[BillWright]

Would it be structurally unsafe to drill holes in the frame to run wires? I put a bolt on hardtail on my Ironhead and was thinking of winning wires through the frame one hole in, one hole out for the brake light and up into a diy sissy bar to turn signals.

 

[richbob]

It’s pretty normal procedure for some

 

[joe49]

Ditto, done all the time. I would do a sealant at the holes to keep water out. That isn't a concern if the tube has a opening at the lowest point that allows any water to drain.

 

[VonWegener]

Now any engineering handbook will tell you that the structural integrity of a tube is vastly reduced by drilling a hole in it but in reality bike builders have been drilling holes for tank mounts and holes for wiring purposes forever. As Joe said sealing the hole is a good idea and it is really important that the hole is deburred on the inside and chamferred on the outside to avoid the wiring chafing and shortening out.

 

[Jim Kelly]

Obviously depends on how big the hole and where it is.