Kris at 44 Bikes Explains Superboost’s Benefits for Hardtail MTB Frames Nov 10, 2017


Photos by Jarrod Bunk

135mm, 142mm, boost and now “super” boost. What gives with all these rear hub standards? I just wanna shreddd! Well, Kris from 44 Bikes knows a thing or two about shredding and frame design, so he tackled explaining superboost in his latest blog post:

“Earlier in the year, I put together a post just after completing the next iteration of the Marauder in a titanium prototype. You can read that post here. What is special about this bike is I used the pre-existing 157mm TA standard paired with an 83mm shell width. This is technically an existing DH standard which Pivot tweaked by adjusting the flange spacing of the non-drive side to move it outboard a bit more to stiffen up the rear wheel build and subsequently re-marketing it as “Superboost”. Which I think took some by surprise as a “new” standard. It’s quite the contrary. And when paired with that 83mm shell width (another existing standard) you get perfect chain line and a critical area of the bicycle is literally opened up to so many opportunities as tires gain more volume and width. ”

Keep reading at 44 Bikes!

  • Bil Thorne

    That’s the same BB as an Otso Voytek, so yeah it does open up more tire clearance.

  • Bert

    But the resultant chainline is pretty much the same, no (Superboost vs. Boost)? I understood there was only about 1mm diff.

    • Did you read the full article?

      • Bert

        Yep, mentions nothing of resultant chainline though? Pivot say 53mm vs. 56mm with same Q-factor so I guess it’s worthwhile. I thought they were much closer – my bad.

        • Set aside chain line for a moment: First consider the trend towards large volume tires and the inherent lack of tire clearance with a 73mm bottom bracket shell paired with a 12×142 or 12×148 spaced rear end. Efficiency of drivetrain is relatively smooth sailing with 73mm BB shells and paired with a 12×142 rear end. Now bump that whole assembly up to a 73 x 12×148 and often times you get a bit more chain cross over in the extremes of the cassette when you want to keep performance attributes of a hardtail optimized (to me, that’s in the 16.5″ / 419mm range). That means increased wear on the drivetrain and backpedaling issues. Boost is a halfway step to achieving all the goals I’m after: Performance, drivetrain efficiency and tire clearance. The issue is clearance between tire, chain stay and chain ring. When you bump the rear axle spacing to a 12×157 and pair it with the appropriate 83mm shell, I get performance, drivetrain efficiency and tire clearance. The fear I believe is the increase in q-factor of a 83mm shell and hence the resistance initially to jump up to 12×157 which has been rebranded as “Superboost”. In reality, to my sensibilities, my body quickly adapted to that slight gain in q-factor (aka tread) that is inherent when you pair the appropriate bottom bracket width of 83mm’s with 12×157. I get everything I’ve been after with that pre-existing standard. Hope that helps.

          • My trail bike (the only one with a suspension fork) is a 197×12 fat bike, with a 26″ fat wheelset and a 27.5″+ wheelset. I usually ride it with SPDs, but also with flats, and long ago got over the worry that my Q-factor was too high. I really enjoy riding 29″ and 27.5+ hardtails, so 157×12 will definitely be in consideration for my next bike.

            It is interesting to note the differences in Q-factor between the Turbine and Next cranks, though… would be nice if that was a measurement companies published. Crank spec seems confusing, but we don’t have to look too far back to remember determining what length of square taper spindle we’d need…

          • lyle driver

            It is nice that Race Face publishes that spec:
            https://www.raceface.com/media/Crank_Q-factors_and_chainlines.pdf
            I did a bike a couple years ago with 12×177, with a DH 149 spindle in a PF107 (aka 83mm BSA), and flipped ring. Works great. Incredible rear wheel triangulation, narrow Q and fits a 4″ tire.

          • You also hacked something with my crankset to reduce the Q, but I cannot actually recall what combination of parts it is. I do know you chamfered some sharp edges and did some custom machining to improve chainline, ’cause that’s the kind of thing you do.

          • Nice! Got any photos dude? Sounds sick!

          • Lots of photos here… they took the opportunity to bring back the classic Suzi Q name with a bike that focused on reducing fat bike Q-factor through Lyle’s experiments with bikes like my Blizzard.

            http://www.bikes.com/en/bikes/suzi-q/2018

            Pretty rad to combine DH width cranks with a fat rear end. Makes you wonder what other possibilities are out there given direct mount cranks and different chainring offsets.

          • Chris Holzner

            Have you considered using a T47 (or PF30) 91.5mm BB? Same cranks and same q-factor as a 73mm BB and LOTS more room for welding, less extreme bends in the chain stays.

            http://www.paragonmachineworks.com/frame-building-parts/bottom-bracket-shells/bb0049-titanium-t47-2-od-x-92-5-mm-wide.html

          • No PF (Press-Fit) anything on any of my bikes – Threads only on bottom brackets. T47 definitely. I’m weighing a T47 (83mm) for my next prototype in steel. Forming and bending of stays isn’t necessarily an issue with the stay material I’m using. Most pre-bent material only has so much wiggle room and I’m more of the mind to use raw material in that area so I have full control over all the bend radius’s and forming techniques at my disposal.

          • Chris Holzner

            I think there are a few details of this concept missing from this discussion. With the correct Super Boost Plus chainring, and the resultant 56mm chainline appropriate for the 12×157 rear, there are no drivetrain efficiency or backpedaling issues. Before the prevalence of 1x drivetrains, this would have much more difficult to work out and market. Also, Pivot’s intention wasn’t just to use the 12×157 spacing and call it Super Boost Plus, but to take advantage of that spacing to move the hub flanges out as much as possible, continuing what Boost started, to increase the bracing angle of the spokes, especially for 29er wheels.

            If you haven’t seen this, it does a very good job of explaining Pivot’s approach and intent:

            http://www.bicycleretailer.com/sites/default/files/downloads/article/Pivot_Super%20Boost%20Plus_INTL.pdf

          • I mention hub flange spacing in the blog post FYI (the discussion here builds on that post).

          • Chris Holzner

            Sorry :(

  • donnie

    A number of builders have been doing this for years, the 157×12 for plus bikes that is. Pivot ( I believe ) stepped up to do them on production bikes as of lately. Reynolds brought this “new” standard on to accomodate.
    Makes a lot of sense for builders to get a few more mm’s out of frames with everyone demanding the widest tires.

  • Dom.T

    Not surprised to see this new standard. Even a few years ago i saw people using 150 (qr) with 83mm BB shells for custom plus bikes. It was the standard on dh bikes for a long time. The 83mm BB is a no brannier, it is just moving the ring outboard accordingly. Moving to 157 to incorporate the 3.5mm (x2) inset for thrus makes sense. I agree with Kris that Q factor is the biggest issue and many designers (i am one) would have previously considered this as potentially too off putting for their customers. Simply giving it a name helps. I think the user will adapt to it after a couple of rides. The bottom line is it makes life easier the builder/designer and makes yokes and plates less necessary. You’ll see this on a lot more bikes.

  • breed007

    I have a hard time seeing Q factor being a huge issue on a long-ish travel hard tail. I could see being concerned with that on a XC race bike, but you’re not going to put tires that wide on a bike like that so it seems like a non-issue.

    • “I could see being concerned with that on a XC race bike, but…” <- THAT. So much of bicycle design used to be race oriented. I'm seeing more and more design being driven by "riding" and not "racing". 99.9% of my clients do not race. All of my bikes can be raced, but when you weigh terrain, riding style and "how" riders are riding their bikes, squeezing every possible watt out of every pedal stroke is not necessarily the goal. There's so many factors to weigh. Q-Factor (IMO) is one of those factors that needs to be considered when optimizing a bike for race conditions where every piece of the performance pie is paramount. And I have to be honest with myself: Riding and having fun and envisioning a mountain bike to be a big BMX bike for the woods is my goal. I want my bikes to ride the whole mountain and enable the rider to session every line in between the trailhead. End Note: I will listen to the client however if they have a physical issue that warrants a low q-factor.

  • Doug M.

    Superboost makes so much sense for contemporary MTBs. Big ups to Kris for advancing it.

  • Dom.T

    Not surprised to see this new standard. Even a few years ago i saw people using 150 (qr) with 83mm BB shells for custom plus bikes. QR versions were around on dh bikes a decade+ ago so hubs/chainsets were about. The 83mm BB is a no brannier, it is just moving the ring outboard accordingly. The move to 157 to incorporate the 3.5mm (x2) is obvious and inevitable. I agree with Kris that Q factor was/is the biggest issue and many ‘production’ designers (i am one) would have previously considered this as potentially too off putting for their customers. I think the user will adapt to it after a couple of rides. other issue was a lack of non-DH chain sets that were compatable. Simply giving the standard a name helps a lot but it is just a name. The bottom line is it makes life easier for the builder/designer and makes yokes and plates less necessary. You’ll see this on a lot more bikes.

    • What’s interesting is observing the maturing of the mountain bike market and it’s rider base. There’s been a lot of progression and evolution just within the past 5 years as tire size and wheel size have been a source of a lot of experimentation. I agree that this is the next logical step. It’s one I’ve been wanting to use for some time and planets aligned on a pair of wheels to make it happen. One thing I’d encourage everyone out there though doing the design heavy lifting is to think about what kinds of bikes YOU want to ride. The bikes I design and build are just that. I jest that this is “My bike. Your size.” It’s the bike I want to ride and that dictates all my design decisions.

      • Dom.T

        I absolutely agree in terms of designing bikes you want to ride. On high end models you can push the boat and use a standard where only a small handful of companies make the parts. As you trickle down the range then you are reliant on the standards set from the big 2 drivetrain companies to attain pricing goals etc. It is important for custom guys and also the top line products from ‘production’ guys to push the envelope and explore these standards. As per my original post just calling it ‘super boost’ helps a lot and will drive its availability.

        • Good points and thanks for sharing those insights. What’s nice about a lot of those top end component manufacturers is they’ve gone back to a true 3 piece crank set up (some had been integrating the spindle and crank arm for a time). But that’s an element of square taper that I always liked: different spindle lengths to adjust chain line and allow for more options with tire, chainring and chain stay clearances. Hopefully the big 2 you mention take that lead.

  • Michael

    I can see the benefits to builders for sure and I suppose if it’s easier for builders to build bikes people want then ultimately it also benefits consumers. However, my “ancient” Krampus has 73bb and 135qr! Fits huge tires, the chainstay is as short as I’d like it to be for a hardtail and I’m running it 1×10 with a big pie plate in the rear with zero issues…