Drilling holes in a frame

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Location
Loch side.
I'm wondering about internal and external bike cables. If you have a bike with external cables and you wanted to hide them, could you drill holes in the frame and turn it into a hidden cables frame? For example would it be ok to drill through a £2000 carbon fibre frame?
Yes you could, but it depends where you drill them.

Typically you want to get them from the handlebars into the downtube. From there somehow you want one them to go through the BB into the chainstay and out the chainstay somewhere by the dropout so that you can reach the RD. The other one would go from the BB upwards towards the FD.

The best place to enter would be into the head tube. The downtube has torsional stresses on it and holes don't do well there unless they are reinforced as iin those lugs welded onto steel bike water bottle cages but not as those crimped rivets on alu frames. The latter is the worst. The former is excellent.
The head tube is pretty stable and safe to drill as long as you stay away from the bearing race seats.

On the exit point at the FD you may be able to find a reinforced bit, perhaps by the FD hanger bracket if there is one. I'll have to look at the frame to decide where I would drill it there.
As for the chainstay, anywhere near the end just before the dropout would be good. It would be thicker there.

It can be safely done but don't be a cowboy. I would suggest you find suitable grommets first and then drill to accommodate them. If can't find a suitable place but still want to go hidden Di2, then get a carbon repairer to do the job for you by making and gluing on some reinforcing lugs made from carbon sheet. You can even do this yourself, it isn't difficult. The best place to look for a carbon repairer is to go and ask at an upmarket kayak or racing scull shop or club.
 
Location
Loch side.
When hidden brake cables on the handlebars fist became popular we used to drill aluminium bars to route the cables through the bars rather than under he tape, the bars were not recessed like nowadays, I can't recall any breakages, but it must have weakened the bars, I woudn't do it to a frame, although you might do it with less worry if it is titanium.


Those bars will break. They are highly stressed and with a little stress raiser like that, will soon crack. A handlebar that breaks in a sprint is a death sentence.

Don't think titanium is any better. It has very poor fracture toughness compared to steel and not much better than aluminium. A poorly placed hole or hole with a small burr would quickly lead to a crack. Carbon fibre doesn't propagate cracks like metal does and your placement of holes is thus less critical.
 

Smokin Joe

Legendary Member
The "Drillium" era had it's heyday back in the late sixties and early seventies when every man and his uncle started to copy Eddy Merckx who began the trend. Chain rings, bars, seat posts, brake levers and even frames began turning up at races looking like oversized cheese graters, as seen here on Alf Engers bike -

Engers.jpg


The joke flying round at the time was, "Did you hear, Alf's had his knees and hips drilled this week".

Of course the top guys had the holes drilled by experts, Joe Clubman's attempts often ended in painful tears and wrecked equipment. Any weight advantage was probably more than lost by giving the machine the aerodynamics of a parachute. Still, like flared trousers it looked cool at the time.
 

screenman

Legendary Member
All of which must remain secret ...! :okay:

I suggest glueing some strong cotton onto a trained flea and get that to take it through for you. Use the cotton to pull something stronger through, and use that to pull the cable through.

If I had to improvise my own method, I would tie the cotton onto a small wad of cottonwool and use a vacuum cleaner to suck that through to the other hole. Pull the cottonwool through with tweezers if the vaccuum cleaner couldn't do it. It might be fiddly, but I reckon that I could get that to work.

I still wouldn't want to be drilling holes in my frame though!

Apologies, I run out of time. Double up a cable tie and push it through the receiving hole and this will open up inside the tube, a thin piece of wire from the other end and when you feel it is there pull the cable time back out with the thin wire inside it, note thin wire. Takes a bit of practise but I have done that on may occasions with frames that did not have guide tubes in.
 

Roadrider48

Voice of the people
Location
Londonistan
Leaving aside the frame weakening issue, how would you get the cable to come through? Frames designed for it have internal tubes that serve the same purpose as cable outer.
They don't always. My Roubaix just has the inners passing through the frame until they exit at the pre-drilled holes.
It was like that from new; only noticed it when I first recabelled it(obviously).
On the other hand my TT bike does have thin plastic sheathing running through the frame. Much easier to recabel.
 

Roadrider48

Voice of the people
Location
Londonistan
You can buy an internal cabling tool/kit from Park tools. It's basically some wire with a strong magnet on the end.
It does work quite well though.
 
Location
Loch side.
The "Drillium" era had it's heyday back in the late sixties and early seventies when every man and his uncle started to copy Eddy Merckx who began the trend. Chain rings, bars, seat posts, brake levers and even frames began turning up at races looking like oversized cheese graters, as seen here on Alf Engers bike -

View attachment 124000

The joke flying round at the time was, "Did you hear, Alf's had his knees and hips drilled this week".

Of course the top guys had the holes drilled by experts, Joe Clubman's attempts often ended in painful tears and wrecked equipment. Any weight advantage was probably more than lost by giving the machine the aerodynamics of a parachute. Still, like flared trousers it looked cool at the time.
Even his shoes were drilled.
 
Slightly OT

The trick is to always keep something in the tube either the inner or the outer cable

For instance to change the able:

Fasten the ferruled end of the cable and slide off the outer
Slider the new outer over the old inner
Fasten the new outer securely and slide out the inner
Then slide the new inner into the new outer

It really does not matter whether you slide the inner over the outer, the outer over the inner, then or the outer over the inner and the inner through the outer as long as you remember to keep the inner in the outer or the outer on the inner as opposed to removing both the outer and the inner when you should have kept both the outer or the inner in place...... Simples
 

Ian H

Ancient randonneur
Any weight advantage was probably more than lost by giving the machine the aerodynamics of a parachute.

I suspect it made very little difference, but might have marginally improved aerodynamics. It's known that rougher surfaces can help airflow over complex shapes.
 

Proto

Legendary Member
Yes you can drill holes in your bike frame, but as already stated it really depends where you drill them. I converted my LOOK 586 to take Campag EPS, and to be honest, it was fairly straightforward. The top tube might be another story though, particularly at the head tube end, as I would think it's quite highly stressed in that area. As previously suggested, entry through the head tube may be your best bet, particularly if you could machine or adapt a cable stop/support for the entry point

Before I worked on my frame I sought the advice of a carbon frame specialist and he said no reinforcing necessary (for my situation at least).

You don't actually 'drill' the holes, but instead use a small burr to grind cut away the carbon until you create a small hole, making bigger until the size and shape is achieved. I used a Dremel and various sized and shaped burrs. Take you time and it's quite easy to do.

Carbide burrs:
p23207.jpg


Some photos here of my efforts: https://www.flickr.com/photos/36600211@N03/albums/72157641723994645
 
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