Drilling the clamping area of carbon handlebar for internal cable routing

[dorin]

I’m looking in adding clip-ons for the new BMC TImemachine Road01, they’re super comfortable on long rides.i i have my eyes on the METRON 4D FLAT M.A.S as it has integrated support for clip on.

NOW in order to keep all neat I’d like to keep the integrated cable option.

One alternative would be to get the ICS Stem, instead of the aero one but the braking cables will be visible near the stem area.

I googled and I find mixed opinions, some even here on weightweenies, but does anyone has any experience with drilling a hole at the clamping area (diameter 1cm) that would allow the internal routing into the stem? Or drilling two 5mm holes could also be an option.

The metron 4d is strong enough allowing for clip on, the drill will not have corners (important for structural resistance), in theory should be fine but the idea freaks me out, anyone with experience on this or is it a hands down a dumb way to go?

Cheers,
Dorin

[davidalone]

This would be a stupid idea.

You're drilling into one of the most highly stressed areas on a bike, one, that if fails, can cause injury and death.

Drilling holes introduces what is called a 'stress riser' in engineeeing parlance into the system.
Google it to see what happens when you have a stress riser. Without designing for it, there is no telling how you would influence the fatigue life of the bar. You would also very likely lower the compressive strength of the area, 1cm is a huge hole w.r.t. the overall size of the bar.

If you did do it, you'd also need to do it properly with a special drill bit for drilling CF. Do it incorrectly and you risk delamination of the area.

Too mamy things can go wrong for the sake of vanity.

[alcatraz]

I have chinese bars that come predrilled close to the clamp area for the cables. I see that they have now updated the design, probably because of fractures around the drill points.

What they did was to drill the cable entry holes on the underside of the bars on flat section near the round tube. The exit holes are just 10cm away almost by the stem clamp area.

The bartape covers the cables anyway so it makes no differerence if they enter the bars on the corner/flat section or directly into the round tube.

[dorin]

Too mamy things can go wrong for the sake of vanity.

agree...

[Butcher]

Yes, I have done it. 3 times. Never had a problem. 5-10 thousand miles on the part too.

The hole I drilled was large enough to shove the SR11 EPS connectors thru. The interface fits inside the stem. I even drilled holes in the steering tube so the cable can continue into the frame . I used a FSA handle bar and yes, it is very thick in that area.

Remember, there are people that say you can't and will prove it to you without ever doing it. Then there are butchers on the internet that will try most anything. I do not know if you could go to 10mm, but mine is just large enough to get the EPS connector to go thru [about 6mm]. I also touched up the edges of the drilled hole with epoxy.

Not certain why the font changed or how to change it so it's the same, maybe it's just on my end.

[dorin]

I did ask the manufacturer but being based in the US I doubt I’ll get any green light from them given their legal environment...glad to know you did it and was fine, I agree is stupid vanity....but on same vanity who really need a 12k bike, yet they are being sold...

[stevec1975]

Get the new Cervelo AB09 Bars (which have internal routing all the way into the stem (i.e past the clamp area) and are suitable for tri bars - Handily I have a new set for sale in the for sale section!

[C36]

100% don’t ever do it end of story.

Yes, I have done it. 3 times. Never had a problem. 5-10 thousand miles on the part too.

Saying this is criminal. You can’t give the feeling that it’s safe to do it when It is absolutely not. having no failures prove nothing.

Remember, there are people that say you can't and will prove it to you without ever doing it. Then there are butchers on the internet that will try most anything. I do not know if you could go to 10mm, but mine is just large enough to get the EPS connector to go thru [about 6mm]. I also touched up the edges of the drilled hole with epoxy.

As mentioned above that’s 101 mechanical engineering. Drilling a hole cause stress concentration. Very ball park, the diameter of your hole / bar diameter ratio is 0.2 that imply that stress is 3 times higher around the hole when the bar sees flexion. While the stem absorb a big part of it, you have zero warranty that you will remain within the mech limit of the material under a shock.

Finally if we talk about a composite bar, a random drilling is likely to cause micro delamination then more stress concentration...

Yes I am getting a bit upset but can’t let people doing dangerous things on a cockpit...



Envoyé de mon iPhone en utilisant Tapatalk

[Butcher]

The OP asked if anyone has done it. I mentioned that I have and have had no issues. Again, many people say you can't and will prove it on paper. I can say I have and proved it by doing it.

The world was once flat one day until someone sailed and found it was not.

Boeing engineers said their stall software will work and it was found out that, maybe, it does not [by real people].

I get what you are saying, but sometimes real life trumps engineers. I believe the OP has big boy pants and can make his own decision.

[wheelsONfire]

Just go as far and ask yourself, what if the bar would crack when you're descending in high speed.

[none]

AFAIK, drilling holes into any parts is "at your own risk".
It's doable, but never safe.
Just because someone else had done it without failure or unintended consequences, doesn't meant the same would apply to anyone else.

[kode54]

There's holes for brake housing...eTube wires fit nicely along side the same holes. Use the existing holes for all internal cable wiring.

[mattr]

I mentioned that I have and have had no issues.

Yet, it's most likely that fatigue life will be impacted.

Again, many people say you can't and will prove it on paper. I can say I have and proved it by doing it.

Two things, 1) you haven't proven anything. 2) where do you think the knowledge to do the exercise "on paper" actually comes from? A few equations someone knocked up in an afternoon. Or thousands of test pieces over many years to work out exactly what the equations (and rules of thumb) should actually be?

I mean, referencing another thread, but how do you thing they work out how to do the balancing and how well balanced things need to be in the auto industry?

[AJS914]

Back to the OP, yes it's a dumb way to go. The risk is too great.

[dorin]

Many thanks for all the replies! I was expecting is a dumb idea, you know sometimes you want to hear the other voices spelling out your inner doubts. Also the manufacturer confirmed is a stupid idea and no, they don’t even offer to drill it for you. Given I enjoy alpine passes, with the subsequent alpine descent (fastest speed ever was 97.4km/hr) I can’t take dumb risks, as someone here said, is too much of a price to pay for vanity, i’ll Have to live with cables being visible, maybe someone will release a nice flat aerobars with full internal routing, till then I’ll chose life