Asked my friend and LBS owner to drill out the downtube shifter mount on this Surly Disc Trucker frame, but I was pretty surprised when I came to pick it up. Many of us have considered how to utilize these bosses, and my idea was to route a dropper.
He was considering how the angle of the cable (and housing…).
Looking for discussion and thoughts from folks with frame knowledge and experience on both structural integrity and options for finishing this. I know there are frames with similar sized holes in similar locations – even e-bikes of poorer quality tubing, drilled for internal cable routing and keys. Thanks!
by Bike4Burritos
20 Comments
I’m no engineer, but i would be concerned about this affecting the frame’s structural integrity.
Big hole you got there
Im studying engineering, looks like a pretty big hole like.
Your friend and LBS owner shouldn’t be allowed to use a drill. Even IFF the structural integrity is still good – the hole is massively oversized.
Wanna drill a hole that’s able to route a cable at an angle? Then drill the hole in that fucking angle. What the fuck was he thinking?
Far too big, unreinforced…. and pointless. If you needed an internally routed dropper on your touring bike there’s no point routing the cable through the downtube
It does look well deburred at least
Personally I’d get a cable a grommet and run my cable and send it. If you’re really concerned take it to a welder and have them patch it up. I’ve taken a few older trek MTB frames and have drilled my own holes for internal routing with no issues. Ridden heavily on trails. Overall I think you’re going to be okay.
Congrats, you ruined a perfectly good frame for something you should have asked this sub before doing anything that – and I am sorry to say – stupid.
I’m not an engineer, but Surly’s are pretty freaking strong and this is in the middle of the tube, not near any joints or bends.
Unless you’re like 400 pounds I’d build it up and ride it
I don’t think it’s a problem. Close to the neutral axis for what is likely the driving load case [bending]
I am a ti fabricator. How we do internal routing is to use a 3/8 end mill and drill into tube at a 60 degree angle then weld in a piece of 3/8 tubing. This one is 1/2″ For running multiple lines. Any steel fab guy could do it for you. Steel is easy.
https://preview.redd.it/ems6imwj1ave1.jpeg?width=3024&format=pjpg&auto=webp&s=83afb7d1f7261778792b845bce474af7ed705860
I would not let the curbs that are driven over be too high at high speed
Dont ride this. Do you really want to see what “if” means?
That’s a hole that’s been wholly holed if ever i saw/drilled one
Chromoly 4130 has a tensile strength of 97,300psi. You will be fine.
>He was considering how the angle of the cable
How many hours did he leave, between ripping the huge bong, and deciding this was the best approach to the job?
I’ve repaired these with internal housing covers. You’ll need to have someone hit it with a wire wheel and silver solder (or braze) it in place then restore the paint as needed. Silver solder is lower temp so you might be able to spare the decals. The other choice is to gusset it with a scrap piece of tubing cut to cover the hole.
[Internal housing cover – 2 & 10-packs – Framebuilder Supply](https://framebuildersupply.com/collections/housting-cable-guides/products/internal-housing-cover-2-10-packs)
Yet another “I’m an engineer”, but I’m an engineer and I would be pissed off if this was my frame! Bring it to a frame builder and have them patch it back together. Good luck OP.
A hole like that should have a reinforcement brazed on it. I had a similar but smaller hole in a top tube to route a brake cable and cracks were radiating from it after a few years. It’s a stress concentrator.
Insert obligatory “That’s what she said” joke here…
For anyone saying this hole “diminished the structural integrity of the frame” please watch Sam Pilgrims video he did I think last week where he drilled about 100 holes to mount smaller wheels in an aluminum (which is much more brittle then steel) rim and it was completely fine. If that aluminum rim can stand up to the abuse he put it through I’m pretty this steel frame will be fine with that maybe 3/8 inch hole. This is a touring bike after all. I don’t think OP is going to take it off any sick jumps. Even if he installs shocks and pegs.