Tech Talk: Boost 148 explained

It's wider and stiffer, but is it necessary?

Components Tech
Boost 148 moves the rear hub flanges 3mm outboard on each side in order to improve the spoke bracing angle and increase wheel stiffness.

Boost 148 moves the rear hub flanges 3mm outboard on each side in order to improve the spoke bracing angle and increase wheel stiffness (click to enlarge).

Editors Note: This article was written by Art’s Cyclery web content editor Brett Murphy, who uses his mechanical engineering background to explain the latest industry advances and breakdown component design. The original post can be found here.

By now you have heard about the new Boost 148 hub standards. But what exactly are they and what do they mean to you?

I previously wrote an article that discussed axle standards. You can see that there are a dozens of different standards, but when discussing the latest Boost 148 and Boost 110 hubs it is more important to just look at a couple of the older mountain bike standards.

In the beginning mountain bikes generally had quick releases with 100mm spacing in the front and 135mm spacing in the rear. Within the last 10 years, QR’s have given way to the thru axle. The thru axle offers a much stiffer and more secure platform for bigger hits and harder cornering. On most mountain bikes, we now see 15mm or 20mm thru axles in the front and 12mm thru axles in the rear.

With the increasing popularity of thru axles, we saw the introduction of the 142x12mm hub and axle standard. These new 142mm hubs replaced the 135mm standard that had been around for years. But there is one important thing to remember about this standard: The distance between the two dropouts on the frame is still 135 millimeters, with an extra 3.5 millimeters of inset on each side built into the frame dropout. This 3.5 millimeters is used to guide the hub into the frame and self-center the wheel, making thru axle installation easier.

By moving the chainring outwards, you open up the frame, allowing for better tire clearance and shorter chainstays.

By moving the chainring outwards, you open up the frame, allowing for better tire clearance and shorter chainstays (click to enlarge).

Most hub manufactures offer replaceable hub end caps to convert their hubs between 135mm and 142×12. So while frame designs changed, the hubs for these two standards still have the same spoke flange spacing and other dimensions.

Now that we have some background on hub spacing, lets talk about wheel size. Originally everything was designed and engineered in the mountain industry around 26” mountain bike wheels. However, we now have 27.5” and 29” wheels, but the hubs are still the same width. With larger diameter hoops, spokes become longer. These longer spokes mounted in the same width hub create smaller spoke bracing angles.

Companies are starting to release product that will interface with the new hub standard.

Companies are starting to release product that will interface with the new hub standard (click to enlarge).

The spoke bracing angle is the angle formed between the spoke and the vertical plane. Larger spoke angles are able to balance a larger component of the lateral forces exerted in the horizontal plane during loading. So the end result is that 27.5” and 29” wheels are weaker than 26” wheels with current hub standards.

Enter Boost 148 and Boost 110. These two hubs move hub flanges outward. By moving the hub flanges outwards, spoke angles increase, creating a more stable base. So Boost standards maintain the ratio of spoke length to bracing angle seen in 26” wheels resulting in, “26” stiffness from a 29” wheel.”

Continue to page 2 to learn more about the benefits of Boost 148 and 110 »
About the author: Arts Cyclery

This article was originally published on the Art's Cyclery Blog. Art's Cyclery is dedicated to offering free expert advice, how-to videos, and in-depth product reviews on ArtsCyclery.com to help riders make an educated decision when selecting cycling gear.


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  • tyrebyter says:

    Excellent write-up. Never got the 12×142 thing. It seemed silly to move the clamping flange out to make aligning the holes easier while leaving the spoke flange the same. Actually increased the bending moment on the axle. Now there may be a reason to move on from my 10×135 through axle.

  • tyrebyter says:

    What’s with all the whining? Mountain biking is where innovation lives. Roadies are still dragging rubber brakes on rims. Boost (stupid name) doesn’t make your bike obsolete; it gives you choices. When Boost was introduced, my bike rode just like it did the day before… and who is scrapping forks because some threads are stripped? Heli-Coils have been around half a century.

  • bryan says:

    I’m happy with new innovation as long as there are real benefits. Without improved standards we would all still be riding quick releases and rim brakes like roadies. Granted on that end of the spectrum of bikes some “old” standards still make sense, but if there ever was a group of cyclists afraid of change, that would be them, and IMO roadie stuff is massively overpriced. In the mtb world new and better standards have made it possible to ride previously unforgiving terrain and stunts without breaking something every time you land, and keeping your teeth intact.

  • Yo bigger riders says:

    I absolutely feel the difference between my little and big wheels in the rear only. Both my current bikes have 35 mm carbon rims with DT hubs. , when seated and cornering or roosting hard, I totally feel this in the wobble in the 29 rear end only, but I figured a much cheaper way around this and it totally merits and revitalizes my memories of the stiffness of my skinny rimmed e 13 29er wheels that I have sitting as back up. I’m taking the rear hub and building up a fatty rear wheel this week, at a fraction of the cost of replacing my pricey 12×142 carbon frame I recently acquired! Do your homework. E 13 wheels w the skinny rims on my old bike were noticeably stiffer with the taller flanges. Spoke length is shortened more than bummer 148 crap. Its a market ploy and if you just rebuild your fatty35mm rear rim with new short spokes and an e13 rear hub you will smoke this new market bs standard!!!! Haahajjhahahahahahhahajajaj

    • Mr. P says:

      Yo bigger riders, check your “taller flanges” *marketing* facts. In a 2x or 3x build, flange height makes very little difference in lateral stiffness. Flange height makes a big difference for radial builds only. Look at your MTB hub on your wheel, the flange height does not shorten the spoke, just moves it more away from the axle.

      P

  • Yo bigger riders says:

    Uhh read above. Its not necessary. Please read prev. Comment and save money and donate to poor children instead please…….

  • Yo bigger riders says:

    No stupid diagrams necessary, just real !world experience for you all. At least for xc riders that are ~ or > 200 lbs.

    Read above comments. No profits intended.

  • Yo bigger riders says:

    That’s MTB innovation for you. Like in the old days. Thanks e 13 and Mr gravy!!!!!

  • Yo bigger riders says:

    The additional noise from their hubs, is well worth it and keeps the cougars and bears at bay when ripping in the BC!!!!!!!!!!!!!

  • turbodog says:

    Whomever came up with this needs to launch themselves off a drop. Preferably a very large one. With a fire at the bottom.

    I think this standard will finally mark a turning point in the bike industry. Between this and “27.5!!!!!1!!” there will hopefully be several major bike companies going out of business from extremely poor sales of these completely foolish new standards. Don’t feel obligated to waste your money on them, nobody is making you. Spend your money on real products.

  • Fernleigh says:

    “Stiffer 29er Hoops – Brillant”..

  • Lew says:

    Of course now they’ll have 110mm x 15mm. But someone will do some testing in Maybe a year or two’s time, or someone will just think about it in some place then they discover actually 20mm x 125mm is just much better and more rigid for riding especially with 29ers.

    This in a nutshell is why I’m starting to despise the cycle industry.

  • djon101 says:

    All the expense of new components for the sake of 6mm !!

    2 years time they will say” that’s not enough -you need ‘BOOST 160′ ”
    The Industry is taking the #### out of us just to guarantee future profits !!

    I jumped on the 27.5 bandwagon, sold all my trick 26″ stuff. I sure ain’t continuing with this uneccesary crap

    • enio jurko says:

      So you bought into the 27.5 hype(stuff is almost the same as 26, placebo pill), and you dismiss boost? Hahahahaha. Well you placed a bet and lost, deal with it!

      • Lloyd says:

        Yeah, so people who bought bikes in the past 4 years should’ve stuck to the huge influx of 26″ wheeled bikes that were showing up in bike shops instead of placing their bet on that lone 27.5 in the corner. ..or maybe the reality is that no matter what you do, there’s a retro-bike-troll on the web ready to heckle everyone who’s bike is not exactly like his.

  • jiw71 says:

    never thought I’d see the day when I would drop almost 4 grand on an aluminum hardtail. But once I did the research and understood the advantages of Boost 148 & Boost 110 (as well as 29+ wheels) for my riding style, I sprung for a Trek Stache 9. By far the best bike I have purchased!

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