Bicycle Mechanics - Keeping water out of the frame

Well my Trek 5200 arrived and after assembling it, I realize how many entry points there are for water. The drill outs for the water bottle cages, the bracket that holds the handle bars. Holes where the cable comes out of the frame.

For a carbon frame does it matter?

For a carbon frame does it matter?

The carbon won't be effected but you have other parts to worry about like the bottom bracket. Also, carbon frames typically have metal inserts in the head tube, seat tube, nutserts for the bottle cages, etc. Many times these are aluminum but sometimes they can be made of other metals. My carbon road frame actually uses steel inserts for the seat-tube and headtube (steel near the cups and aluminum in the middle) for more durability.

i'd be serprised how much water gets into a frame realy, and as the BB is the lowist point it will all meet there, i normaly cover the BB in copper grease just to stop corrosion and ofcourse do the threads

But the BB shell is solid, right? That is, if you remove the seat, and pour a cup of water down the seat tube, none of it is gonna go into the BB shell. Right? Maybe it's different on a CF frame.

But the BB shell is solid, right? That is, if you remove the seat, and pour a cup of water down the seat tube, none of it is gonna go into the BB shell. Right? Maybe it's different on a CF frame.

It depends. Some are solid and some aren't even for metal frames such as in some monocoque aluminum MTB frames for instance. Most CF frames don't have a solid shell down there but they do typically have a shell insert or sleeve in which the BB is threaded into. This is typically made of aluminum.

Wow, I was wondering about the same thing on my bike. There are holes everywhere that water could sneak into.

Since I ride in the rain a lot, I make it a point to occasionally pull the seatpost and tip the bike upside down to expunge the frame of any water from time to time.

Well my Trek 5200 arrived and after assembling it, I realize how many entry points there are for water. The drill outs for the water bottle cages, the bracket that holds the handle bars. Holes where the cable comes out of the frame.

For a carbon frame does it matter?

When I ride in the rain, I just assume that some water is going to get into the frame. I don't let it worry me very much, but I make sure to leave it a way out. On a metal frame, I'm a believer in drain holes. A tiny little hole (1/16") in the bottom of the bracket shell is all that it takes. I don't think I'd be too keen on drilling a hole in a carbon bottom bracket shell. Pulling the seatpost and hanging the bike upside down is a good idea too.

Some wheelsets (Rolf Vector Pros) are notorious for collecting water during rain rides. PITA. The only real remedy for those is to pull the tire and rim strip to let them dry out.

Since I ride in the rain a lot, I make it a point to occasionally pull the seatpost and tip the bike upside down to expunge the frame of any water from time to time.
if you can attach a bike hook at the ceiling, then you can hang your bike rear wheel hanging on the hook, after observing that there's no more water dripping then you can hang your bike front wheel first....

Since I ride in the rain a lot, I make it a point to occasionally pull the seatpost and tip the bike upside down to expunge the frame of any water from time to time.

Is the water coming in through the water bottle cage?

Is the water coming in through the water bottle cage?

Primarily it's coming in through the seat-tube. I run an Easton CT2 carbon fibre seatpost. Easton designs their carbon posts with stress relief sections. Thus the post itself is not totally round. There are flat spots on the front and back. As a result, this leaves a gap (for relieving the stress) which water can enter. Typically when riding in the rain, the water will hit my seatpost, saddle or me and run down the length of the seatpost until it enters in through the gap.

You could lawyas do as Chris Chance did and seal them off with wax.

i think this idea has come up on here before and ive heard of people doing this regularly with AL frames... Drill a small hole at the very most bottom part of the BB. that way any water in the frame will drain out.

i think this idea has come up on here before and ive heard of people doing this regularly with AL frames... Drill a small hole at the very most bottom part of the BB. that way any water in the frame will drain out.

I'm not sure it's as safe to do with carbon

I'm not sure it's as safe to do with carbon

It's not. I would strongly recommend against doing this. If you want to try then I would first contact the frame manufacturer but my guess is that they will tell you not to do it.

I'm not sure it's as safe to do with carbon

I was thinking of the drilling idea myself. Why is it not safe.

I was thinking of the drilling idea myself. Why is it not safe.

think of carbon fibre as like a piece of cloth. Well, actually the fibre mesh is a piece of cloth. Cutting the fibres can cause fraying. In the best of cases, drilling carbon fiber must be done with extreme care to avoid delamination, fraying and creation of micro-fissures.

think of carbon fibre as like a piece of cloth. Well, actually the fibre mesh is a piece of cloth. Cutting the fibres can cause fraying. In the best of cases, drilling carbon fiber must be done with extreme care to avoid delamination, fraying and creation of micro-fissures.

Well they must do something to correct the holes for water bottle cages. Hmmm. There's probably a finish treatment to prevent "fraying".

Tonight, I'm going to put a simple gasket around those cage holes to block water. And look for other entry points. Water seems to be a problem in general. Last night while installing the rear blinky, I noticed that the bracket screw that goes directly to inside of the light was unsealed. The small gasket I made should work. The light did have a gasket for the permimeter tho.

Well they most do something to correct the holes for water bottle cages. Hmmm. There's probably a finish treatment to prevent "fraying".

While some frame manufacturers will drill and tap holes for things like bottle cages, most really good carbon fibre frame manufacturers will embed nutserts into the structural fibres at the time of molding. It's the difference between throwing in the walnuts into the dough before baking versus taking the bread out of the oven when it's done and then gouging out the surface to jam bits of walnuts in after the fact. The first process produces a more reliable stronger frame.

yeah carbon fiber sucks haha jk. i would just cauck(did i spell that right?... it looks wierd) or plumbers tape for the water bottle mounts and any other small holes you can seal.

just drill more holes for drainage....it will lighten it up AND make you go faster!

END NOTE: Do not do the previously stated....

My experience is that, during heavy rain water will find a way
in no matter what. So, the some other posters have said, it's
more a case of finding ways it can get out rather that going nuts
trying to stop it getting in.

Having said that, I dont have a carbon bike.

My experience is that, during heavy rain water will find a way
in no matter what. So, the some other posters have said, it's
more a case of finding ways it can get out rather that going nuts
trying to stop it getting in.

Having said that, I dont have a carbon bike.

The area that seems to NOT drain OK is back by the rear cassette and hub. I don't think hanging it from the ceiling will drain it because when I turn the bike upside-down for other maintenace, no water seeps out.