Wheel Building Experiments: Perfecting Spoke Thread Prep

Today, children, in pursuit of the 100% Grade A pasture raised bicycle, we’re making our very own all natural, organic, food grade, flax oil (or linseed oil) spoke thread preparation. Or that’s the hope. And what the actual fucking why, you might ask? Let’s dig into it. 

I’m building a wheelset for myself, and trying to select the best spoke prep. And lacking any alternatives, I’ve made the dangerous choice of turning to the internet for information. According to a random website I found purporting to display the transcripts of some missives between the wheel curious and wheel building wizard, Mr. Jobst Brandt (author of The Bicycle Wheel, the seminal text for would-be wheel builders), there’s no justification except laziness and ignorance for using what he disdainfully refers to as “glues” on spoke threads. The only thing you need for spoke and nipple prep is a little waterproof lube (the master’s preference: crank grease and motor oil). Furthermore, these treatments aren’t meant to provide any kind of thread locking properties (so no Loctite), merely to lubricate the threads and nipple seat at the rim to provide easier nipple turning, less spoke wind up, and thereby faster and more accurate optimum torque and tension. Cool, cool.

In my limited experience I’ve used boiled linseed oil, Wheel Fanatyk FIX, Wheelsmith Spoke Prep, Wheel Fanatyk Clear Building Oil, DT Spoke Freeze, and just plain old Tri-flow (no automotive lubricants, dilatant that I am). But boiled linseed oil is what I’ve used most and know best. I built a wheel with FIX that came fully detensioned on the rider’s tour in Alaska where a constant downpour appeared to have rinsed any evidence of the treatment off the spoke threads. I may have an idea about the reason for the disappearance: Wheel Fanatyk’s  website says FIX is water based (it looks and feels like water based latex paint), and therefore one can suppose it may not entirely resist dissolving in water, particularly if somehow it isn’t fully cured.

I’ve also seen a wheel (granted, a ten year old build) put together with Wheelsmith Spoke Prep come completely detensioned in much the same way. Not my build this time. The advice of the sage says that a properly built and tensioned wheel won’t have spoke threads backing themselves out. If we take Jobst Brandt (or someone pretending to be him on the internet) as gospel, then it was entirely my fault—and the fault of the builder of the ten year old wheel—that those wheels came detensioned, not the failure of a particular spoke prep. They were bad builds. No spokes broke. They didn’t wear out from rough use. They just slowly came undone (or rapidly in the case of the Alaska tour).

Funny thing though: I haven’t had the same experience with linseed oil. Wheels that I’ve put together with linseed oil have tended to stay put together. I don’t have a scientific study with a massive sample size, or even decades of wheel building experience. I accept that my preference for linseed oil could be based on coincidence, and inexperience. And poor execution may really be the only reason behind wheels with FIX and Spoke Prep coming apart (admittedly a bit harder to accept). 

But I’d like to think that I’m meticulous when building wheels. My guess on the Alaska job is that if I’d had the opportunity to tension the wheel back up after a week or so of regular use, it would have stayed together on the tour (I built it only a week or two before it was under the weight of a fully loaded touring rig and rider without a break-in period or seeing a truing stand again). But that just goes to support the theory that it was a poorly put together wheel, the fault of the builder (me) and the process. Knowing that I wouldn’t see the wheel for a re-tension, I should have more thoroughly stress relieved the spokes and spent more time getting them to absolutely max optimum tension. This is a good lesson. Perhaps the linseed oil is a crutch (even if it’s also a placebo), and I’ve since been spending more time stress relieving wheels during final tension in general. 

In the meantime, I think I’d prefer to steer clear of spoke thread treatments I’ve had bad experiences with, and continue to refine my process. And that brings us to our current spoke prep experiment. I’m heating dietary supplement flax oil to see if I can accelerate the drying process.

That’s the idea behind linseed oil as a thread prep (also as a wood finish). It’s a drying oil, meaning that it polymerizes. It reacts with oxygen and overtime forms polymer chains and slowly hardens. As an oil it’s also hydrophobic even before it fully polymerizes. So water shouldn’t be much of an issue. Or that’s what all I’m led to understand. I’m no chemist.

In the past I’ve used what’s referred to as boiled linseed oil, which I guess isn’t actually boiled. It has heavy metals, solvents and chemical drying agents added to accelerate polymerization. Convenient, but also maybe a bit nasty (and a lot more volatile). I’m hoping we can make a better boiled linseed oil with heat rather than heavy metal. And the closest I can get to a good reason is that after all my internet research, spoke preparation feels like the wild west. So why not add to the noise.

The ideal consistency for linseed oil as spoke prep is almost a gel, not fully polymerized (obviously that would be solid). We’re aiming for just tacky enough to coat the threads well and stay in place during the wheel building process, but not so stiff that it at all interferes with threading the nipples onto the spokes. We’re making flax oil jam! It should basically act like a thick lubricant, a la crank grease (Jobst Brandt [or internet proxy] you’re never wrong) on the threads.

RESULTS: uncertain (failure). I’m too impatient to watch flax oil dry!  24 hours on the heat, with no discernable thickening. Back to the drawing board, I guess. Maybe we should just use motor oil and crank grease (it’d be easier). How about we revisit this in a month.