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Aero Lever Brake Splitter Installation

Typical Tools and Supplies Needed.

  • Park Tool BT-2 "forth hand"
  • Park Tool Cable Cutter CN-10
  • Park Tool SD-6 straight blade screwdriver
  • Scissors or knife such as UK-1
  • Hex wrench set AWS-3
  • Handlebar Holder HBH-2

This article will discuss the installation of brake cable splitters for double control brake levers on racing bicycles. A cable splitter allows one brake caliper to be operated by two different levers. For example, an alternate lever can be added to the end of the aero-bar extension (Figure 1). This allows the rider to maintain a full aerodynamic position and use the brake to scrub speed before corners. The outboard lever may also be used as an option. Always check with the manufacturer for specifications. An example of a manufacturer of these is Jtech, at jtekengineering.com/

Figure 1. Alternate brake lever at aero bar extension with outboard lever option.

The model lever described here in intened to be installed with bar end shifters. Begin by removing handlebar tape from the aero bar extension. Remove the shift lever bolt and sleeve nut (Figure 2).

Figure 2. Remove screw and sleeve nut. Sleeve nut will not be reused for the model shown here.


The alternate brake lever shown here has the sleeve nut build in lever body (Figure 3).

Figure 3. Install lever and secure with lever screw.


Alternate lever mounts inboard of lever. Re-install screw and tighten (Figure 4).

Figure 4. Installed alternate brake lever.

The model of splitter described here requires three pieces of housing and two cables (Figure 5). The primary cable runs from the alternate aero bar lever through the splitter mechanism and back to the rear brake. One piece of housing will connect the aero bar lever to the splitter. A second piece of housing will connect the splitter back to the brake caliper. A second cable and the third piece of housing will connect the splitter to the outboard lever at the handlebar (Figure 6).

Figure 5. Splitter with housing pieces.

Figure 6. Rear brake housing is highlighted here with blue dotted lines.

Size and cut outboard brake lever housing to length. Housing will curve but should not be kinked or severly bent. Feed the brake cable from the outboard lever to the splitter. Use housing end caps where ever they will fit. Use BT-2 and pull slack from cable. Secure splitter setscrew to hold cable (Figure 7). Cut cable and install end cap.

Figure 7. Secure splitter setscrew.

Size and cut alternate aero bar housing piece. Feed primary wire through brake lever, housing, and through splitter (Figure 8).

Figure 8. Feed primary wire from aero lever through splitter.

Determine splitter-to-frame housing length. Rotate bars to opposite direction of frame housing stop and cut housing to only allow rotation to 90 degrees (Figure 9).

Figure 9. Rotate bars and determine housing length accordingly.

Feed cable through last piece of housing and back to caliper. Attach cable at caliper and pull slack from cable. Secure cable pinch bolt. Test both brake levers by pulling firmly. Wiggle outward brake lever (Figure 10). If there is much travel before lever pulls cable, use barrel adjuster in cable splitter to remove slack.

Figure 10. Test lever for movement.

Inspect splitter at rest and during full load with each lever (Figure 11). Splitter has limited travel and should not close shut before limit is reached (Figure 12).

Figure 11. Splitter at rest showing full extension of linkage.

Figure 12. Lever pulled fully with splitter working properly.

If the splitter shuts fully when the lever is pulled it will no longer transmit cable pull to the caliper (Figure 13). Remove slack from system.

Figure 13. SAFETY NOTE: Splitter is closed and will no longer allow cable pull to the caliper. Remove cable slack and test again.

Aero bar extension is are ready for tape. Allow housing to enter the lever in a straight line (Figure 14). Do not tape housing directly against bar as this will bend housing as it enters lever housing stop.

Figure 14. Alternate lever at aero bar end with bar tape in place.