Carbon shaft extension

Cut off carbon lengthen racing fork too short
Cervélo Aero carbon fork shaft extension by 40 mm

Despite all the attention, it happens again and again that you shorten the steerer tube too short and it lacks the deciding millimeters for the right handlebar position, or you take over a used frame, a complete bike, but the handlebars can not be mounted higher. 


We recommend at first always to check the new or additional purchase. Often, however, this is no longer an alternative, as the original fork is no longer available due to old models from the manufacturer. 


If all possibilities are checked, this is no reason to write off the bike. Based on our many years of experience in manufacturing, repair and modification, we can easily realize an extension of a carbon shaft.



Extension of carbon fork stems

The fork stem of a carbon fork cut too short!

Review of process and processing technology according to ISO standard 4210

Safety carbon fork - fork stem cut too short
Examination of a fork stem extension on an older Smolik Motivation Race SLX carbon fork according to ISO Norm 4210 by EFBE Prüftechnik

The procedure and processing technology of our offered fork-leg extensions of carbon forks for models no longer available on the market, we have tested successfully without complaints at the company EFBE-Prüftechnik independently, objectively and transparently according to the ISO standard 4210-6: 2015 for forks of the category racing ( RD) to the corresponding critical load cases . 


Our test specimen was an older Smolik Motivation Race SLX carbon fork, which was extended by 2 cm for test purposes. In the picture on the right you can see the shock test backwards - torsion test of the steerer tube.


Safety carbon fork shaft too short - repair carbon
Tensile test of the Smolik Motivation Race SLX carbon fork to ISO standard 4210

In another test case, see picture left, you can see the test for tensile load of a non-welded fork in accordance with ISO standard 4210 of the Smolik Motivation Race SLX carbon fork supplied by us. 


Overall, the test was successfully carried out without any complaints, and no parts of the unit relaxed or separated. In addition, there was no evidence of fatigue in the form of cracking.

Technical realization of a fork stem extension

Carbon fork cut too short Shank extension Carbon
Carbon fork shaft separating cut according to the given head tube height and desired final length

The extension does not take place by a preparation / extension in the true sense, but by the technologically correct incorporation of an intermediate piece. Here, the position is selected so that the interface is largely stress and load free at a certain position with respect to the height of the head tube, and the desired final length. 


For this reason, the specification of the head tube height is a prerequisite for the technically perfect implementation. 

carbon repair modification bike stem fork
the same fork after carried out carbon shaft extension

The maximum extension, which we offer and give warranty, are 40 mm. This limitation is based on the fact that the max. spacer height generally are 40 mm to the standard value. 


Likewise, the warranty is limited to the specified parameters, ie head tube height and protrusion / extension. The fork is therefore no longer for a different configuration than the frame dimensions and the desired height you specify universally to use, but is then tailored to your specific frame, modified.

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