Friday 1/11 I went circuit checking in a 6 hour downpour. Everything got soaked very thoroughly, including the bar tape. Wind on the film to 11/11 when I converted this bike to 650B wheels which meant a change of brakes (we are talking very old school calipers). The rear brake didn't want to work properly, brake cable seized. Stripping the accessible bits and lubing traced the problem to the bars and the lever (which is an old school brake lever aero style with cables under the bar tape? None of this STI stuff!.
Well the brake works but a bit half-heartedly. Oh pxxxx. Only thing to do is going to be unwrap the bars and clean/replace the cable as necessary. Oh the joys of hidden cabling.
There are those who would say with discs this sort of thing doesn't happen. Not an option on this frame but if I had discs they would probably be cable so that changes nothing. Perhaps this is a good argument for road hydraulics but until manufacturers are offering the levers without STI (or equivalent) I am not interested. Can't use STI, causes too much pain in my arthritic thumb!
Does anyone have any experience of water seeping through cable outer under bartape? Or does it only come through the lever (in which the cable nipple faces forwards)? PITA having to retape the bars just as a result of riding in the rain (big argument for having old school flappy cables).
Can't help with the cable seepage problem, though perhaps it implies a crack in the housing somewhere under the bar tape? But interesting – in a bad way – that STI causes you pain in your thumb. Are you thinking of the old type where you had a thumb lever on the inside of the hoods for changing up (or was it down?) or is this a consequence of having your hands on the hoods more? Or something else?
I don't like road levers, so didn't realise they suffered this problem. Water getting into the cables is a standard problem on USS recumbents, where you typically have MTB brake levers (and various flavours of shifters) mounted vertically with the cable exiting downwards. I've found that covering the cable-fitting slot in the front of the lever with tape greatly reduces the amount of water that gets in (as does covering the bars with something if leaving the bike out in the rain).
I can't imagine water seeping through the side of a cable outer, unless it's damaged. Which I'd expect to happen on an exposed loop of cable that can snag on things, not the bit that's safely taped to the bars. If it gets in somewhere it will propagate along the whole cable though, and it's not always obvious when an outer has been damaged.
If your levers are particularly prone to this, you could perhaps fit an oiler port (or suitable in-line cable adjuster) to facilitate squirting GT85 or similar through the cable to drive out the water. I've found this extends the useful life somewhat, but (particularly for gears) is no substitute for a fresh cable.
The other thought is to use that stuff that Shimano supply with bar-end shifters to provide a channel under the bar tape, in the hope that it will allow you to pull through some fresh outers without disturbing the tape. (It works for me with foam grips
[1], but my bars are nearly straight, not sure how it would handle a 90 degree bend.) I've no idea what it's called, but it's the white stuff in this picture:
[1] When the grip outlives the cable.