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Bicycles

Datum MTB boasts simpler, smoother and lighter rear suspension

By Ben Coxworth
November 25, 2021
Datum MTB boasts simpler, smoother and lighter rear suspension
The Datum's Analog rear suspension has a considerably cleaner look than most traditional systems
The Datum's Analog rear suspension has a considerably cleaner look than most traditional systems
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The Datum's Analog rear suspension has a considerably cleaner look than most traditional systems
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The Datum's Analog rear suspension has a considerably cleaner look than most traditional systems
The Analog system has just three pivot points (two of which are pictured here)
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The Analog system has just three pivot points (two of which are pictured here)
The Analog rear shock is described as a strut, as it's also a structural part of the frame
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The Analog rear shock is described as a strut, as it's also a structural part of the frame
The Datum bike is currently only being offered as a frame
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The Datum bike is currently only being offered as a frame
The Datum prototype in action
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The Datum prototype in action
A cut-away view of the Analog rear shock
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A cut-away view of the Analog rear shock
View gallery - 6 images

On most full-suspension mountain bikes, the rear shock sits between the swingarm and the main triangle, with eyelet connectors at either end. The Datum bike is different and supposedly better, though, in that its rear shock slides into the frame's top tube.

Created by California-based bicycle designer Tim Lane, the aluminum-framed Datum is being manufactured through his company Digit Bikes. It was the subject of a successful Kickstarter campaign back in August, and is now on Indiegogo to raise additional production funds.

As mentioned, its big distinguishing feature is its patented Analog rear suspension, in which the front end of the air shock slides into the open rear end of the top tube. According to Lane, there are several advantages to this design.

A cut-away view of the Analog rear shock
A cut-away view of the Analog rear shock

First of all, it utilizes significantly fewer pivots (and thus fewer links, bearings and axles) than traditional rear suspension systems. This means it's approximately 200 to 600 grams lighter, provides more room on the frame for things like water bottles, incorporates fewer parts that could wear out and fail, plus its chassis is stiffer – again, this is because there are fewer suspension components to flex.

Additionally, the Datum's long, straight seat tube is able to accommodate longer seat posts than many other full-suspension mountain bikes.

And importantly, because its rear shock has pretty much the entire length of the top tube to work with, it's able to be much longer (over 12 in/305 mm) than a shock which is constrained by having pivot points at either end. This results in 140 mm of rear travel which is claimed to be much smoother and more predictable than that of conventional shorter shocks.

The Datum prototype in action
The Datum prototype in action

The Datum bike is currently being offered as a frame only, the final version of which should weigh about 7.25 lb (3.3 kg) in a size Large. A pledge of US$3,150 will get you one, assuming it reaches production. The planned retail price is $4,000.

Lane goes into more detail about the attributes of the Analog suspension system, in the following video.

DigitBikes Kickstarter Campaign Video

Source: Indiegogo

View gallery - 6 images

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BicyclesMountain BikesSuspensionIndiegogoNew Atlas Audio
8 comments
Ben Coxworth
Ben Coxworth
Based out of Edmonton, Canada, Ben Coxworth has been writing for New Atlas since 2009 and is presently Managing Editor for North America. An experienced freelance writer, he previously obtained an English BA from the University of Saskatchewan, then spent over 20 years working in various markets as a television reporter, producer and news videographer. Ben is particularly interested in scientific innovation, human-powered transportation, and the marine environment.

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8 comments
Daishi
All it really does is trade the outer cylinder of the suspension damper with an added frame support bar which is needed because they cut into the triangle. I would say the weight would be about the same but the sacrifice they make is the suspension damper is harder to work on or replace because it's integrated into the frame now. The extra travel it gains could be done just by using a longer damper that attaches farther along the top tube. I have dozens of inventions and seeing stuff like this makes me wish I had better partnerships to explore them.
Martin Hone
I would have thought some technical discussion was required, rather than just reproducing the information from the Press Release....
RedGobbo
I would like to know how the damper is replaced/assembled into the frame. The welded frame vertical piece seems to be too close to allow withdrawal/insertion of the damper.
Trylon
RedGobbo has a good point. And I'd be very leery of any proprietary shock design. Sooner or later, every shock needs to be rebuilt or even replaced.

Worse, without an upper pivot on the shock and with a rigidly fixed swingarm pivot to shock eye distance, there's no way to accommodate the significant vertical deflection throughout the 140mm (almost 6") travel, which will put a lot of stress on the shock, wearing out the seals prematurely.
Nelson Hyde Chick
How do you get to the shock if it breaks?
Gregg Eshelman
@Trylon I wondered the same until I watched the video. It uses a short link behind the bottom bracket, connecting to the lower corner of the rear frame triangle. So this design brings into play all the issues with the chain (distance between front and rear sprockets always changing) that earlier rear suspension designs had before someone figured out how to make the rear pivot concentric with the pedal axle.
ljaques
Because we made your brain hurt for a minute, trying to figure out how the arc of the piston didn't wrench the frame apart (dual pivot is key), we're charging you 10 or more times what the bike is worth. Thanks for shopping Mercenary Bykes!
@Trylon, the bottom is a dual pivot, so the rear wheel frame can move up and down, relieving (some of the) stress on the piston. I'm sure it'll still wear quite quickly.
ljaques
It's probably the smaller diameter of the interior parts of the piston which make it able to skew sideways to bypass the vertical tube. RCH territory, for sure.