Cotic's Rocket droplink suspension explained

David Arthur David Arthur

Last week we brought you news that Sheffield-based Cotic are finalising production plans for its brand new Rocket, a 150mm full suspension bike that replaces the Hemlock.

At the heart of the bike is a new suspension platform called droplink. We mentioned it in the first look last week but Cotic are keeping us in suspense by releasing small chunks of info at a time. They’ve just released another snippet of info so we can tell you what droplink is all about.

A brief recap: the Rocket uses a Reynolds 853 and aluminium frame with a 66.5 degree head and is suited to 140-160mm forks, there’s large 15mm pivot axles, 44mm headtube, 31.6mm seat tube, ISCG05 mounts and bolt-thru rear end. A fundamental goal of the new frame was to make it both lighter and stiffer, which has lead to this design solution.

Droplink is essentially a linkage driven single pivot, with the rear shock mounted directly to the seat stays. The drop link is affixed to the seat stays just behind the shock at the seat tube, and is there to control the leverage ratio as well as increasing stiffness.

Cotic reckons the suspension is very similar to the previous Hemlock, but with a more progressive suspension performance. The large pivot axles and simple design, along with that huge seat tube give a substantial stiffness increase over the Hemlock. Another benefit cited is a more stable braking performance and better long-term durability, as the loads going through the suspension components are lower than the previous bike.

In Cy Turner’s own words, it sounds good: “It gives a fantastically fun feel to the bike which completely belies it’s 150mm of travel. It’s interactive, predictable, has that ‘pop’ to get you up and over things rather than ploughing through and gives much more support in the mid-stroke so the bike feels poised and ready for action.”

Here’s eight areas where the new Rocket is improved:

1. The suspension performance is almost identical to the Hemlock, with just a little more chain growth and pedal feedback in the small chainring.

2. It’s incredibly stiff. When combined with the steel seat tube it’s easily a match for the stiffest bikes available now.

3. The frame rate curve is what I improved. The small link gives a really nice controlled progression.

4. The tyre clearance is huge because there’s no need for a brace on the seatstay between the tyre and the seat tube.

5.  It has stable braking performance. The forward brake mount and integral seatstay pivot/brake bolt point the forces in a helpful direction.

6.  The weight is low compared to a rocker link design.

7.  The seat tube is straight with full saddle drop potential.

8.  It looks great. The seatstay lines work nicely with the top tube, and the little droplink itself tucked behind and under the seatstay means it is very neat

In fact, you can read more of Cy’s thoughts on the new bike in his quite detailed and expansive tech feature here > www.cotic.co.uk/geek/droplink

Excitingly, Cotic lets on that it is working on more full suspension bikes using the droplink layout. Good things to look forward to then. Read our first look of the Rocket here.

Let’s have your thoughts in the comments box below.

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