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My frame has quite a few holes where water gets in; 2 either side of the head tube, 1 on the downtube, and 1 on each chainstay. Only 2 holes are in use. No plugs, just plastic inserts with holes for cables/hoses.
The drain hole under the BB is tiny, and being a carbon frame with threaded insert, there is not enough space for any water to escape.
I've thought about plugging the holes with silicone or tape but fear water will still get in somehow. Maybe at the seatpost. Ideally the drain hole needs to be made larger but don't want to damage the frame.
What have other people done?
Take the seatpost out.
If I've fallen off while cycling across a ford or something, else I don't bother.
On steel and aluminium frames I've drilled out the BB drain to a bigger diameter.
No idea about carbonz....
I just ride it.
Your massively over thinking this IMHO, unless you regularly take it down the local waterslide.
But regardless, blocking up the BB drain is a terrible idea!
The drain hole under the BB is tiny, and being a carbon frame with threaded insert, there is not enough space for any water to escape.
As in the hole is so small that surface tension retains the water? That would have to be pretty tiny.
It is only a drain hole, at the lowest point of the bike, the water will drain over time unless they've built lots of little baffles and corners in to retain it
There's no harm fitting plugs to any redundant holes further up the frame to reduce water ingress but you'll never fully prevent it, just keep the drain hole clear and occasionally take the bike apart to see what the internal state of things is.
My old (carbon) Road bike used to be the worst for filling with water during winter, constant spray from road/tyres, not very good guards, various internal routing ports, and the under BB hole was used to hold a cable guide in (so no drainage), I did once empty a huge volume of water out after a very wet ride, stuck it back together and carried on riding it, it's still usable today but hung up awaiting some sort of new purpose...
Has anyone tried silicone sealant to seal cable/hose holes? I wouldn't seal the drain on the BB. I have a small tube of black silicone gasket sealant.
Has anyone tried silicone sealant to seal cable/hose holes? I wouldn't seal the drain on the BB. I have a small tube of black silicone gasket sealant.
I used a small dollop of grease a few years ago when I built my bike. It's mostly still there
Edit: Mis-read that. It's the unused bolt holes on the stays etc I greased
My enduro had a screw for the bashguard that screwed into the bb drain hole. I took the screw out and used a cable tie to hold the bashguard in place.
Before that everything in the baguette holder was getting soaked.
My carbon bikes have internal cabling and guides at the BB. When I converted the propel to wireless shifting I removed all the cabling and guides. This left a huge hole at the BB. I dont think a bigger hole than you have would be an issue. Get drilling. And before you say “remove the seatpost!” Both of my best Giants have ISP so nothing to remove.
I always put a bit of black silicone sealant into the redundant holes; sometimes around where the cables enter the frame too (whatever the frame material). It's easily removed later if needed.
As above, leave the drain hole at the bb open.
I drill bigger holes at the low point of the BB if necessary, only way to be sure that however water gets in, it gets out again. Carbon, alloy, steel whatever.
