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Drilling holes in carbon extensions????
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Can this be done safely? Looking at some carbon extensions that don't have exit holes for cables other than at the back.
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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My first reaction is no don‘t even think about it.

My second reaction is, but that‘s not an advise but purely a thought what would I do MYSELF: If the cross section is identical over the length of the extension, and if would have to make a hole, I would drill it near the end because there the bending moment is the smallest. Of course you would have to lead your cables all along the outside of the extensions.

But as I wrote: I do not know how carbon reacts after drilling: you are going to cut carbon fibers which also weaken parts adjacent the holes.
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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Get alloy ski bends

Eric Reid
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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The answer to "can I?" and "Should I?" might not be the same. If it is a location that is not under load (like the tail that sticks out the back of the clamp) it would probably be OK, but if it is somewhere under load, drilling the hole is going to weaken it. There is also the problem of the carbon delaminating where the bit comes out.

https://www.elevatedmaterials.com/drilling-carbon-fiber/
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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I drilled oval-shaped exit holes in my carbon extensions for Di2 cables. I have not died yet. I would do it again... Extensions are relatively thick-walled and strong because they manufacturers do not know where they will be clamped. I positioned my exit holes between the clamp points, so risk of failure due to excessive stress in that area is relatively low.
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Re: Drilling holes in carbon extensions???? [ericMPro] [ In reply to ]
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I'm trying to get my hands higher. I was thinking thinking the high rise extensions like USE.
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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That’s exactly what I use

Eric Reid
AeroFit | Instagram Portfolio
Chapel Hill, NC
Aerodynamic Optimized Bike Fitting, Retul Pre-Purchase Bike Fitting, USAT Level 1 Triathlon Coaching, Nutrition
Ask me: Scody Optimized Speed Suits | CeramicSpeed Oversized Pulley Systems | HUUB Skinsuits and Wetsuits | Ventum Bicycles and Frames
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Re: Drilling holes in carbon extensions???? [ericMPro] [ In reply to ]
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20° pad wedge and 40° high rise extensions?
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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50 because I have an undermount system

Eric Reid
AeroFit | Instagram Portfolio
Chapel Hill, NC
Aerodynamic Optimized Bike Fitting, Retul Pre-Purchase Bike Fitting, USAT Level 1 Triathlon Coaching, Nutrition
Ask me: Scody Optimized Speed Suits | CeramicSpeed Oversized Pulley Systems | HUUB Skinsuits and Wetsuits | Ventum Bicycles and Frames
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Re: Drilling holes in carbon extensions???? [ericMPro] [ In reply to ]
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ericMPro wrote:
50 because I have an undermount system

Do u feel like the bike handles sketchy with your hands that High?
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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No

Eric Reid
AeroFit | Instagram Portfolio
Chapel Hill, NC
Aerodynamic Optimized Bike Fitting, Retul Pre-Purchase Bike Fitting, USAT Level 1 Triathlon Coaching, Nutrition
Ask me: Scody Optimized Speed Suits | CeramicSpeed Oversized Pulley Systems | HUUB Skinsuits and Wetsuits | Ventum Bicycles and Frames
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Re: Drilling holes in carbon extensions???? [exxxviii] [ In reply to ]
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exxxviii wrote:
I drilled oval-shaped exit holes in my carbon extensions for Di2 cables. I have not died yet. I would do it again... Extensions are relatively thick-walled and strong because they manufacturers do not know where they will be clamped.
I positioned my exit holes between the clamp points, so risk of failure due to excessive stress in that area is relatively low.


The hole is in an area of almost zero stress, so the only real issue would be crack propagation from poor drilling. The same hole just forward of the clamp would likely be a disaster (highest stress point).

I'd say you are fairly safe if the exit holes are significantly behind the basebar clamp (no moment arm and far enough back from the clamping stresses that could cause cracking), and up next to the shifter (also a low stress area). A lot can go wrong drilling composites (esp w/o subsequent reinforcement), that's why most hole are moulded in.

Check out the video at 2:15
https://www.cyclingweekly.com/videos/watch/watch-ag2r-development-rider-crashes-high-speed-as-time-trial-bars-snap-after-going-over-bump


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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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Fishbum wrote:
Can this be done safely? Looking at some carbon extensions that don't have exit holes for cables other than at the back.

Hey Fish,

Be careful...I cant speak to every extension but we did go through multiple iterations in the SHIV development to implement the windows you see on the new carbon extensions. The hole and resulting stress concentration is 1 thing, but the broken fibers from the drill are another. Molded holes and drilled holes behave much differently. An extension that is not reinforced at the hole can have problems.


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Re: Drilling holes in carbon extensions???? [Titanflexr] [ In reply to ]
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This clip has nothing to do with drilled extensions.
It is documented that this crash happened because the contracted mechanic installed too short of bolts through the aerobar risers.

Alex Arman

Strava
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Re: Drilling holes in carbon extensions???? [Fishbum] [ In reply to ]
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Fishbum wrote:
Can this be done safely? Looking at some carbon extensions that don't have exit holes for cables other than at the back.
I drilled the S-bends for my second gen Speed Concept. I have eTap and wanted a hole where the blip mounted... drilled two clean holes and no issues. At that end of my extensions I don't really foresee any issues.

I'd be more heistant if it were a mounting point/clamp area.
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