Question: Other than providing a “clean” look, what is the advantage of internally routed cables? I was under the impression that putting a hole in a tube weakened it and it let in water. I also thought that standing water in a tube, no matter the material, was not a good thing.
Thanks, Larry H
Jim Langley’s Answer: That’s a great question, Larry, thanks,
When they put holes in tubes in order to run the cables inside, they reinforce the tube at the holes so that the tube is as strong as it was before and can’t fail at that point. Depending on the frame material, it’s done different ways. It won’t weaken the frame if it’s done well.
Water gets inside frames regardless of whether or not there are holes for cables. All frames have vent holes in various places designed to let the water get out. But, with steel frames, we know that water can damage the steel and eventually rust out and ruin the frame. So, a builder making a steel frame will try very hard to prevent moisture entry.
With aluminum, titanium and carbon frames, the water won’t do any damage and as long as it can drain out, it will only collect and add a little weight for a short period of time. So standing water is bad from a sloshing around and adding weight point of view but it shouldn’t harm the frame. And any components it comes in contact with should be lubricated which should prevent corrosion.
Ideally, though, the water gets out of the frame almost as fast as it gets in. This isn’t always the case. If you work on bikes you will see water at the bottom bracket a lot of times – especially on mountain bikes where they ride through creeks, etc.
I’ve even seen rims full of water. Riders often have no idea it’s in the bike.
Besides the clean look, a cable running inside the frame is protected by the frame. Outside it can be more likely to rust, fray and fail. But, internal cables have to be done right. If not, the outer cable routing will still be superior and easier to maintain, too.
Perhaps sexier, perhsps marginally more aerodynamic.
However, ask most mechanics; they’ll say it’ll inevitably cost more in labour when it’s time to change those internal cables, notably if there are no internal frame sleeves to guide those new cables, as they have to fish them around inside the frame…
Internal routing isn’t that much harder to re-cable even in the absence of internal sleeves. There is tubing specifically designed for this purpose, and you basically snip the derailleur end off the old cable, reverse-feed the sleeve/tubing along the cable until it pops out the next “port” in the frame. Use separate pieces of tubing for separate pairs of “frame ports”.
water is not going to ‘stand’ – you go up and down hills, water in the frame is going to end up at the low point, the bottom bracket and most of the time there are holes there for it to get out
I’ve been riding steel frames all my life. 4,000 to 6,000 miles per year. During the winter in the San Francisco Bay Area it rains. I ride in the rain (commute, utility, fitness/exercise, fun). I have never had any problems with rust. The frames that have failed have done so for a reasons other than rust. Alas, I have never gotten more than 75,000 miles out of a frame. I store my bike(s) inside (out of the rain) when not riding. I have never taken any special care to be sure that any water that has gotten in gets out. ~0le
I never could find any vent holes in my 1987 Marinoni made with lugged Columbus SLX steel tubes, which notably is fully chromed under the paint. I recently learned that chrome plating is a problem around small openings like small vent holes, so Mr. Marinoni probably put a dot of brazing on the vent holes before plating. There is a drain hole in the BB to release any condensation. And I’m happy to have external cables on all our bikes!
Anyone recall when they started doing this ?