We often get asked about doing internal Di2/EPS conversions to frames that were not originally designed with this in mind.

Can I just drill a few holes where I want the cables to come out?

Drilling holes in a frame is NOT recommended, be it carbon, aluminium, steel or titanium.

Performance bicycle frames have been engineered in the factory to have minimum weight for the loads placed upon them. Drilling a hole removes material needed to carry the loads and also acts a stress concentration.

A factory ready electronic shifting frame has had analysis done on the structural implications of the holes and extra material placed around the area to distribute the loads. The location of each hole and the structural design is carefully considered to ensure it is safe.

Without this analysis the frame is NOT safe to ride.

The image above is an extract from the Kenworth truck manual. As you can see they have very clear guidelines for drilling holes in the chassis. They are rightly concerned about the structural implications of drilling holes in 10mm thick steel beams.

Drilling holes in the frame will also void your factory warranty and also may have legal implications if it fails and people get hurt. Yes we are conservative, all those years working with aircraft we used to say “nobody wants a plane to fall out of the sky”. The same way I don’t want to see people get hurt while out enjoying riding their bikes.

The battery also needs to be considered, Lithium batteries without the correct protection circuit are prone to fire if incorrectly handled, you definitely do not want an internal fire in the seat tube of your carbon frame. This issue actually recently grounded the Boeing 787 fleet

We always recommend using a frame and parts designed and tested for the purpose intended.

Safe riding.