the spokes.  Or you run out of patience and time.  And maybe on your first wheel: after throwing it across the room, killing the cat.  I find padded rooms are best.  Remove all sharp objects.

This is where perfectionism may not be your friend.  I stressed over this on the first couple of wheels, drawing out the process into several evenings.  I eventually learned that a slight wobble, indicated by an occasional, ever-so-slight rub against the caliper, isn’t even remotely noticeable in the real world.  Your wheel will look and feel perfectly true.  As for perfectly even spoke tensions, well, good luck with that.

The cat survived.

Oops

Now I’ll illustrate one of my first assertions, way back at the beginning of this overly long post.  I’m no expert at this.  An expert would have recognized before purchasing the spokes and building up a wheel that a cross-3 spoking on a hub with such a large flange diameter and width will yield scary-looking angles between spoke and rim.  I’ll leave the explanation to the experts, but take a gander at these pictures.  Scary, huh?  In fairness, the angle is pretty severe even with small hubs when using cross-3 spoking on a 406 rim and I’ve never had a customer complaint.  And I’m very close to my customer.  But this is too much even for me.  I’ll be rebuilding the wheel with cross-2 or maybe even cross-1.  No worries, I know the drill.

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Severe spoke angle at rim, spoke bending around flange on hub

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