Hubs part 3

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Part 3 wraps up the general overview of various hub features and how they work. Hopefully this section gives you all the info you need to be an informed consumer of hubs. 

There are two things I should have discussed at more detail in the previous section on hubs being the anchor point for the spokes, so I'll add them here and then add them there.

1. Flange geometry dictates build stiffness of all wheels, and determines spoke tension ratios of dished wheels (all rears, and disc fronts). In rim brake front wheels, generally speaking more flange spread is better for stiffness. The flange spread creates the base of the triangle, and triangles with wider bases are more stable. In rear wheels, flange spread becomes more problematic. It increases build stiffness, but it decreases tension ratio - the drive side flange can't go farther outboard, so increasing flange spread means moving just the non-drive side outboard. That means the non-drive spokes have less tension. Insufficient non-drive spoke tension creates problems. Same is true of disc front wheels. This is why we like the offset rims in the FSW3 Disc so much - insufficient off-side tension hasn't been an issue in our builds, but we think the equalized tensions in the offset disc builds are helpful in particular for disc wheels, which generally see more stress than rim brake wheels. 2:1 and similar uneven lacings present a few issues that prevent us from being fans. For one, unless you have a specifically optimized hub, they just improve spoke tension balance and do nothing (sometimes negative, even) for build stiffness. For two, they leave a very long unsupported span between non-drive spokes, which can screw with the ability to really nail tension even-ness on the non-drive side. For three, availability of parts to do it correctly is thin.

2. Bearing spread. Subject to a few small caveats, the farther outboard you shove the bearings, the better. This leaves less unsupported axle length cantilevered past the bearings. There are some caveats that we'll get into with each hub in the next parts. 

And now onto Episode 3...

The Transmission

  1. Industry Nine, White Industries, and Novatec hubs use more common pawl/ratchet drive systems. For road, WI and I9 use 3 pawls, while Novatec uses 4. White Industries disc hubs use a 48 point ratchet ring, while I9 doubles the pawl count to 6 on their mountain hubs. This is a reliable and proven system that generally works very well, lasts very long, and is easy to fix if something goes awry.
  2. Chris King hubs use a ring drive system. A spring within the hub pushes a spiral clutch out against a mated surface on the cassette body when you are pedaling, and allows the spiral clutch to push in and allow the hub to spin independently of the cassette body (creating the famous “angry bees” noise) when you coast. This system is more complicated, offers increased ultimate strength, and of course creates a compelling noise.
  3. Engagement speed is a topic that gets a lot of press lately. The more points of engagement that you have, the more quickly your pedaling turns into watts applied to turning the wheel. The tradeoff is that engagement creates more friction when coasting. One way or another, it’s not a huge difference. Because the balance of benefits tips more toward higher engagement being better for mountain biking, mountain bike-oriented hubs have more points of engagement than road equivalents (72 versus 45 for Chris King, 120 versus 60 for I9, and 48 versus 24 for WI – Novatec has the same in both). You will notice a benefit in points of engagement more when you are accelerating from slow speed, or particularly when you are ratcheting your cranks to clear obstacles on the trail. For road, where you are coasting either because you are going through a corner to fast to pedal through it, or because you are going downhill fast enough that pedaling doesn’t make sense, points of engagement generally means bupkus. Except that high engagement hubs can be super annoyingly loud – I love my I9 mountain bike hubs, but on the road that noise would turn good people bad.

 

Transmitting Brake Force from the Brakes to the Tires

  1. Six bolt rotors use – wait for it – six small bolts to hold the rotor onto the hub. This works on any kind of hub and is an open standard, so anyone can make a 6 bolt hub or rotor or lockring without paying any royalty to anyone. Rotors are readily available and can be reasonably inexpensive. photo stolen from White Industries
  2. Center lock rotors use a splined interface, sort of like how you put the cassette onto the cassette body, to mount the rotor to the hub. This is a Shimano-patented invention and, as such, they get a small royalty on every part sold on the standard. For our money, center lock offers a better fit between rotor and hub, and the rotors somehow seem to arrive and stay more true. They’re also a cleaner look. So we prefer them. It’s also easy to use an adapter to put a six bolt disc onto a center lock hub.
  3. Getting your rotors on various hubs perfectly aligned can be a small challenge. 1-3/8” ID x .001" thick shims work PERFECTLY to bump a centerlock rotor outboard in .25mm increments, while 6 bolt shim kits are available at bike shops. Set your brake calipers to the hub/rotor combo that sits farthest outboard, and then shim the others out to that spec.   

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  • Scott on

    Well done, Sir!! Not sure I agree with the minimal benefit of not having to pedal the additional 7.5 degrees to get all my wicked quad power through my bike's drivetrain… (oozing with sarcasm and love for how you guys speak truth)!!!

  • Rico on

    Still bummed that the Nimbus Ti hubs were discontinued. Novatec makes a very decent hub, but the White Industry built Nimbus hubs have been truly flawless,through all manner of challenging terrain and weather. Use a weak thread-lock compound on the Novatec thru-axle adjustment. Don't say you weren't informed…. Hubs do indeed matter: http://www.novemberbicycles.com/blog/2015/7/24/why-hubs-matter.html

  • Mike on

    I love loud hubs, I have Hope Pro IIs on my nicer set of mountain bike wheels, love how they sound. Loud road hubs almost get people's attention better than a bell or calling out when on a multi-use trail…just freewheel for a second when you come up on someone and they notice.

  • Greg on

    As always another well written and informative read.

  • Dave on

    Glad you're enjoying it. On the engagement speed, it's not like there's nothing there. It's just a case of fitness to application. I've come to appreciate quick engagement in mountain biking, yet for road I don't think it has any substantive benefits, and there are drawbacks. There are also hubs that are so loud that I'd really prefer not to ride with people who have them.



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