I'm Speaking Spokes
The sticks on your wheels
I know of a man who was a master of his craft. He was one of the premier wheel builders for mountain biking in the region. People as much as 1000 miles away would come to him to have wheels built. I learned about him from a friend of mine happened to have dinner with he and his wife one evening back in the 90’s, when my buddy came to him for a wheel fix. Following dinner, he took my friend back into his shop to watch him build a bicycle wheel before fixing his wheel. During the process he apparently asked if my friend could see ok, and if the light was on. My friend laughs as he describes how he first just nodded, but then realized he needed to answer out loud. Why? Because the master crafter was blind. I forget the specific reason he had lost his sight, but he had it under control.
How did he build the bicycle wheels, if he was blind?
My friend said he had a small workshop that was setup with all the spokes and spoke nipples in boxes within easy arms reach. A couple different sizes were all that were there, and he had a stack of empty rims and boxes of hubs behind him. He primarily worked on road bikes, but would occasionally do mountain bike wheels. He would take a rim, and start threading all the spokes to the hub. For rims that were rim braked, he spoked radially, for rims that were hub braked, he spoked them in a cross-pattern with trailing and leading spokes. He did all of this by feel, but the real magic came when he started putting the tension on the spokes. He started by putting the wheel on a basic quick release mount and he by feel we worked his way around the rim tightening each spoke a specific number of turns. He apparently worked very fast! Once he got around the rim a couple of times (he’d count out loud the rim spokes, to keep track), he pulled out a small rod. While the wheel was spinning, he lightly held the rod against the spokes so they would “clink!” as the rod hit each spoke in sequence. On a new rim, he explained, he could tension all the spokes perfectly by pitch. He knew that a certain amount of tension in pounds equated to a specific pitch. He explained the pitch would be different for each of the rims, based on the spoke count, and sometimes the application. As he tightened the spokes, the pitch would raise (tighter=higher clink sound). My friend said he was working on rear wheel, and told him the spokes on the side of the cranking gears needed to be twice as tight as the spokes on the other side, for optimal transfer of torque. As he spun the wheel when he was finished, the far side went “ding, ding, ding, ding, ding” and the crank side went “tink, tink, tink, tink, tink.” It literally was perfection. He apparently then grabbed the friend’s rim on the bench, put it on the spinner and used a small metal bar to find the part of the rim that was out of true (it would scratch against the metal bar), and he adjusted the spokes accordingly. My buddy said it took him less than 30 seconds to fix the rim and put it back in true. He also noted that he could tell the rim was factory made because of the lousy pitch sounds it made all over… and laughed about it, telling my buddy it wouldn’t kill him, but he’d go ahead and “make it better anyway.” Then he proceeded to tighten accordingly, with the only part now out of perfect pitch the section of rim that needed re-truing (because the pulling of the spokes is what pulled the rim dent back into place).
As I think about this story, I realize that most of us will never likely need a rim that is so perfectly true it dings and clinks with pitch perfection. But the reality is, when it comes to rims, speaking of spoking matters. I’m sure there was other things the craft master was doing that wasn’t explained to my buddy (such as nipple sizing and angles), but the point remains. Spokes matter.
Spokes are what transfer the torque from either the hub to rim (During crank) or from the rim to crank (during rim braking). Spokes also enable distributing load.
Consider the fact that the load of the bike changes when you get on it. As the wheel rotates, the greatest load will be on the spokes pointing downward at the ground. Those spokes will be looser, during ride, and the spokes on the top (directly above the hub of the ones pointing down) will have an equal amount of load increased. Having properly tightened spokes helps you maintain better control of your bike wheel.
In the 1990’s, I walked into an apartment and saw a rim just completely mangled. Apparently, the owner tried to retrofit a rim that previously had rim braking to one that had a hub brake. He had salvaged the hub from somewhere, and thought it would be cool to switch the braking system out on his bike. I wish I’d been there when he actually tried it out. All I got to see was the aftermath. To say it was destructive would be an understatement! The spokes were all bent, the rim was ruined, and the owner had a fair number of new scrapes and bruises. What happened?
Well, the spoke configuration was built for RIM braking. In a rim brake scenario, the spokes are all radially moving out from the hub. This is because the brake force is applied at the outer edge of the rim, the brake transmits all the torque to the frame or fork directly, none through the spokes, the braking system actually is slowing down the wheel rotation at the rim. The whole wheel simply slows down because of the braking force at the rim.
A HUB assembly brakes from the center, which means the rim actually wants to keep rotating while the hub is being braked. Because the spoke configuration was radial, this basically meant the rim was allowed to keep rotating while the hub slowed. The end result is the rim just sort of collapsed on itself, folding inward and the spokes bent and mangled accordingly. This dude learned the hard way that there is a REASON why hub braking systems have spokes laced in a cross pattern. Half the spokes in a cross pattern like this are called “leading spokes” and the other half “trailing spokes” By changing the angle, so they’re not radially setup, the spokes can handle the changes in tensioning during braking.
So, there you have it. It’s not for aesthetics. It’s for SCIENCE.
I speak it now. Spokes matter.
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