I’m trying to figure out the cable routing for my current frame project. It has a 68mm BB, under-BB cable routing, and I’m trying to clear the 3rd underside DT bottle cage, a kickstand plate (per customer request), S-bend chainstays, and 2.35mm tires.
I’ve resorted to fabbing my own plastic guide, but I’m not happy with how it looks so far.
Has anyone tackled this in a better way?
Thanks!
-Jim G
If you can find the right tubing, using a small diameter steel that’s brazed into place can be nice because you can introduce slight bends into the guide.
Those guides as shown above are available from Ceeway in UK. Otherwise, as for finding the right tubing, could you just use car brake pipe? It’s basically the same size. But maybe tricky to braze on. There are “steel” brake pipes around but they might be some unusual alloy.
Do you need to run exposed cables?
Automotive brake line is just mild steel, there is a nickel/copper flavor that bends and flares easier than the steel, might be worth looking at, not sure if it can be brazed
Take two derailleur cable with you to the local hardware store. Purchase a minimal steel or stainless tube that both cables fit thru. Then file a groove in your bottom bracket shell that follows the path where you want your cables. Then, WITH THE TWO DERAILLEUR CABLES, still in the tube, bend the tubing to your desired radius. Remove the cables, cut the tube to your desired dimension. Braze the tubes into place. File as you like. As soon as I figure out how to upload a photo (I’m old) I will post a MAX BB I did several years ago.[quote=“Jess, post:6, topic:4572, full:true”]
Take two derailleur cable with you to the local hardware store. Purchase a minimal steel or stainless tube that both cables fit thru. Then file a groove in your bottom bracket shell that follows the path where you want your cables. Then, WITH THE TWO DERAILLEUR CABLES, still in the tube, bend the tubing to your desired radius. Remove the cables, cut the tube to your desired dimension. Braze the tubes into place. File as you like.
I also use brazed on tubing. I’ve been using this tubing: McMaster-Carr
It’s stainless, which is nice, because this is a wear spot, and pretty exposed. I’ve been considering trying this with brass tubing too, but it’ll be a while because I still have probably two feet of this stainless stuff, and I only use a couple inches at a time.
I also bought this bender ages ago: McMaster-Carr. It’s been great for small tubing like this, but it doesn’t bend it quite tight enough, so I have to manually form it around the BB.
I use Harris 50N for this. It’s tricky soldering, because those little bits of 1/8" tubing want to heat up super fast, but the BB takes forever to get up to temp.
This is what it looks like when I do it:
I also use a bit of liner from jagwire sealed cables to make the cables move really smoothly through these little noodles. (Those cables are really fantastic, so you might consider using them for the build. And whenever I use them, I keep the extra bits of liner so I can use them in a BB guide like this.)
I don’t have a great picture of that, but here’s a bad picture of it. (zoomed in from a wider shot of the whole bike). You can see the little bit of white cable liner sticking out of the guide.
Oh! And holding these little noodles in place while you’re torching can be a pain. I pass a stout steel wire through the noodle, then pull it tight around the other side of the bottom bracket. This works fine, I guess. There are probable better ways.
Since you need to snake the cable around all those things, you can use the old school way of using cable stops and housing just round the BB.
