It has come to light recently that there is a fatigue life problem with the large and XL size RocketMAX introduced in November 2018. As a result, Cotic is issuing a recall on all large and XL RocketMAX frames produced since the start of the production run. The safety of our owners is of utmost important to us, and therefore we had to issue the recall.

We have now had 3 fatigue failures of high mileage frames where the rider as done nothing but ride their bike a lot. No massive jumps, nothing ridiculous, these frames have just been ridden a lot, and have failed at the seat tube/BB weld. This is where the lab test frames fail at very high cycles on the fatigue test, having well exceeded the legal and our company requirements. Whilst three might not seem many in the context of a production run, these are the kind of failures that should only happen years and years into the life of a bike, if at all. For this many to have manifested in a matter of months means something is not right, and therefore we had to act.

The frame design (in XL size) went through the entire suit of ISO4210 tests (you might know them better at CEN tests, the name when it was a European, rather than International Standard), through other tests I devised which go well above and beyond ISO testing, and then went back on the rig with the horizontal ISO load case and did nearly the entire test again before failing – therefore demonstrating nearly double the fatigue life of the legal requirements. This same tubeset has been in production for 18 months on the Rocket with just a single failure in several hundred frames sold. The same down tube has been in use throughout the droplink range since it's re-introduction in 2015. The frames went into production based on these facts backed up with years of ride testing prototypes using a similar tubeset.

My conclusion is that these frames, in large and XL sizes, are longer than anything else we have yet produced using this tubeset. Despite exceeding all requirements both I and the law have for them, the down tube bending due to shock loading in regular riding conditions experienced by these fast, radical bikes, is slightly overstressing the BB/seat tube weld and reducing the fatigue life. We have had no similar issue on small and medium frames, and these have tubes sizes and lengths within the spectrum of other bikes in the range with good service records, with fatigue stresses below that of the larger frames, so they are not subject to recall.

If you have a small or medium RocketMAX from the current model year, or any 1st generation frame (green or fast red from 2016-18) these are completely fine, and sales of current model year frames continue on these sizes unaffected by the Recall and Repair.

To fix the situation, we are adding two small gusset plates either side of this joint, which stress analysis shows reduces the stress in the weld by 20%. Because of the way fatigue life works, just a small reduction in stress massively increases the fatigue life. To give you a feel for this, a 20% reduction in stress in the XL RocketMAX down tube brings the stress down to roughly the same as experienced by the medium sized original Rocket 275, which experienced no failures of this nature at all to my knowledge.

This isn't a recall and replace. This is a wasteful practice – which the bike industry is very guilty of perpetrating. It is highly likely the large and XL frames haven't cracked, but we don't want to wait for this to happen and end up with a scrap frame, and potentially riders hurt. We want to fix this. Because we are working with Five Land on this, we are doing a Recall and Repair. No scrapping of otherwise perfectly good frames. No needless use of the worlds resources. One of the joys of using steel, and manufacturing in the UK.

If you are interested in a large or XL RocketMAX, we will be back in full production at the end of September

If you have any questions regarding this issue, email me personally on cy@cotic.co.uk

Cy Turner

Founder and Director

Cotic Bikes