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.
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 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