
Tech talk
Getting Inside The Digit Datum
Getting Inside The Digit Shock
Tim Lane’s Digit Datum, previewed here, is a reductive design that aims for modern suspension kinematic performance with fewer moving parts. It features a strut/shock absorber integrated into the top tube. This is either a bug or a feature, so to speak, depending on your personal feelings about non-universal componentry and potential design redundancy. This piece is not an attempt to reinforce or dispel one set of beliefs or another, but it is an up close look at the individual parts that make up this suspension.
Normally, by now, a month or two into taking delivery of a test bike, I’d have ridden the thing enough to have either broken something or at least find something to really love or hate about it. Instead, I got about three rides in back in November on an initial well-used, pre-production tester, then swapped that out for a new production frame, then swapped with Tim for his personal bike because I liked his Lyrik better than the Mezzer on my test bike (sorry Andrew). We went for a ride together to decide that we were headed in the right direction, and then I got one more ride on it, and then California just got shellacked by mother nature while I went to Mexico. Soooo, we are a long way behind schedule for the riding of this thing.
I did, however, manage to snap a few pics back right before the weather went berserk. This was right as I took delivery of bike number two. I was focusing (poorly) on the shock and linkage parts while Tim was spinning wrenches on the bikes. So, here’s a slightly random not-really teardown of the Digit Datum, in mostly picture and caption form.

Okay, THESE photos were taken in front of my barn this afternoon. Everything else was shot down in Tim's garage in Irvine, California back in late November. Aaanyway, if you want to remove the Digit Integer strut, you start here, by removing the two 2-mm hex screws that hold the head badge in place. You'll also have to drop the fork, so there are at least two, probably three more hex bolts that need to come out, and you may want a Voile strap or something to hold the forks and wheel rather than unbolting all that jive. The strut comes out here. I should also mention that I'm going to interchange "strut" and "shock" randomly throughout this. For the purposes of this, semantics of whether something is structural or not aside, they mean the same thing - air pressurized, oil damped, telescoping shock absorption unit - but sometimes one or the other sounds better in context.

Then you're gonna need to remove the compression damping adjustment lever (3mm), and the valve core then the valve stem itself (2.5mm). Don't forget to depressurize the strut before turning a valve core into a needle dart.

Then you must resist the urge to unbolt the shock from the rear triangle. Instead, you'll grab the handy dandy little hardware store rubber strap wrench that you knew you needed for this (that basically looks like a cross between a really beefy Voile strap and an oil filter wrench), and unscrew the stanchion from the head of the shock, leaving it happily bolted to the frame. Finally, grab that old Shimano external cup bottom bracket wrench that you've had for the past 20 years, unthread the cup holding the strut into the frame, and push the thing out through the head tube.

Here's the tool breakdown per the Digit website. It's shy of a couple hex keys, and yes, the process is more complex than taking two bolts out of a single pivot something or other, but it sure isn't rocket surgery.

Behold, the Digit Integer! If you've just removed this from the frame, the silver hammerhead at the top would still be attached to the rear triangle. As would the actual frame parts that are gripping it in this photo; they'd be welded into the rear triangle, then that black bolt would be the axle at the head of the shock. Wait, what? That's a mock-up in that photo. I know, there goes my career as a step-by-step photo tutorial guy.

There's 75mm of bushing overlap inside here, supporting a 30mm diameter stanchion. Note the bevel on the strut body at the left end of the calipers, the strut gets sucked up against a counter-bevel in the frame when the bottom bracket cup gets cranked down against its corresponding beveled surface, and this is what integrates the Integer into the Datum, so to speak. Also note, I'm piss poor at staging these photos judging by the reading on the calipers. But then again, I never noticed that Tim had his name printed on a little decal on his calipers before. Awww.

This is why nobody pays me to take photos. I'm not very good at it. Here we see one of the bushings mostly in focus, and a neighborhood parking lot in suburban Irvine that is not in focus at all. I must have been trying to make some illustrative point here, but I am damned if I know what it was.
Then you do something like that, only in reverse...

And you end up with something like this. A relatively easily accessible, simple to work on shock absorber. There are some structural benefits to using the shock as a strut; it allows for a high load integrity that doesn't suffer as much torsional or side-loading forces as some other designs. The design negates the need for an upper link, which reduces the number of bearings and axles in play. And the size of the strut itself means that it carries about six times as much oil as a regular single can air shock. This means lower operating temps, less contamination, longer oil lifespan, and ultimately less internal wear and tear.

Now let's take a look at the bottom half of this thing. Here's a shot of a bottom bracket assembly complete with 30mm spindle, lower link, and the machined aluminum swingarm mount attempting to make a break for it before the TIG welder seals their fates.

And here are their eviscerated remains. Jesus wept, my camera has a brain the size of a planet and I still managed to get the focus wrong just about everywhere here. Anyway, double row Enduro bearings for the bottom bracket itself, with the BB spindle being the shared axle between bottom bracket and linkage, and double row bearings for the linkage. So, technically, this isn't a reduction in the number of bearings, but there is one less pivot axle in play, and doubling up bearings in this area is just good policy. Also, the use of an absolutely massive bottom bracket spindle as the main pivot axle connecting the rear triangle to the frame is about as bomber-rigid a connection as it gets.

Shown here is the sleeved BB axle option that allows use of 24mm bottom brackets such as Shimano, SRAM GXP and FSA 24. The 30mm spindle is compatible with RaceFace, FSA 30, Cannondale, Ignite, 5Dev and Garbaruk, but NOT with Hope, E13, Cane Creek or White Industries (they use proprietary tapers).
That, more or less, is what goes on inside the Digit Datum. It's a pretty cool exercise in component integration and mass reduction, without any glaring weaknesses that make the danger/fear parts of my lizard brain light up. My areas of concern are less about the shock/strut, and more based around whether or not the bottom bracket will start to creak. But that is total conjecture on my part. The rain has stopped, and the next month is going to be prime riding here. We shall see how this goes.
Comments
bishopsmike
11 months, 3 weeks ago
10/10 would definitely ride. Slight concern about future serviceability of the shock, but I would probably purchase a few additional parts with the bike, and call that safe for a decade or so.
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
A few people have bought complete spare shocks with their Datums.
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Perry Schebel
11 months, 3 weeks ago
yep, i still think these bikes are neat.
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Todd Hellinga
11 months, 3 weeks ago
agreed, would love to demo one! My brother lives in the Irvine area, maybe need to go visit and pay Tim a visit! haha
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
I'll likely start doing some demo rides in spring.
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kfowler100
11 months, 3 weeks ago
Mike, thanks for reviewing this bike. It is on the top of my short list for my next bike, and your helping me make that decision! I am super stoked you joined the NSMB team! Keep the posts coming.
Tim, its super rad that your proactive in the comment threads. I want to see more of your bikes!
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Lu Kz
11 months, 3 weeks ago
I can't quite put my finger on why that completely blank piece of black material just might be the best head badge ever, intentional or not. Is a logo supposed to go there eventually? I hope not.
A datum to traditional marketing efforts!
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Lu Kz
11 months, 3 weeks ago
Actually, I didn't intend to highjack this post for self-advocacy reasons, but I think the headtube logo I modelled after my cat might be in the running...
The badge
The model
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
I figure if a tiny red tag is enough branding for Levis, a simple sticker on the top tube is plenty for me. To me, too many bikes look like they just crashed into a dumpster full of stickers.
That blank black material is 3D printed and Cerakote'd for durability.
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Velocipedestrian
11 months, 3 weeks ago
Your badge gives me Totoro vibes.
(edited to add badge image).
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Lu Kz
11 months, 3 weeks ago
That's good, the rider for that one is a big My Neighbour Totoro fan.
Me: What names/logos do you want on the bike
Her: None.
Me: Ok, but it doesn't give me a lot of room to break up the colour since we're just doing a simple fade.
Her: How about the cat?
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Perry Schebel
11 months, 3 weeks ago
now that i'm seeing it as an anti-logo headbadge rather than an access port cover, i love it.
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Kos
11 months, 3 weeks ago
Just waiting for Tim to offer a "29er corrected" rear triangle for the Datum.......
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
I don't see the Datum ever evolving into a 29er, at least in the short term, or in sizes other than XL or above. An industry wide ban on long drop dropper posts, or riding steep terrain, or people shorter than 6'4" would certainly make me reconsider, but I don't see these in my crystal ball.
I plan on launching the shorter travel Ring this year which will have 29" wheels.
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ohio
11 months, 3 weeks ago
As someone that prefers longer chain stays than pretty much every current spec, I wish you'd reconsider. Chainstay lengths still haven't caught up proportionately to the new long front centers created by slack head angles and lengthened reaches. From my calcs and hands on experience, ~445mm is now appropriate on a medium (larges and XL should be at least 10mm and 20mm longer), and that leaves plenty of room for 29" rear wheel and a straight seat tube...
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
With "As someone that prefers [something different to] pretty much every current spec" you've self-identified as an outlier. There are so many challenges already in launching Digit Bikes, the Analog Suspension, the Integer Strut, all of it really, that introducing outlier geometry would only hamper my chances of getting this boat off the ground.
Also, perhaps most importantly, I made the bike which I most want to ride - it would be pretty weird if I hadn't done that.
I'm not saying I won't at some point make a model which more closely matches your desires, just that the Datum is the model which I want to ride.
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Tim (aka DigitBikes/DirtBaggies)
11 months, 3 weeks ago
@Ohio, I notice in another thread below you asked about a 170mm travel bike. Are you talking about the 29" rear wheeled 140 travel bike which @Kos proposed above, or your proposed 29" rear wheeled 170mm travel bike here?
Either way it'll be a few years until I get around to these, so it's a bit of an abstraction at this point.
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grimwood
11 months, 3 weeks ago
Tim, this bike is so cool on so many levels. I’ll definitely keep an eye out for your longer travel version in the future (I love over-biking). I think you nailed everything for a trail bike, including the mullet.
ohio
11 months, 2 weeks ago
First, thanks for the response and engagement. You're definitely doing it right as a small upstart and I hope folks appreciate what it means to have the builder directly involved in a forum.
Second, yup, I am an outlier but I don't expect and wouldn't ask companies to build the chainstay lengths I'm proposing*. My point in this scenario is that chainstay lengths that are still well within the mainstream will support a 29" rear, and chain stays so short they will only fit a 27.5" are actually bad for handling when coupled to modern head angles and reaches. The goal of shortest chainstays that we've been sold is hack science that was barely a benefit in the days of 69deg head angles on size small frames, and definitely isn't a benefit anymore for handling.
And I hope the enduro isn't tooooo hypothetical. Because I really will buy one if you build it.
*I actually considered starting a new brand in order to introduce this approach to geo... but bailed as I decided it was too niche and esoteric to sell with any significance. So instead it's just a rant I share with every industry pro in my network, and maybe eventually it will sink in.
Tim (aka DigitBikes/DirtBaggies)
11 months, 2 weeks ago
I hear you. And I see where the trends are going, it's just not where I wanted to go with this model. I'm not dogmatic about much in bike design, the geometry will be be different for each model based on anicipated use. 29ers will certainly have a longer rear-center than the Datum.
ohio
11 months, 3 weeks ago
Love it. Hope it sells like crazy, because when he comes out with a 170mm version I'll trade in my Spec Enduro for one.
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Hawkinsdad
11 months, 3 weeks ago
Dang, that unpainted frame and simplistic design make this steed appealing. It reminds me of my Rocky Stratos, one of my favourite bikes out of many. I'd love to swing my old legs over that thing. Thanks for the timely review Mike. I hope your state gets a reprieve from the biblical atmospheric rivers soon.
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Lynx .
11 months, 2 weeks ago
Awesome little update Mike, thanks. Tim thanks again for jumping in and participating in the forum/site. Can't wait to hear/see the geo for the short travel 29er, but personally, I'm hoping that it won't have a STA steeper than 75, a HTA slacker than 66 and clearance for at least 29x2.6" tyres on i35 rims, Large would have a 475-485 Reach and Stack of around 430mm.
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