We recently launched our new SUPA-X concept for BMX racing. This oversize design is based on the 31.8mm clamping diameter that has become popular in recent years. Taking what we have seen in the market already, we wanted to push the stiffness and efficiency boundary even further.

Our initial concept for the SUPA-X handlebar was the widening of the 31.8mm clamp area – this not only increases stiffness of the handlebar but also allowed us to consider the development of our own 31.8mm stem to take advantage of this additional width.

After months of testing and development we introduced the matching SUPA-X stem. Featuring a massive 70mm of clamping width, this stem is currently only compatible with our SUPA-X family of handlebars.

First stock of our stems arrived at the same time as our first SUPA-X handlebar – the Jordan Callum Signature 8″ model.

What has subsequently happened is that we have seen 2 separate cases of stem failure. Unfortunately both stem failures occurred with a unique series of events – the exact details of which we were not able to obtain – 1 was transported by an airline ( went missing for a few days ) and was re-assembled, the 2nd one was passed to a non-stockist workshop for a bike service. Regardless, 2 stem failures are 2 too many!

Following a series of in-house tests as well as various assembly procedures, both correct assembly and incorrect assembly , we were able to replicate a stem failure!

At this point we need to clarify that both the handlebar and stem had met and exceeded the EN Testing Standard Category 2 ( for riders over 45kg ) prior to us delivering our first product.  All FARR and FARR-ST products meet or exceed industry standards prior to reaching the market. Our internal tests had also shown our bar/stem combo to offer unrivalled stiffness and efficiency!

So how do we test? We follow the ISO 4210 Industry Standard – this is a 2-Phase fatigue test that requires 100,000 cycles per phase.

ISO 4210 Testing Standard – 2 Phase Test with 100,000 cycles per phase.

Please note the above test was done with the CORRECT ASSEMBLY procedure followed.

The SUPA-X stem uses a ZERO GAP design ( also known as Moto-Style ) which offers increased contact area for the handlebar/stem interface. You can find our assembly instructions HERE. These instructions were available at the time of us releasing the stem.

So back to the original reason for this blog post … we wanted to show why we believe the 2 stems failed and show the data that was created to mimic a similar failure of our stem.

With the stem having passed the EN 4210 Fatigue Test as per the video above, we had to try and mimic a case of incorrect assembly of the stem. For this 2nd round of the ISO 4210 Fatigue Test we did not follow the correct assembly procedure ( there was NO ZERO GAP at the Rear Bolts ) and we even tightened the Front Bolts ( 3 and 4 ) to 15NM. The stem once again passed the fatigue test.

Onto round 3 … an even more extreme version of incorrect assembly.

This is an example of incorrect assembly and what was used for Round 3 testing. The front gap is almost non-existent ( 1.68mm ) and this shows that the stem has been incorrectly assembled and/or completely over tightened ( in this case we had the front bolts at 20NM torque – effectively 2x the recommended torque specification for the bolts ). With correct assembly and following the correct bolt sequence, the front bolts ( 3 and 4 ) should have a gap of 3~4mm on average.

With this incorrect assembly and over-tightened front bolts we were able to get the stem to fail – see the video below.

 

From the above result and testing, we were able to replicate a stem failure. This result also leads us to further believe that both stems failed due to incorrect assembly and/or excessive torque settings of the front bolts.

Following this data and information we have made the decision to update all stems with ASSEMBLY INSTRUCTIONS laser-etched into each stem body. We have contacted each customer who has purchased a stem and arranged return of the stem. They will be receiving the updated version ASAP.

Further to the assembly instructions and torque details being added, we will also be adding a clear FRONT logo to the front of the stem cap. This is being done due to us seeing some stem caps incorrectly assembled back-to-front. Whilst we cannot be sure that this was done to the stems that failed, we know that it will damage the stem body as well as not allow correct ZERO GAP tightening of the rear bolts.

This has been an unfortunate series of events as it contradicts everything about why we designed this WIDER OVERSIZE STEM, we do however still firmly believe there are substantial benefits to be gained in terms of front-end stiffness and efficiency when using our SUPA-X BAR/STEM combination.

We can’t wait to see riders enjoying this exciting and revolutionary product on their bikes and racing with it on BMX tracks all around world!

Regards,

Victor

 

 

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